Merge tag 'for-linus-6.16-1' of https://github.com/cminyard/linux-ipmi

Pull IPMI updates from Corey Minyard:
 "Restructure the IPMI driver.

  This is a restructure of the IPMI driver, mostly to remove SRCU. The
  locking had issues, and they were not going to be straightforward to
  fix. Plus it used tons of memory and was generally a pain.

  Most of this moves handling of messages out of bh and interrupt
  context and runs it in thread context. Then getting rid of SRCU is
  easy.

  This also has a minor cleanup to remove a warning on newer GCCs and to
  fix some documentation"

* tag 'for-linus-6.16-1' of https://github.com/cminyard/linux-ipmi: (26 commits)
  docs: ipmi: fix spelling and grammar mistakes
  ipmi:msghandler: Fix potential memory corruption in ipmi_create_user()
  ipmi:watchdog: Use the new interface for panic messages
  ipmi:msghandler: Export and fix panic messaging capability
  Documentation:ipmi: Remove comments about interrupt level
  ipmi:ssif: Fix a shutdown race
  ipmi:msghandler: Don't deliver messages to deleted users
  ipmi:si: Rework startup of IPMI devices
  ipmi:msghandler: Add a error return from unhandle LAN cmds
  ipmi:msghandler: Shut down lower layer first at unregister
  ipmi:msghandler: Remove proc_fs.h
  ipmi:msghandler: Don't check for shutdown when returning responses
  ipmi:msghandler: Don't acquire a user refcount for queued messages
  ipmi:msghandler: Fix locking around users and interfaces
  ipmi:msghandler: Remove some user level processing in panic mode
  ipmi: Add a note about the pretimeout callback
  ipmi:watchdog: Change lock to mutex
  ipmi:msghandler: Remove srcu for the ipmi_interfaces list
  ipmi:msghandler: Remove srcu from the ipmi user structure
  ipmi:msghandler: Use the system_wq, not system_bh_wq
  ...

10 files changed, 584 insertions, 524 deletions

diff --git a/Documentation/driver-api/ipmi.rst b/Documentation/driver-api/ipmi.rst
index dfa021eacd63..2cc6c898ab90 100644
--- a/Documentation/driver-api/ipmi.rst
+++ b/Documentation/driver-api/ipmi.rst
@@ -45,7 +45,7 @@ manual), choose the 'IPMI SI handler' option.  A driver also exists
 for direct I2C access to the IPMI management controller.  Some boards
 support this, but it is unknown if it will work on every board.  For
 this, choose 'IPMI SMBus handler', but be ready to try to do some
-figuring to see if it will work on your system if the SMBIOS/APCI
+figuring to see if it will work on your system if the SMBIOS/ACPI
 information is wrong or not present.  It is fairly safe to have both
 these enabled and let the drivers auto-detect what is present.
 
@@ -63,7 +63,7 @@ situation, you need to read the section below named 'The SI Driver' or
 IPMI defines a standard watchdog timer.  You can enable this with the
 'IPMI Watchdog Timer' config option.  If you compile the driver into
 the kernel, then via a kernel command-line option you can have the
-watchdog timer start as soon as it initializes.  It also have a lot
+watchdog timer start as soon as it initializes.  It also has a lot
 of other options, see the 'Watchdog' section below for more details.
 Note that you can also have the watchdog continue to run if it is
 closed (by default it is disabled on close).  Go into the 'Watchdog
@@ -280,10 +280,8 @@ Creating the User
 To use the message handler, you must first create a user using
 ipmi_create_user.  The interface number specifies which SMI you want
 to connect to, and you must supply callback functions to be called
-when data comes in.  The callback function can run at interrupt level,
-so be careful using the callbacks.  This also allows to you pass in a
-piece of data, the handler_data, that will be passed back to you on
-all calls.
+when data comes in.  This also allows to you pass in a piece of data,
+the handler_data, that will be passed back to you on all calls.
 
 Once you are done, call ipmi_destroy_user() to get rid of the user.
 
@@ -303,8 +301,7 @@ use it for anything you like.
 
 Responses come back in the function pointed to by the ipmi_recv_hndl
 field of the "handler" that you passed in to ipmi_create_user().
-Remember again, these may be running at interrupt level.  Remember to
-look at the receive type, too.
+Remember to look at the receive type, too.
 
 From userland, you fill out an ipmi_req_t structure and use the
 IPMICTL_SEND_COMMAND ioctl.  For incoming stuff, you can use select()
@@ -317,13 +314,13 @@ This gives the receiver a place to actually put the message.
 
 If the message cannot fit into the data you provide, you will get an
 EMSGSIZE error and the driver will leave the data in the receive
-queue.  If you want to get it and have it truncate the message, us
+queue.  If you want to get it and have it truncate the message, use
 the IPMICTL_RECEIVE_MSG_TRUNC ioctl.
 
 When you send a command (which is defined by the lowest-order bit of
 the netfn per the IPMI spec) on the IPMB bus, the driver will
 automatically assign the sequence number to the command and save the
-command.  If the response is not receive in the IPMI-specified 5
+command.  If the response is not received in the IPMI-specified 5
 seconds, it will generate a response automatically saying the command
 timed out.  If an unsolicited response comes in (if it was after 5
 seconds, for instance), that response will be ignored.
@@ -367,7 +364,7 @@ channel bitmasks do not overlap.
 
 To respond to a received command, set the response bit in the returned
 netfn, use the address from the received message, and use the same
-msgid that you got in the receive message.
+msgid that you got in the received message.
 
 From userland, equivalent IOCTLs are provided to do these functions.
 
@@ -440,7 +437,7 @@ register would be 0xca6.  This defaults to 1.
 
 The regsizes parameter gives the size of a register, in bytes.  The
 data used by IPMI is 8-bits wide, but it may be inside a larger
-register.  This parameter allows the read and write type to specified.
+register.  This parameter allows the read and write type to be specified.
 It may be 1, 2, 4, or 8.  The default is 1.
 
 Since the register size may be larger than 32 bits, the IPMI data may not
@@ -481,8 +478,8 @@ If your IPMI interface does not support interrupts and is a KCS or
 SMIC interface, the IPMI driver will start a kernel thread for the
 interface to help speed things up.  This is a low-priority kernel
 thread that constantly polls the IPMI driver while an IPMI operation
-is in progress.  The force_kipmid module parameter will all the user to
-force this thread on or off.  If you force it off and don't have
+is in progress.  The force_kipmid module parameter will allow the user
+to force this thread on or off.  If you force it off and don't have
 interrupts, the driver will run VERY slowly.  Don't blame me,
 these interfaces suck.
 
@@ -583,7 +580,7 @@ kernel command line as::
 These are the same options as on the module command line.
 
 The I2C driver does not support non-blocking access or polling, so
-this driver cannod to IPMI panic events, extend the watchdog at panic
+this driver cannot do IPMI panic events, extend the watchdog at panic
 time, or other panic-related IPMI functions without special kernel
 patches and driver modifications.  You can get those at the openipmi
 web page.
@@ -610,7 +607,7 @@ Parameters are::
 	ipmi_ipmb.retry_time_ms=<Time between retries on IPMB>
 	ipmi_ipmb.max_retries=<Number of times to retry a message>
 
-Loading the module will not result in the driver automatcially
+Loading the module will not result in the driver automatically
 starting unless there is device tree information setting it up.  If
 you want to instantiate one of these by hand, do::
 
diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 3ba9d7e9a6c7..064944ae9fdc 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -27,7 +27,6 @@
 #include <linux/ipmi_smi.h>
 #include <linux/notifier.h>
 #include <linux/init.h>
-#include <linux/proc_fs.h>
 #include <linux/rcupdate.h>
 #include <linux/interrupt.h>
 #include <linux/moduleparam.h>
@@ -41,11 +40,12 @@
 
 static struct ipmi_recv_msg *ipmi_alloc_recv_msg(void);
 static int ipmi_init_msghandler(void);
-static void smi_recv_work(struct work_struct *t);
+static void smi_work(struct work_struct *t);
 static void handle_new_recv_msgs(struct ipmi_smi *intf);
 static void need_waiter(struct ipmi_smi *intf);
 static int handle_one_recv_msg(struct ipmi_smi *intf,
 			       struct ipmi_smi_msg *msg);
+static void intf_free(struct kref *ref);
 
 static bool initialized;
 static bool drvregistered;
@@ -180,14 +180,8 @@ MODULE_PARM_DESC(max_msgs_per_user,
 struct ipmi_user {
 	struct list_head link;
 
-	/*
-	 * Set to NULL when the user is destroyed, a pointer to myself
-	 * so srcu_dereference can be used on it.
-	 */
-	struct ipmi_user *self;
-	struct srcu_struct release_barrier;
-
 	struct kref refcount;
+	refcount_t destroyed;
 
 	/* The upper layer that handles receive messages. */
 	const struct ipmi_user_hndl *handler;
@@ -200,30 +194,8 @@ struct ipmi_user {
 	bool gets_events;
 
 	atomic_t nr_msgs;
-
-	/* Free must run in process context for RCU cleanup. */
-	struct work_struct remove_work;
 };
 
-static struct workqueue_struct *remove_work_wq;
-
-static struct ipmi_user *acquire_ipmi_user(struct ipmi_user *user, int *index)
-	__acquires(user->release_barrier)
-{
-	struct ipmi_user *ruser;
-
-	*index = srcu_read_lock(&user->release_barrier);
-	ruser = srcu_dereference(user->self, &user->release_barrier);
-	if (!ruser)
-		srcu_read_unlock(&user->release_barrier, *index);
-	return ruser;
-}
-
-static void release_ipmi_user(struct ipmi_user *user, int index)
-{
-	srcu_read_unlock(&user->release_barrier, index);
-}
-
 struct cmd_rcvr {
 	struct list_head link;
 
@@ -327,6 +299,8 @@ struct bmc_device {
 };
 #define to_bmc_device(x) container_of((x), struct bmc_device, pdev.dev)
 
+static struct workqueue_struct *bmc_remove_work_wq;
+
 static int bmc_get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc,
 			     struct ipmi_device_id *id,
 			     bool *guid_set, guid_t *guid);
@@ -451,11 +425,10 @@ struct ipmi_smi {
 	struct list_head link;
 
 	/*
-	 * The list of upper layers that are using me.  seq_lock write
-	 * protects this.  Read protection is with srcu.
+	 * The list of upper layers that are using me.
 	 */
 	struct list_head users;
-	struct srcu_struct users_srcu;
+	struct mutex users_mutex;
 	atomic_t nr_users;
 	struct device_attribute nr_users_devattr;
 	struct device_attribute nr_msgs_devattr;
@@ -496,15 +469,22 @@ struct ipmi_smi {
 	int curr_seq;
 
 	/*
-	 * Messages queued for delivery.  If delivery fails (out of memory
-	 * for instance), They will stay in here to be processed later in a
-	 * periodic timer interrupt.  The workqueue is for handling received
-	 * messages directly from the handler.
+	 * Messages queued for deliver to the user.
+	 */
+	struct mutex user_msgs_mutex;
+	struct list_head user_msgs;
+
+	/*
+	 * Messages queued for processing.  If processing fails (out
+	 * of memory for instance), They will stay in here to be
+	 * processed later in a periodic timer interrupt.  The
+	 * workqueue is for handling received messages directly from
+	 * the handler.
 	 */
 	spinlock_t       waiting_rcv_msgs_lock;
 	struct list_head waiting_rcv_msgs;
 	atomic_t	 watchdog_pretimeouts_to_deliver;
-	struct work_struct recv_work;
+	struct work_struct smi_work;
 
 	spinlock_t             xmit_msgs_lock;
 	struct list_head       xmit_msgs;
@@ -522,10 +502,9 @@ struct ipmi_smi {
 	 * Events that were queues because no one was there to receive
 	 * them.
 	 */
-	spinlock_t       events_lock; /* For dealing with event stuff. */
+	struct mutex     events_mutex; /* For dealing with event stuff. */
 	struct list_head waiting_events;
 	unsigned int     waiting_events_count; /* How many events in queue? */
-	char             delivering_events;
 	char             event_msg_printed;
 
 	/* How many users are waiting for events? */
@@ -613,6 +592,28 @@ static int __ipmi_bmc_register(struct ipmi_smi *intf,
 			       bool guid_set, guid_t *guid, int intf_num);
 static int __scan_channels(struct ipmi_smi *intf, struct ipmi_device_id *id);
 
+static void free_ipmi_user(struct kref *ref)
+{
+	struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount);
+	struct module *owner;
+
+	owner = user->intf->owner;
+	kref_put(&user->intf->refcount, intf_free);
+	module_put(owner);
+	vfree(user);
+}
+
+static void release_ipmi_user(struct ipmi_user *user)
+{
+	kref_put(&user->refcount, free_ipmi_user);
+}
+
+static struct ipmi_user *acquire_ipmi_user(struct ipmi_user *user)
+{
+	if (!kref_get_unless_zero(&user->refcount))
+		return NULL;
+	return user;
+}
 
 /*
  * The driver model view of the IPMI messaging driver.
@@ -630,9 +631,6 @@ static DEFINE_MUTEX(ipmidriver_mutex);
 
 static LIST_HEAD(ipmi_interfaces);
 static DEFINE_MUTEX(ipmi_interfaces_mutex);
-#define ipmi_interfaces_mutex_held() \
-	lockdep_is_held(&ipmi_interfaces_mutex)
-static struct srcu_struct ipmi_interfaces_srcu;
 
 /*
  * List of watchers that want to know when smi's are added and deleted.
@@ -698,27 +696,20 @@ static void free_smi_msg_list(struct list_head *q)
 	}
 }
 
-static void clean_up_interface_data(struct ipmi_smi *intf)
+static void intf_free(struct kref *ref)
 {
+	struct ipmi_smi *intf = container_of(ref, struct ipmi_smi, refcount);
 	int              i;
 	struct cmd_rcvr  *rcvr, *rcvr2;
-	struct list_head list;
-
-	cancel_work_sync(&intf->recv_work);
 
 	free_smi_msg_list(&intf->waiting_rcv_msgs);
 	free_recv_msg_list(&intf->waiting_events);
 
 	/*
 	 * Wholesale remove all the entries from the list in the
-	 * interface and wait for RCU to know that none are in use.
+	 * interface.  No need for locks, this is single-threaded.
 	 */
-	mutex_lock(&intf->cmd_rcvrs_mutex);
-	INIT_LIST_HEAD(&list);
-	list_splice_init_rcu(&intf->cmd_rcvrs, &list, synchronize_rcu);
-	mutex_unlock(&intf->cmd_rcvrs_mutex);
-
-	list_for_each_entry_safe(rcvr, rcvr2, &list, link)
+	list_for_each_entry_safe(rcvr, rcvr2, &intf->cmd_rcvrs, link)
 		kfree(rcvr);
 
 	for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
@@ -726,20 +717,17 @@ static void clean_up_interface_data(struct ipmi_smi *intf)
 					&& (intf->seq_table[i].recv_msg))
 			ipmi_free_recv_msg(intf->seq_table[i].recv_msg);
 	}
-}
-
-static void intf_free(struct kref *ref)
-{
-	struct ipmi_smi *intf = container_of(ref, struct ipmi_smi, refcount);
 
-	clean_up_interface_data(intf);
 	kfree(intf);
 }
 
 int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
 {
 	struct ipmi_smi *intf;
-	int index, rv;
+	unsigned int count = 0, i;
+	int *interfaces = NULL;
+	struct device **devices = NULL;
+	int rv = 0;
 
 	/*
 	 * Make sure the driver is actually initialized, this handles
@@ -753,20 +741,53 @@ int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
 
 	list_add(&watcher->link, &smi_watchers);
 
-	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link,
-			lockdep_is_held(&smi_watchers_mutex)) {
-		int intf_num = READ_ONCE(intf->intf_num);
+	/*
+	 * Build an array of ipmi interfaces and fill it in, and
+	 * another array of the devices.  We can't call the callback
+	 * with ipmi_interfaces_mutex held.  smi_watchers_mutex will
+	 * keep things in order for the user.
+	 */
+	mutex_lock(&ipmi_interfaces_mutex);
+	list_for_each_entry(intf, &ipmi_interfaces, link)
+		count++;
+	if (count > 0) {
+		interfaces = kmalloc_array(count, sizeof(*interfaces),
+					   GFP_KERNEL);
+		if (!interfaces) {
+			rv = -ENOMEM;
+		} else {
+			devices = kmalloc_array(count, sizeof(*devices),
+						GFP_KERNEL);
+			if (!devices) {
+				kfree(interfaces);
+				interfaces = NULL;
+				rv = -ENOMEM;
+			}
+		}
+		count = 0;
+	}
+	if (interfaces) {
+		list_for_each_entry(intf, &ipmi_interfaces, link) {
+			int intf_num = READ_ONCE(intf->intf_num);
 
-		if (intf_num == -1)
-			continue;
-		watcher->new_smi(intf_num, intf->si_dev);
+			if (intf_num == -1)
+				continue;
+			devices[count] = intf->si_dev;
+			interfaces[count++] = intf_num;
+		}
+	}
+	mutex_unlock(&ipmi_interfaces_mutex);
+
+	if (interfaces) {
+		for (i = 0; i < count; i++)
+			watcher->new_smi(interfaces[i], devices[i]);
+		kfree(interfaces);
+		kfree(devices);
 	}
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
 
 	mutex_unlock(&smi_watchers_mutex);
 
-	return 0;
+	return rv;
 }
 EXPORT_SYMBOL(ipmi_smi_watcher_register);
 
@@ -779,22 +800,17 @@ int ipmi_smi_watcher_unregister(struct ipmi_smi_watcher *watcher)
 }
 EXPORT_SYMBOL(ipmi_smi_watcher_unregister);
 
-/*
- * Must be called with smi_watchers_mutex held.
- */
 static void
 call_smi_watchers(int i, struct device *dev)
 {
 	struct ipmi_smi_watcher *w;
 
-	mutex_lock(&smi_watchers_mutex);
 	list_for_each_entry(w, &smi_watchers, link) {
 		if (try_module_get(w->owner)) {
 			w->new_smi(i, dev);
 			module_put(w->owner);
 		}
 	}
-	mutex_unlock(&smi_watchers_mutex);
 }
 
 static int
@@ -941,18 +957,14 @@ static int deliver_response(struct ipmi_smi *intf, struct ipmi_recv_msg *msg)
 		ipmi_free_recv_msg(msg);
 		atomic_dec(&msg->user->nr_msgs);
 	} else {
-		int index;
-		struct ipmi_user *user = acquire_ipmi_user(msg->user, &index);
-
-		if (user) {
-			atomic_dec(&user->nr_msgs);
-			user->handler->ipmi_recv_hndl(msg, user->handler_data);
-			release_ipmi_user(user, index);
-		} else {
-			/* User went away, give up. */
-			ipmi_free_recv_msg(msg);
-			rv = -EINVAL;
-		}
+		/*
+		 * Deliver it in smi_work.  The message will hold a
+		 * refcount to the user.
+		 */
+		mutex_lock(&intf->user_msgs_mutex);
+		list_add_tail(&msg->link, &intf->user_msgs);
+		mutex_unlock(&intf->user_msgs_mutex);
+		queue_work(system_wq, &intf->smi_work);
 	}
 
 	return rv;
@@ -1192,23 +1204,14 @@ static int intf_err_seq(struct ipmi_smi *intf,
 	return rv;
 }
 
-static void free_user_work(struct work_struct *work)
-{
-	struct ipmi_user *user = container_of(work, struct ipmi_user,
-					      remove_work);
-
-	cleanup_srcu_struct(&user->release_barrier);
-	vfree(user);
-}
-
 int ipmi_create_user(unsigned int          if_num,
 		     const struct ipmi_user_hndl *handler,
 		     void                  *handler_data,
 		     struct ipmi_user      **user)
 {
 	unsigned long flags;
-	struct ipmi_user *new_user;
-	int           rv, index;
+	struct ipmi_user *new_user = NULL;
+	int           rv = 0;
 	struct ipmi_smi *intf;
 
 	/*
@@ -1230,30 +1233,31 @@ int ipmi_create_user(unsigned int          if_num,
 	if (rv)
 		return rv;
 
-	new_user = vzalloc(sizeof(*new_user));
-	if (!new_user)
-		return -ENOMEM;
-
-	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+	mutex_lock(&ipmi_interfaces_mutex);
+	list_for_each_entry(intf, &ipmi_interfaces, link) {
 		if (intf->intf_num == if_num)
 			goto found;
 	}
 	/* Not found, return an error */
 	rv = -EINVAL;
-	goto out_kfree;
+	goto out_unlock;
 
  found:
+	if (intf->in_shutdown) {
+		rv = -ENODEV;
+		goto out_unlock;
+	}
+
 	if (atomic_add_return(1, &intf->nr_users) > max_users) {
 		rv = -EBUSY;
 		goto out_kfree;
 	}
 
-	INIT_WORK(&new_user->remove_work, free_user_work);
-
-	rv = init_srcu_struct(&new_user->release_barrier);
-	if (rv)
+	new_user = vzalloc(sizeof(*new_user));
+	if (!new_user) {
+		rv = -ENOMEM;
 		goto out_kfree;
+	}
 
 	if (!try_module_get(intf->owner)) {
 		rv = -ENODEV;
@@ -1265,64 +1269,58 @@ int ipmi_create_user(unsigned int          if_num,
 
 	atomic_set(&new_user->nr_msgs, 0);
 	kref_init(&new_user->refcount);
+	refcount_set(&new_user->destroyed, 1);
+	kref_get(&new_user->refcount); /* Destroy owns a refcount. */
 	new_user->handler = handler;
 	new_user->handler_data = handler_data;
 	new_user->intf = intf;
 	new_user->gets_events = false;
 
-	rcu_assign_pointer(new_user->self, new_user);
+	mutex_lock(&intf->users_mutex);
 	spin_lock_irqsave(&intf->seq_lock, flags);
-	list_add_rcu(&new_user->link, &intf->users);
+	list_add(&new_user->link, &intf->users);
 	spin_unlock_irqrestore(&intf->seq_lock, flags);
+	mutex_unlock(&intf->users_mutex);
+
 	if (handler->ipmi_watchdog_pretimeout)
 		/* User wants pretimeouts, so make sure to watch for them. */
 		smi_add_watch(intf, IPMI_WATCH_MASK_CHECK_WATCHDOG);
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
-	*user = new_user;
-	return 0;
 
 out_kfree:
-	atomic_dec(&intf->nr_users);
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
-	vfree(new_user);
+	if (rv) {
+		atomic_dec(&intf->nr_users);
+		vfree(new_user);
+	} else {
+		*user = new_user;
+	}
+out_unlock:
+	mutex_unlock(&ipmi_interfaces_mutex);
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_create_user);
 
 int ipmi_get_smi_info(int if_num, struct ipmi_smi_info *data)
 {
-	int rv, index;
+	int rv = -EINVAL;
 	struct ipmi_smi *intf;
 
-	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
-		if (intf->intf_num == if_num)
-			goto found;
+	mutex_lock(&ipmi_interfaces_mutex);
+	list_for_each_entry(intf, &ipmi_interfaces, link) {
+		if (intf->intf_num == if_num) {
+			if (!intf->handlers->get_smi_info)
+				rv = -ENOTTY;
+			else
+				rv = intf->handlers->get_smi_info(intf->send_info, data);
+			break;
+		}
 	}
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
-
-	/* Not found, return an error */
-	return -EINVAL;
-
-found:
-	if (!intf->handlers->get_smi_info)
-		rv = -ENOTTY;
-	else
-		rv = intf->handlers->get_smi_info(intf->send_info, data);
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
+	mutex_unlock(&ipmi_interfaces_mutex);
 
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_get_smi_info);
 
-static void free_user(struct kref *ref)
-{
-	struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount);
-
-	/* SRCU cleanup must happen in workqueue context. */
-	queue_work(remove_work_wq, &user->remove_work);
-}
-
+/* Must be called with intf->users_mutex held. */
 static void _ipmi_destroy_user(struct ipmi_user *user)
 {
 	struct ipmi_smi  *intf = user->intf;
@@ -1330,21 +1328,10 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 	unsigned long    flags;
 	struct cmd_rcvr  *rcvr;
 	struct cmd_rcvr  *rcvrs = NULL;
-	struct module    *owner;
+	struct ipmi_recv_msg *msg, *msg2;
 
-	if (!acquire_ipmi_user(user, &i)) {
-		/*
-		 * The user has already been cleaned up, just make sure
-		 * nothing is using it and return.
-		 */
-		synchronize_srcu(&user->release_barrier);
+	if (!refcount_dec_if_one(&user->destroyed))
 		return;
-	}
-
-	rcu_assign_pointer(user->self, NULL);
-	release_ipmi_user(user, i);
-
-	synchronize_srcu(&user->release_barrier);
 
 	if (user->handler->shutdown)
 		user->handler->shutdown(user->handler_data);
@@ -1355,11 +1342,11 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 	if (user->gets_events)
 		atomic_dec(&intf->event_waiters);
 
-	/* Remove the user from the interface's sequence table. */
-	spin_lock_irqsave(&intf->seq_lock, flags);
-	list_del_rcu(&user->link);
+	/* Remove the user from the interface's list and sequence table. */
+	list_del(&user->link);
 	atomic_dec(&intf->nr_users);
 
+	spin_lock_irqsave(&intf->seq_lock, flags);
 	for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
 		if (intf->seq_table[i].inuse
 		    && (intf->seq_table[i].recv_msg->user == user)) {
@@ -1374,7 +1361,7 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 	 * Remove the user from the command receiver's table.  First
 	 * we build a list of everything (not using the standard link,
 	 * since other things may be using it till we do
-	 * synchronize_srcu()) then free everything in that list.
+	 * synchronize_rcu()) then free everything in that list.
 	 */
 	mutex_lock(&intf->cmd_rcvrs_mutex);
 	list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
@@ -1386,23 +1373,33 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
 		}
 	}
 	mutex_unlock(&intf->cmd_rcvrs_mutex);
-	synchronize_rcu();
 	while (rcvrs) {
 		rcvr = rcvrs;
 		rcvrs = rcvr->next;
 		kfree(rcvr);
 	}
 
-	owner = intf->owner;
-	kref_put(&intf->refcount, intf_free);
-	module_put(owner);
+	mutex_lock(&intf->user_msgs_mutex);
+	list_for_each_entry_safe(msg, msg2, &intf->user_msgs, link) {
+		if (msg->user != user)
+			continue;
+		list_del(&msg->link);
+		ipmi_free_recv_msg(msg);
+	}
+	mutex_unlock(&intf->user_msgs_mutex);
+
+	release_ipmi_user(user);
 }
 
 void ipmi_destroy_user(struct ipmi_user *user)
 {
+	struct ipmi_smi *intf = user->intf;
+
+	mutex_lock(&intf->users_mutex);
 	_ipmi_destroy_user(user);
+	mutex_unlock(&intf->users_mutex);
 
-	kref_put(&user->refcount, free_user);
+	kref_put(&user->refcount, free_ipmi_user);
 }
 EXPORT_SYMBOL(ipmi_destroy_user);
 
@@ -1411,9 +1408,9 @@ int ipmi_get_version(struct ipmi_user *user,
 		     unsigned char *minor)
 {
 	struct ipmi_device_id id;
-	int rv, index;
+	int rv;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1422,7 +1419,7 @@ int ipmi_get_version(struct ipmi_user *user,
 		*major = ipmi_version_major(&id);
 		*minor = ipmi_version_minor(&id);
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1432,9 +1429,9 @@ int ipmi_set_my_address(struct ipmi_user *user,
 			unsigned int  channel,
 			unsigned char address)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1444,7 +1441,7 @@ int ipmi_set_my_address(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		user->intf->addrinfo[channel].address = address;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1454,9 +1451,9 @@ int ipmi_get_my_address(struct ipmi_user *user,
 			unsigned int  channel,
 			unsigned char *address)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1466,7 +1463,7 @@ int ipmi_get_my_address(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		*address = user->intf->addrinfo[channel].address;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1476,9 +1473,9 @@ int ipmi_set_my_LUN(struct ipmi_user *user,
 		    unsigned int  channel,
 		    unsigned char LUN)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1488,7 +1485,7 @@ int ipmi_set_my_LUN(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		user->intf->addrinfo[channel].lun = LUN & 0x3;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1498,9 +1495,9 @@ int ipmi_get_my_LUN(struct ipmi_user *user,
 		    unsigned int  channel,
 		    unsigned char *address)
 {
-	int index, rv = 0;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1510,7 +1507,7 @@ int ipmi_get_my_LUN(struct ipmi_user *user,
 		channel = array_index_nospec(channel, IPMI_MAX_CHANNELS);
 		*address = user->intf->addrinfo[channel].lun;
 	}
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1518,17 +1515,17 @@ EXPORT_SYMBOL(ipmi_get_my_LUN);
 
 int ipmi_get_maintenance_mode(struct ipmi_user *user)
 {
-	int mode, index;
+	int mode;
 	unsigned long flags;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
 	spin_lock_irqsave(&user->intf->maintenance_mode_lock, flags);
 	mode = user->intf->maintenance_mode;
 	spin_unlock_irqrestore(&user->intf->maintenance_mode_lock, flags);
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return mode;
 }
@@ -1543,11 +1540,11 @@ static void maintenance_mode_update(struct ipmi_smi *intf)
 
 int ipmi_set_maintenance_mode(struct ipmi_user *user, int mode)
 {
-	int rv = 0, index;
+	int rv = 0;
 	unsigned long flags;
 	struct ipmi_smi *intf = user->intf;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1577,7 +1574,7 @@ int ipmi_set_maintenance_mode(struct ipmi_user *user, int mode)
 	}
  out_unlock:
 	spin_unlock_irqrestore(&intf->maintenance_mode_lock, flags);
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1585,19 +1582,17 @@ EXPORT_SYMBOL(ipmi_set_maintenance_mode);
 
 int ipmi_set_gets_events(struct ipmi_user *user, bool val)
 {
-	unsigned long        flags;
 	struct ipmi_smi      *intf = user->intf;
 	struct ipmi_recv_msg *msg, *msg2;
 	struct list_head     msgs;
-	int index;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
 	INIT_LIST_HEAD(&msgs);
 
-	spin_lock_irqsave(&intf->events_lock, flags);
+	mutex_lock(&intf->events_mutex);
 	if (user->gets_events == val)
 		goto out;
 
@@ -1610,13 +1605,6 @@ int ipmi_set_gets_events(struct ipmi_user *user, bool val)
 		atomic_dec(&intf->event_waiters);
 	}
 
-	if (intf->delivering_events)
-		/*
-		 * Another thread is delivering events for this, so
-		 * let it handle any new events.
-		 */
-		goto out;
-
 	/* Deliver any queued events. */
 	while (user->gets_events && !list_empty(&intf->waiting_events)) {
 		list_for_each_entry_safe(msg, msg2, &intf->waiting_events, link)
@@ -1627,22 +1615,16 @@ int ipmi_set_gets_events(struct ipmi_user *user, bool val)
 			intf->event_msg_printed = 0;
 		}
 
-		intf->delivering_events = 1;
-		spin_unlock_irqrestore(&intf->events_lock, flags);
-
 		list_for_each_entry_safe(msg, msg2, &msgs, link) {
 			msg->user = user;
 			kref_get(&user->refcount);
 			deliver_local_response(intf, msg);
 		}
-
-		spin_lock_irqsave(&intf->events_lock, flags);
-		intf->delivering_events = 0;
 	}
 
  out:
-	spin_unlock_irqrestore(&intf->events_lock, flags);
-	release_ipmi_user(user, index);
+	mutex_unlock(&intf->events_mutex);
+	release_ipmi_user(user);
 
 	return 0;
 }
@@ -1687,9 +1669,9 @@ int ipmi_register_for_cmd(struct ipmi_user *user,
 {
 	struct ipmi_smi *intf = user->intf;
 	struct cmd_rcvr *rcvr;
-	int rv = 0, index;
+	int rv = 0;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1719,7 +1701,7 @@ out_unlock:
 	if (rv)
 		kfree(rcvr);
 out_release:
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 
 	return rv;
 }
@@ -1733,9 +1715,9 @@ int ipmi_unregister_for_cmd(struct ipmi_user *user,
 	struct ipmi_smi *intf = user->intf;
 	struct cmd_rcvr *rcvr;
 	struct cmd_rcvr *rcvrs = NULL;
-	int i, rv = -ENOENT, index;
+	int i, rv = -ENOENT;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -1758,7 +1740,7 @@ int ipmi_unregister_for_cmd(struct ipmi_user *user,
 	}
 	mutex_unlock(&intf->cmd_rcvrs_mutex);
 	synchronize_rcu();
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 	while (rcvrs) {
 		smi_remove_watch(intf, IPMI_WATCH_MASK_CHECK_COMMANDS);
 		rcvr = rcvrs;
@@ -1882,13 +1864,12 @@ static void smi_send(struct ipmi_smi *intf,
 		     const struct ipmi_smi_handlers *handlers,
 		     struct ipmi_smi_msg *smi_msg, int priority)
 {
-	int run_to_completion = intf->run_to_completion;
+	int run_to_completion = READ_ONCE(intf->run_to_completion);
 	unsigned long flags = 0;
 
 	if (!run_to_completion)
 		spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
 	smi_msg = smi_add_send_msg(intf, smi_msg, priority);
-
 	if (!run_to_completion)
 		spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
 
@@ -2304,6 +2285,7 @@ static int i_ipmi_request(struct ipmi_user     *user,
 {
 	struct ipmi_smi_msg *smi_msg;
 	struct ipmi_recv_msg *recv_msg;
+	int run_to_completion = READ_ONCE(intf->run_to_completion);
 	int rv = 0;
 
 	if (user) {
@@ -2337,7 +2319,8 @@ static int i_ipmi_request(struct ipmi_user     *user,
 		}
 	}
 
-	rcu_read_lock();
+	if (!run_to_completion)
+		mutex_lock(&intf->users_mutex);
 	if (intf->in_shutdown) {
 		rv = -ENODEV;
 		goto out_err;
@@ -2383,7 +2366,8 @@ out_err:
 
 		smi_send(intf, intf->handlers, smi_msg, priority);
 	}
-	rcu_read_unlock();
+	if (!run_to_completion)
+		mutex_unlock(&intf->users_mutex);
 
 out:
 	if (rv && user)
@@ -2414,12 +2398,12 @@ int ipmi_request_settime(struct ipmi_user *user,
 			 unsigned int     retry_time_ms)
 {
 	unsigned char saddr = 0, lun = 0;
-	int rv, index;
+	int rv;
 
 	if (!user)
 		return -EINVAL;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -2438,7 +2422,7 @@ int ipmi_request_settime(struct ipmi_user *user,
 				    retries,
 				    retry_time_ms);
 
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_request_settime);
@@ -2453,12 +2437,12 @@ int ipmi_request_supply_msgs(struct ipmi_user     *user,
 			     int                  priority)
 {
 	unsigned char saddr = 0, lun = 0;
-	int rv, index;
+	int rv;
 
 	if (!user)
 		return -EINVAL;
 
-	user = acquire_ipmi_user(user, &index);
+	user = acquire_ipmi_user(user);
 	if (!user)
 		return -ENODEV;
 
@@ -2477,7 +2461,7 @@ int ipmi_request_supply_msgs(struct ipmi_user     *user,
 				    lun,
 				    -1, 0);
 
-	release_ipmi_user(user, index);
+	release_ipmi_user(user);
 	return rv;
 }
 EXPORT_SYMBOL(ipmi_request_supply_msgs);
@@ -3064,7 +3048,7 @@ cleanup_bmc_device(struct kref *ref)
 	 * with removing the device attributes while reading a device
 	 * attribute.
 	 */
-	queue_work(remove_work_wq, &bmc->remove_work);
+	queue_work(bmc_remove_work_wq, &bmc->remove_work);
 }
 
 /*
@@ -3520,15 +3504,14 @@ static ssize_t nr_msgs_show(struct device *dev,
 			    char *buf)
 {
 	struct ipmi_smi *intf = container_of(attr,
-			 struct ipmi_smi, nr_msgs_devattr);
+					     struct ipmi_smi, nr_msgs_devattr);
 	struct ipmi_user *user;
-	int index;
 	unsigned int count = 0;
 
-	index = srcu_read_lock(&intf->users_srcu);
-	list_for_each_entry_rcu(user, &intf->users, link)
+	mutex_lock(&intf->users_mutex);
+	list_for_each_entry(user, &intf->users, link)
 		count += atomic_read(&user->nr_msgs);
-	srcu_read_unlock(&intf->users_srcu, index);
+	mutex_unlock(&intf->users_mutex);
 
 	return sysfs_emit(buf, "%u\n", count);
 }
@@ -3569,12 +3552,6 @@ int ipmi_add_smi(struct module         *owner,
 	if (!intf)
 		return -ENOMEM;
 
-	rv = init_srcu_struct(&intf->users_srcu);
-	if (rv) {
-		kfree(intf);
-		return rv;
-	}
-
 	intf->owner = owner;
 	intf->bmc = &intf->tmp_bmc;
 	INIT_LIST_HEAD(&intf->bmc->intfs);
@@ -3591,7 +3568,10 @@ int ipmi_add_smi(struct module         *owner,
 	}
 	if (slave_addr != 0)
 		intf->addrinfo[0].address = slave_addr;
+	INIT_LIST_HEAD(&intf->user_msgs);
+	mutex_init(&intf->user_msgs_mutex);
 	INIT_LIST_HEAD(&intf->users);
+	mutex_init(&intf->users_mutex);
 	atomic_set(&intf->nr_users, 0);
 	intf->handlers = handlers;
 	intf->send_info = send_info;
@@ -3603,12 +3583,12 @@ int ipmi_add_smi(struct module         *owner,
 	intf->curr_seq = 0;
 	spin_lock_init(&intf->waiting_rcv_msgs_lock);
 	INIT_LIST_HEAD(&intf->waiting_rcv_msgs);
-	INIT_WORK(&intf->recv_work, smi_recv_work);
+	INIT_WORK(&intf->smi_work, smi_work);
 	atomic_set(&intf->watchdog_pretimeouts_to_deliver, 0);
 	spin_lock_init(&intf->xmit_msgs_lock);
 	INIT_LIST_HEAD(&intf->xmit_msgs);
 	INIT_LIST_HEAD(&intf->hp_xmit_msgs);
-	spin_lock_init(&intf->events_lock);
+	mutex_init(&intf->events_mutex);
 	spin_lock_init(&intf->watch_lock);
 	atomic_set(&intf->event_waiters, 0);
 	intf->ticks_to_req_ev = IPMI_REQUEST_EV_TIME;
@@ -3621,12 +3601,16 @@ int ipmi_add_smi(struct module         *owner,
 	for (i = 0; i < IPMI_NUM_STATS; i++)
 		atomic_set(&intf->stats[i], 0);
 
+	/*
+	 * Grab the watchers mutex so we can deliver the new interface
+	 * without races.
+	 */
+	mutex_lock(&smi_watchers_mutex);
 	mutex_lock(&ipmi_interfaces_mutex);
 	/* Look for a hole in the numbers. */
 	i = 0;
 	link = &ipmi_interfaces;
-	list_for_each_entry_rcu(tintf, &ipmi_interfaces, link,
-				ipmi_interfaces_mutex_held()) {
+	list_for_each_entry(tintf, &ipmi_interfaces, link) {
 		if (tintf->intf_num != i) {
 			link = &tintf->link;
 			break;
@@ -3635,9 +3619,9 @@ int ipmi_add_smi(struct module         *owner,
 	}
 	/* Add the new interface in numeric order. */
 	if (i == 0)
-		list_add_rcu(&intf->link, &ipmi_interfaces);
+		list_add(&intf->link, &ipmi_interfaces);
 	else
-		list_add_tail_rcu(&intf->link, link);
+		list_add_tail(&intf->link, link);
 
 	rv = handlers->start_processing(send_info, intf);
 	if (rv)
@@ -3669,18 +3653,14 @@ int ipmi_add_smi(struct module         *owner,
 		goto out_err_bmc_reg;
 	}
 
-	/*
-	 * Keep memory order straight for RCU readers.  Make
-	 * sure everything else is committed to memory before
-	 * setting intf_num to mark the interface valid.
-	 */
-	smp_wmb();
 	intf->intf_num = i;
 	mutex_unlock(&ipmi_interfaces_mutex);
 
 	/* After this point the interface is legal to use. */
 	call_smi_watchers(i, intf->si_dev);
 
+	mutex_unlock(&smi_watchers_mutex);
+
 	return 0;
 
  out_err_bmc_reg:
@@ -3689,10 +3669,9 @@ int ipmi_add_smi(struct module         *owner,
 	if (intf->handlers->shutdown)
 		intf->handlers->shutdown(intf->send_info);
  out_err:
-	list_del_rcu(&intf->link);
+	list_del(&intf->link);
 	mutex_unlock(&ipmi_interfaces_mutex);
-	synchronize_srcu(&ipmi_interfaces_srcu);
-	cleanup_srcu_struct(&intf->users_srcu);
+	mutex_unlock(&smi_watchers_mutex);
 	kref_put(&intf->refcount, intf_free);
 
 	return rv;
@@ -3758,19 +3737,28 @@ static void cleanup_smi_msgs(struct ipmi_smi *intf)
 void ipmi_unregister_smi(struct ipmi_smi *intf)
 {
 	struct ipmi_smi_watcher *w;
-	int intf_num, index;
+	int intf_num;
 
 	if (!intf)
 		return;
+
 	intf_num = intf->intf_num;
 	mutex_lock(&ipmi_interfaces_mutex);
+	cancel_work_sync(&intf->smi_work);
+	/* smi_work() can no longer be in progress after this. */
+
 	intf->intf_num = -1;
 	intf->in_shutdown = true;
-	list_del_rcu(&intf->link);
+	list_del(&intf->link);
 	mutex_unlock(&ipmi_interfaces_mutex);
-	synchronize_srcu(&ipmi_interfaces_srcu);
 
-	/* At this point no users can be added to the interface. */
+	/*
+	 * At this point no users can be added to the interface and no
+	 * new messages can be sent.
+	 */
+
+	if (intf->handlers->shutdown)
+		intf->handlers->shutdown(intf->send_info);
 
 	device_remove_file(intf->si_dev, &intf->nr_msgs_devattr);
 	device_remove_file(intf->si_dev, &intf->nr_users_devattr);
@@ -3784,24 +3772,19 @@ void ipmi_unregister_smi(struct ipmi_smi *intf)
 		w->smi_gone(intf_num);
 	mutex_unlock(&smi_watchers_mutex);
 
-	index = srcu_read_lock(&intf->users_srcu);
+	mutex_lock(&intf->users_mutex);
 	while (!list_empty(&intf->users)) {
-		struct ipmi_user *user =
-			container_of(list_next_rcu(&intf->users),
-				     struct ipmi_user, link);
+		struct ipmi_user *user = list_first_entry(&intf->users,
+						    struct ipmi_user, link);
 
 		_ipmi_destroy_user(user);
 	}
-	srcu_read_unlock(&intf->users_srcu, index);
-
-	if (intf->handlers->shutdown)
-		intf->handlers->shutdown(intf->send_info);
+	mutex_unlock(&intf->users_mutex);
 
 	cleanup_smi_msgs(intf);
 
 	ipmi_bmc_unregister(intf);
 
-	cleanup_srcu_struct(&intf->users_srcu);
 	kref_put(&intf->refcount, intf_free);
 }
 EXPORT_SYMBOL(ipmi_unregister_smi);
@@ -3926,17 +3909,12 @@ static int handle_ipmb_get_msg_cmd(struct ipmi_smi *intf,
 		dev_dbg(intf->si_dev, "Invalid command: %*ph\n",
 			msg->data_size, msg->data);
 
-		rcu_read_lock();
-		if (!intf->in_shutdown) {
-			smi_send(intf, intf->handlers, msg, 0);
-			/*
-			 * We used the message, so return the value
-			 * that causes it to not be freed or
-			 * queued.
-			 */
-			rv = -1;
-		}
-		rcu_read_unlock();
+		smi_send(intf, intf->handlers, msg, 0);
+		/*
+		 * We used the message, so return the value that
+		 * causes it to not be freed or queued.
+		 */
+		rv = -1;
 	} else {
 		recv_msg = ipmi_alloc_recv_msg();
 		if (!recv_msg) {
@@ -3946,7 +3924,7 @@ static int handle_ipmb_get_msg_cmd(struct ipmi_smi *intf,
 			 * later.
 			 */
 			rv = 1;
-			kref_put(&user->refcount, free_user);
+			kref_put(&user->refcount, free_ipmi_user);
 		} else {
 			/* Extract the source address from the data. */
 			ipmb_addr = (struct ipmi_ipmb_addr *) &recv_msg->addr;
@@ -4017,17 +3995,12 @@ static int handle_ipmb_direct_rcv_cmd(struct ipmi_smi *intf,
 		msg->data[4] = IPMI_INVALID_CMD_COMPLETION_CODE;
 		msg->data_size = 5;
 
-		rcu_read_lock();
-		if (!intf->in_shutdown) {
-			smi_send(intf, intf->handlers, msg, 0);
-			/*
-			 * We used the message, so return the value
-			 * that causes it to not be freed or
-			 * queued.
-			 */
-			rv = -1;
-		}
-		rcu_read_unlock();
+		smi_send(intf, intf->handlers, msg, 0);
+		/*
+		 * We used the message, so return the value that
+		 * causes it to not be freed or queued.
+		 */
+		rv = -1;
 	} else {
 		recv_msg = ipmi_alloc_recv_msg();
 		if (!recv_msg) {
@@ -4037,7 +4010,7 @@ static int handle_ipmb_direct_rcv_cmd(struct ipmi_smi *intf,
 			 * later.
 			 */
 			rv = 1;
-			kref_put(&user->refcount, free_user);
+			kref_put(&user->refcount, free_ipmi_user);
 		} else {
 			/* Extract the source address from the data. */
 			daddr = (struct ipmi_ipmb_direct_addr *)&recv_msg->addr;
@@ -4206,14 +4179,33 @@ static int handle_lan_get_msg_cmd(struct ipmi_smi *intf,
 	rcu_read_unlock();
 
 	if (user == NULL) {
-		/* We didn't find a user, just give up. */
+		/* We didn't find a user, just give up and return an error. */
 		ipmi_inc_stat(intf, unhandled_commands);
 
+		msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
+		msg->data[1] = IPMI_SEND_MSG_CMD;
+		msg->data[2] = chan;
+		msg->data[3] = msg->rsp[4]; /* handle */
+		msg->data[4] = msg->rsp[8]; /* rsSWID */
+		msg->data[5] = ((netfn + 1) << 2) | (msg->rsp[9] & 0x3);
+		msg->data[6] = ipmb_checksum(&msg->data[3], 3);
+		msg->data[7] = msg->rsp[5]; /* rqSWID */
+		/* rqseq/lun */
+		msg->data[8] = (msg->rsp[9] & 0xfc) | (msg->rsp[6] & 0x3);
+		msg->data[9] = cmd;
+		msg->data[10] = IPMI_INVALID_CMD_COMPLETION_CODE;
+		msg->data[11] = ipmb_checksum(&msg->data[7], 4);
+		msg->data_size = 12;
+
+		dev_dbg(intf->si_dev, "Invalid command: %*ph\n",
+			msg->data_size, msg->data);
+
+		smi_send(intf, intf->handlers, msg, 0);
 		/*
-		 * Don't do anything with these messages, just allow
-		 * them to be freed.
+		 * We used the message, so return the value that
+		 * causes it to not be freed or queued.
 		 */
-		rv = 0;
+		rv = -1;
 	} else {
 		recv_msg = ipmi_alloc_recv_msg();
 		if (!recv_msg) {
@@ -4222,7 +4214,7 @@ static int handle_lan_get_msg_cmd(struct ipmi_smi *intf,
 			 * message, so requeue it for handling later.
 			 */
 			rv = 1;
-			kref_put(&user->refcount, free_user);
+			kref_put(&user->refcount, free_ipmi_user);
 		} else {
 			/* Extract the source address from the data. */
 			lan_addr = (struct ipmi_lan_addr *) &recv_msg->addr;
@@ -4331,7 +4323,7 @@ static int handle_oem_get_msg_cmd(struct ipmi_smi *intf,
 			 * later.
 			 */
 			rv = 1;
-			kref_put(&user->refcount, free_user);
+			kref_put(&user->refcount, free_ipmi_user);
 		} else {
 			/*
 			 * OEM Messages are expected to be delivered via
@@ -4393,8 +4385,7 @@ static int handle_read_event_rsp(struct ipmi_smi *intf,
 	struct ipmi_recv_msg *recv_msg, *recv_msg2;
 	struct list_head     msgs;
 	struct ipmi_user     *user;
-	int rv = 0, deliver_count = 0, index;
-	unsigned long        flags;
+	int rv = 0, deliver_count = 0;
 
 	if (msg->rsp_size < 19) {
 		/* Message is too small to be an IPMB event. */
@@ -4409,7 +4400,7 @@ static int handle_read_event_rsp(struct ipmi_smi *intf,
 
 	INIT_LIST_HEAD(&msgs);
 
-	spin_lock_irqsave(&intf->events_lock, flags);
+	mutex_lock(&intf->events_mutex);
 
 	ipmi_inc_stat(intf, events);
 
@@ -4417,18 +4408,20 @@ static int handle_read_event_rsp(struct ipmi_smi *intf,
 	 * Allocate and fill in one message for every user that is
 	 * getting events.
 	 */
-	index = srcu_read_lock(&intf->users_srcu);
-	list_for_each_entry_rcu(user, &intf->users, link) {
+	mutex_lock(&intf->users_mutex);
+	list_for_each_entry(user, &intf->users, link) {
 		if (!user->gets_events)
 			continue;
 
 		recv_msg = ipmi_alloc_recv_msg();
 		if (!recv_msg) {
-			rcu_read_unlock();
+			mutex_unlock(&intf->users_mutex);
 			list_for_each_entry_safe(recv_msg, recv_msg2, &msgs,
 						 link) {
+				user = recv_msg->user;
 				list_del(&recv_msg->link);
 				ipmi_free_recv_msg(recv_msg);
+				kref_put(&user->refcount, free_ipmi_user);
 			}
 			/*
 			 * We couldn't allocate memory for the
@@ -4446,7 +4439,7 @@ static int handle_read_event_rsp(struct ipmi_smi *intf,
 		kref_get(&user->refcount);
 		list_add_tail(&recv_msg->link, &msgs);
 	}
-	srcu_read_unlock(&intf->users_srcu, index);
+	mutex_unlock(&intf->users_mutex);
 
 	if (deliver_count) {
 		/* Now deliver all the messages. */
@@ -4484,7 +4477,7 @@ static int handle_read_event_rsp(struct ipmi_smi *intf,
 	}
 
  out:
-	spin_unlock_irqrestore(&intf->events_lock, flags);
+	mutex_unlock(&intf->events_mutex);
 
 	return rv;
 }
@@ -4570,7 +4563,7 @@ return_unspecified:
 	    && (msg->data[1] == IPMI_SEND_MSG_CMD)
 	    && (msg->user_data == NULL)) {
 
-		if (intf->in_shutdown)
+		if (intf->in_shutdown || intf->run_to_completion)
 			goto out;
 
 		/*
@@ -4642,6 +4635,9 @@ return_unspecified:
 		 */
 		struct ipmi_recv_msg *recv_msg;
 
+		if (intf->run_to_completion)
+			goto out;
+
 		chan = msg->data[2] & 0x0f;
 		if (chan >= IPMI_MAX_CHANNELS)
 			/* Invalid channel number */
@@ -4664,6 +4660,9 @@ process_response_response:
 		   && (msg->rsp[1] == IPMI_GET_MSG_CMD)) {
 		struct ipmi_channel   *chans;
 
+		if (intf->run_to_completion)
+			goto out;
+
 		/* It's from the receive queue. */
 		chan = msg->rsp[3] & 0xf;
 		if (chan >= IPMI_MAX_CHANNELS) {
@@ -4738,6 +4737,9 @@ process_response_response:
 	} else if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
 		   && (msg->rsp[1] == IPMI_READ_EVENT_MSG_BUFFER_CMD)) {
 		/* It's an asynchronous event. */
+		if (intf->run_to_completion)
+			goto out;
+
 		requeue = handle_read_event_rsp(intf, msg);
 	} else {
 		/* It's a response from the local BMC. */
@@ -4753,10 +4755,10 @@ process_response_response:
  */
 static void handle_new_recv_msgs(struct ipmi_smi *intf)
 {
-	struct ipmi_smi_msg  *smi_msg;
-	unsigned long        flags = 0;
-	int                  rv;
-	int                  run_to_completion = intf->run_to_completion;
+	struct ipmi_smi_msg *smi_msg;
+	unsigned long flags = 0;
+	int rv;
+	int run_to_completion = READ_ONCE(intf->run_to_completion);
 
 	/* See if any waiting messages need to be processed. */
 	if (!run_to_completion)
@@ -4790,31 +4792,15 @@ static void handle_new_recv_msgs(struct ipmi_smi *intf)
 	}
 	if (!run_to_completion)
 		spin_unlock_irqrestore(&intf->waiting_rcv_msgs_lock, flags);
-
-	/*
-	 * If the pretimout count is non-zero, decrement one from it and
-	 * deliver pretimeouts to all the users.
-	 */
-	if (atomic_add_unless(&intf->watchdog_pretimeouts_to_deliver, -1, 0)) {
-		struct ipmi_user *user;
-		int index;
-
-		index = srcu_read_lock(&intf->users_srcu);
-		list_for_each_entry_rcu(user, &intf->users, link) {
-			if (user->handler->ipmi_watchdog_pretimeout)
-				user->handler->ipmi_watchdog_pretimeout(
-					user->handler_data);
-		}
-		srcu_read_unlock(&intf->users_srcu, index);
-	}
 }
 
-static void smi_recv_work(struct work_struct *t)
+static void smi_work(struct work_struct *t)
 {
 	unsigned long flags = 0; /* keep us warning-free. */
-	struct ipmi_smi *intf = from_work(intf, t, recv_work);
-	int run_to_completion = intf->run_to_completion;
+	struct ipmi_smi *intf = from_work(intf, t, smi_work);
+	int run_to_completion = READ_ONCE(intf->run_to_completion);
 	struct ipmi_smi_msg *newmsg = NULL;
+	struct ipmi_recv_msg *msg, *msg2;
 
 	/*
 	 * Start the next message if available.
@@ -4824,8 +4810,6 @@ static void smi_recv_work(struct work_struct *t)
 	 * message delivery.
 	 */
 
-	rcu_read_lock();
-
 	if (!run_to_completion)
 		spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
 	if (intf->curr_msg == NULL && !intf->in_shutdown) {
@@ -4843,15 +4827,57 @@ static void smi_recv_work(struct work_struct *t)
 			intf->curr_msg = newmsg;
 		}
 	}
-
 	if (!run_to_completion)
 		spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
+
 	if (newmsg)
 		intf->handlers->sender(intf->send_info, newmsg);
 
-	rcu_read_unlock();
-
 	handle_new_recv_msgs(intf);
+
+	/* Nothing below applies during panic time. */
+	if (run_to_completion)
+		return;
+
+	/*
+	 * If the pretimout count is non-zero, decrement one from it and
+	 * deliver pretimeouts to all the users.
+	 */
+	if (atomic_add_unless(&intf->watchdog_pretimeouts_to_deliver, -1, 0)) {
+		struct ipmi_user *user;
+
+		mutex_lock(&intf->users_mutex);
+		list_for_each_entry(user, &intf->users, link) {
+			if (user->handler->ipmi_watchdog_pretimeout)
+				user->handler->ipmi_watchdog_pretimeout(
+					user->handler_data);
+		}
+		mutex_unlock(&intf->users_mutex);
+	}
+
+	/*
+	 * Freeing the message can cause a user to be released, which
+	 * can then cause the interface to be freed.  Make sure that
+	 * doesn't happen until we are ready.
+	 */
+	kref_get(&intf->refcount);
+
+	mutex_lock(&intf->user_msgs_mutex);
+	list_for_each_entry_safe(msg, msg2, &intf->user_msgs, link) {
+		struct ipmi_user *user = msg->user;
+
+		list_del(&msg->link);
+
+		if (refcount_read(&user->destroyed) == 0) {
+			ipmi_free_recv_msg(msg);
+		} else {
+			atomic_dec(&user->nr_msgs);
+			user->handler->ipmi_recv_hndl(msg, user->handler_data);
+		}
+	}
+	mutex_unlock(&intf->user_msgs_mutex);
+
+	kref_put(&intf->refcount, intf_free);
 }
 
 /* Handle a new message from the lower layer. */
@@ -4859,7 +4885,7 @@ void ipmi_smi_msg_received(struct ipmi_smi *intf,
 			   struct ipmi_smi_msg *msg)
 {
 	unsigned long flags = 0; /* keep us warning-free. */
-	int run_to_completion = intf->run_to_completion;
+	int run_to_completion = READ_ONCE(intf->run_to_completion);
 
 	/*
 	 * To preserve message order, we keep a queue and deliver from
@@ -4884,9 +4910,9 @@ void ipmi_smi_msg_received(struct ipmi_smi *intf,
 		spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
 
 	if (run_to_completion)
-		smi_recv_work(&intf->recv_work);
+		smi_work(&intf->smi_work);
 	else
-		queue_work(system_bh_wq, &intf->recv_work);
+		queue_work(system_wq, &intf->smi_work);
 }
 EXPORT_SYMBOL(ipmi_smi_msg_received);
 
@@ -4896,7 +4922,7 @@ void ipmi_smi_watchdog_pretimeout(struct ipmi_smi *intf)
 		return;
 
 	atomic_set(&intf->watchdog_pretimeouts_to_deliver, 1);
-	queue_work(system_bh_wq, &intf->recv_work);
+	queue_work(system_wq, &intf->smi_work);
 }
 EXPORT_SYMBOL(ipmi_smi_watchdog_pretimeout);
 
@@ -5065,7 +5091,7 @@ static bool ipmi_timeout_handler(struct ipmi_smi *intf,
 				       flags);
 	}
 
-	queue_work(system_bh_wq, &intf->recv_work);
+	queue_work(system_wq, &intf->smi_work);
 
 	return need_timer;
 }
@@ -5084,17 +5110,19 @@ static struct timer_list ipmi_timer;
 
 static atomic_t stop_operation;
 
-static void ipmi_timeout(struct timer_list *unused)
+static void ipmi_timeout_work(struct work_struct *work)
 {
+	if (atomic_read(&stop_operation))
+		return;
+
 	struct ipmi_smi *intf;
 	bool need_timer = false;
-	int index;
 
 	if (atomic_read(&stop_operation))
 		return;
 
-	index = srcu_read_lock(&ipmi_interfaces_srcu);
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+	mutex_lock(&ipmi_interfaces_mutex);
+	list_for_each_entry(intf, &ipmi_interfaces, link) {
 		if (atomic_read(&intf->event_waiters)) {
 			intf->ticks_to_req_ev--;
 			if (intf->ticks_to_req_ev == 0) {
@@ -5106,12 +5134,22 @@ static void ipmi_timeout(struct timer_list *unused)
 
 		need_timer |= ipmi_timeout_handler(intf, IPMI_TIMEOUT_TIME);
 	}
-	srcu_read_unlock(&ipmi_interfaces_srcu, index);
+	mutex_unlock(&ipmi_interfaces_mutex);
 
 	if (need_timer)
 		mod_timer(&ipmi_timer, jiffies + IPMI_TIMEOUT_JIFFIES);
 }
 
+static DECLARE_WORK(ipmi_timer_work, ipmi_timeout_work);
+
+static void ipmi_timeout(struct timer_list *unused)
+{
+	if (atomic_read(&stop_operation))
+		return;
+
+	queue_work(system_wq, &ipmi_timer_work);
+}
+
 static void need_waiter(struct ipmi_smi *intf)
 {
 	/* Racy, but worst case we start the timer twice. */
@@ -5168,7 +5206,7 @@ static struct ipmi_recv_msg *ipmi_alloc_recv_msg(void)
 void ipmi_free_recv_msg(struct ipmi_recv_msg *msg)
 {
 	if (msg->user && !oops_in_progress)
-		kref_put(&msg->user->refcount, free_user);
+		kref_put(&msg->user->refcount, free_ipmi_user);
 	msg->done(msg);
 }
 EXPORT_SYMBOL(ipmi_free_recv_msg);
@@ -5188,9 +5226,9 @@ static void dummy_recv_done_handler(struct ipmi_recv_msg *msg)
 /*
  * Inside a panic, send a message and wait for a response.
  */
-static void ipmi_panic_request_and_wait(struct ipmi_smi *intf,
-					struct ipmi_addr *addr,
-					struct kernel_ipmi_msg *msg)
+static void _ipmi_panic_request_and_wait(struct ipmi_smi *intf,
+					 struct ipmi_addr *addr,
+					 struct kernel_ipmi_msg *msg)
 {
 	struct ipmi_smi_msg  smi_msg;
 	struct ipmi_recv_msg recv_msg;
@@ -5220,6 +5258,15 @@ static void ipmi_panic_request_and_wait(struct ipmi_smi *intf,
 		ipmi_poll(intf);
 }
 
+void ipmi_panic_request_and_wait(struct ipmi_user *user,
+				 struct ipmi_addr *addr,
+				 struct kernel_ipmi_msg *msg)
+{
+	user->intf->run_to_completion = 1;
+	_ipmi_panic_request_and_wait(user->intf, addr, msg);
+}
+EXPORT_SYMBOL(ipmi_panic_request_and_wait);
+
 static void event_receiver_fetcher(struct ipmi_smi *intf,
 				   struct ipmi_recv_msg *msg)
 {
@@ -5288,7 +5335,7 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
 	}
 
 	/* Send the event announcing the panic. */
-	ipmi_panic_request_and_wait(intf, &addr, &msg);
+	_ipmi_panic_request_and_wait(intf, &addr, &msg);
 
 	/*
 	 * On every interface, dump a bunch of OEM event holding the
@@ -5324,7 +5371,7 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
 	msg.data = NULL;
 	msg.data_len = 0;
 	intf->null_user_handler = device_id_fetcher;
-	ipmi_panic_request_and_wait(intf, &addr, &msg);
+	_ipmi_panic_request_and_wait(intf, &addr, &msg);
 
 	if (intf->local_event_generator) {
 		/* Request the event receiver from the local MC. */
@@ -5333,7 +5380,7 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
 		msg.data = NULL;
 		msg.data_len = 0;
 		intf->null_user_handler = event_receiver_fetcher;
-		ipmi_panic_request_and_wait(intf, &addr, &msg);
+		_ipmi_panic_request_and_wait(intf, &addr, &msg);
 	}
 	intf->null_user_handler = NULL;
 
@@ -5385,7 +5432,7 @@ static void send_panic_events(struct ipmi_smi *intf, char *str)
 		memcpy_and_pad(data+5, 11, p, size, '\0');
 		p += size;
 
-		ipmi_panic_request_and_wait(intf, &addr, &msg);
+		_ipmi_panic_request_and_wait(intf, &addr, &msg);
 	}
 }
 
@@ -5403,7 +5450,7 @@ static int panic_event(struct notifier_block *this,
 	has_panicked = 1;
 
 	/* For every registered interface, set it to run to completion. */
-	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+	list_for_each_entry(intf, &ipmi_interfaces, link) {
 		if (!intf->handlers || intf->intf_num == -1)
 			/* Interface is not ready. */
 			continue;
@@ -5433,7 +5480,7 @@ static int panic_event(struct notifier_block *this,
 			intf->handlers->set_run_to_completion(intf->send_info,
 							      1);
 
-		list_for_each_entry_rcu(user, &intf->users, link) {
+		list_for_each_entry(user, &intf->users, link) {
 			if (user->handler->ipmi_panic_handler)
 				user->handler->ipmi_panic_handler(
 					user->handler_data);
@@ -5478,15 +5525,11 @@ static int ipmi_init_msghandler(void)
 	if (initialized)
 		goto out;
 
-	rv = init_srcu_struct(&ipmi_interfaces_srcu);
-	if (rv)
-		goto out;
-
-	remove_work_wq = create_singlethread_workqueue("ipmi-msghandler-remove-wq");
-	if (!remove_work_wq) {
+	bmc_remove_work_wq = create_singlethread_workqueue("ipmi-msghandler-remove-wq");
+	if (!bmc_remove_work_wq) {
 		pr_err("unable to create ipmi-msghandler-remove-wq workqueue");
 		rv = -ENOMEM;
-		goto out_wq;
+		goto out;
 	}
 
 	timer_setup(&ipmi_timer, ipmi_timeout, 0);
@@ -5496,9 +5539,6 @@ static int ipmi_init_msghandler(void)
 
 	initialized = true;
 
-out_wq:
-	if (rv)
-		cleanup_srcu_struct(&ipmi_interfaces_srcu);
 out:
 	mutex_unlock(&ipmi_interfaces_mutex);
 	return rv;
@@ -5522,7 +5562,7 @@ static void __exit cleanup_ipmi(void)
 	int count;
 
 	if (initialized) {
-		destroy_workqueue(remove_work_wq);
+		destroy_workqueue(bmc_remove_work_wq);
 
 		atomic_notifier_chain_unregister(&panic_notifier_list,
 						 &panic_block);
@@ -5539,6 +5579,7 @@ static void __exit cleanup_ipmi(void)
 		 */
 		atomic_set(&stop_operation, 1);
 		timer_delete_sync(&ipmi_timer);
+		cancel_work_sync(&ipmi_timer_work);
 
 		initialized = false;
 
@@ -5549,8 +5590,6 @@ static void __exit cleanup_ipmi(void)
 		count = atomic_read(&recv_msg_inuse_count);
 		if (count != 0)
 			pr_warn("recv message count %d at exit\n", count);
-
-		cleanup_srcu_struct(&ipmi_interfaces_srcu);
 	}
 	if (drvregistered)
 		driver_unregister(&ipmidriver.driver);
diff --git a/drivers/char/ipmi/ipmi_si.h b/drivers/char/ipmi/ipmi_si.h
index a7ead2a4c753..508c3fd45877 100644
--- a/drivers/char/ipmi/ipmi_si.h
+++ b/drivers/char/ipmi/ipmi_si.h
@@ -26,6 +26,14 @@ enum si_type {
 /* Array is defined in the ipmi_si_intf.c */
 extern const char *const si_to_str[];
 
+struct ipmi_match_info {
+	enum si_type type;
+};
+
+extern const struct ipmi_match_info ipmi_kcs_si_info;
+extern const struct ipmi_match_info ipmi_smic_si_info;
+extern const struct ipmi_match_info ipmi_bt_si_info;
+
 enum ipmi_addr_space {
 	IPMI_IO_ADDR_SPACE, IPMI_MEM_ADDR_SPACE
 };
@@ -64,7 +72,7 @@ struct si_sm_io {
 	void (*irq_cleanup)(struct si_sm_io *io);
 
 	u8 slave_addr;
-	enum si_type si_type;
+	const struct ipmi_match_info *si_info;
 	struct device *dev;
 };
 
diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 12b0b77eb1cc..7fe891783a37 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -73,6 +73,10 @@ enum si_intf_state {
 /* 'invalid' to allow a firmware-specified interface to be disabled */
 const char *const si_to_str[] = { "invalid", "kcs", "smic", "bt", NULL };
 
+const struct ipmi_match_info ipmi_kcs_si_info = { .type = SI_KCS };
+const struct ipmi_match_info ipmi_smic_si_info = { .type = SI_SMIC };
+const struct ipmi_match_info ipmi_bt_si_info = { .type = SI_BT };
+
 static bool initialized;
 
 /*
@@ -692,7 +696,7 @@ static void handle_transaction_done(struct smi_info *smi_info)
 			break;
 		}
 		enables = current_global_enables(smi_info, 0, &irq_on);
-		if (smi_info->io.si_type == SI_BT)
+		if (smi_info->io.si_info->type == SI_BT)
 			/* BT has its own interrupt enable bit. */
 			check_bt_irq(smi_info, irq_on);
 		if (enables != (msg[3] & GLOBAL_ENABLES_MASK)) {
@@ -1119,7 +1123,7 @@ irqreturn_t ipmi_si_irq_handler(int irq, void *data)
 	struct smi_info *smi_info = data;
 	unsigned long   flags;
 
-	if (smi_info->io.si_type == SI_BT)
+	if (smi_info->io.si_info->type == SI_BT)
 		/* We need to clear the IRQ flag for the BT interface. */
 		smi_info->io.outputb(&smi_info->io, IPMI_BT_INTMASK_REG,
 				     IPMI_BT_INTMASK_CLEAR_IRQ_BIT
@@ -1164,7 +1168,7 @@ static int smi_start_processing(void            *send_info,
 	 * The BT interface is efficient enough to not need a thread,
 	 * and there is no need for a thread if we have interrupts.
 	 */
-	else if ((new_smi->io.si_type != SI_BT) && (!new_smi->io.irq))
+	else if (new_smi->io.si_info->type != SI_BT && !new_smi->io.irq)
 		enable = 1;
 
 	if (enable) {
@@ -1235,7 +1239,7 @@ MODULE_PARM_DESC(kipmid_max_busy_us,
 
 void ipmi_irq_finish_setup(struct si_sm_io *io)
 {
-	if (io->si_type == SI_BT)
+	if (io->si_info->type == SI_BT)
 		/* Enable the interrupt in the BT interface. */
 		io->outputb(io, IPMI_BT_INTMASK_REG,
 			    IPMI_BT_INTMASK_ENABLE_IRQ_BIT);
@@ -1243,7 +1247,7 @@ void ipmi_irq_finish_setup(struct si_sm_io *io)
 
 void ipmi_irq_start_cleanup(struct si_sm_io *io)
 {
-	if (io->si_type == SI_BT)
+	if (io->si_info->type == SI_BT)
 		/* Disable the interrupt in the BT interface. */
 		io->outputb(io, IPMI_BT_INTMASK_REG, 0);
 }
@@ -1614,7 +1618,7 @@ static ssize_t type_show(struct device *dev,
 {
 	struct smi_info *smi_info = dev_get_drvdata(dev);
 
-	return sysfs_emit(buf, "%s\n", si_to_str[smi_info->io.si_type]);
+	return sysfs_emit(buf, "%s\n", si_to_str[smi_info->io.si_info->type]);
 }
 static DEVICE_ATTR_RO(type);
 
@@ -1649,7 +1653,7 @@ static ssize_t params_show(struct device *dev,
 
 	return sysfs_emit(buf,
 			"%s,%s,0x%lx,rsp=%d,rsi=%d,rsh=%d,irq=%d,ipmb=%d\n",
-			si_to_str[smi_info->io.si_type],
+			si_to_str[smi_info->io.si_info->type],
 			addr_space_to_str[smi_info->io.addr_space],
 			smi_info->io.addr_data,
 			smi_info->io.regspacing,
@@ -1803,7 +1807,7 @@ setup_dell_poweredge_bt_xaction_handler(struct smi_info *smi_info)
 {
 	struct ipmi_device_id *id = &smi_info->device_id;
 	if (id->manufacturer_id == DELL_IANA_MFR_ID &&
-	    smi_info->io.si_type == SI_BT)
+	    smi_info->io.si_info->type == SI_BT)
 		register_xaction_notifier(&dell_poweredge_bt_xaction_notifier);
 }
 
@@ -1907,13 +1911,13 @@ int ipmi_si_add_smi(struct si_sm_io *io)
 			/* We prefer ACPI over SMBIOS. */
 			dev_info(dup->io.dev,
 				 "Removing SMBIOS-specified %s state machine in favor of ACPI\n",
-				 si_to_str[new_smi->io.si_type]);
+				 si_to_str[new_smi->io.si_info->type]);
 			cleanup_one_si(dup);
 		} else {
 			dev_info(new_smi->io.dev,
 				 "%s-specified %s state machine: duplicate\n",
 				 ipmi_addr_src_to_str(new_smi->io.addr_source),
-				 si_to_str[new_smi->io.si_type]);
+				 si_to_str[new_smi->io.si_info->type]);
 			rv = -EBUSY;
 			kfree(new_smi);
 			goto out_err;
@@ -1922,7 +1926,7 @@ int ipmi_si_add_smi(struct si_sm_io *io)
 
 	pr_info("Adding %s-specified %s state machine\n",
 		ipmi_addr_src_to_str(new_smi->io.addr_source),
-		si_to_str[new_smi->io.si_type]);
+		si_to_str[new_smi->io.si_info->type]);
 
 	list_add_tail(&new_smi->link, &smi_infos);
 
@@ -1945,12 +1949,12 @@ static int try_smi_init(struct smi_info *new_smi)
 
 	pr_info("Trying %s-specified %s state machine at %s address 0x%lx, slave address 0x%x, irq %d\n",
 		ipmi_addr_src_to_str(new_smi->io.addr_source),
-		si_to_str[new_smi->io.si_type],
+		si_to_str[new_smi->io.si_info->type],
 		addr_space_to_str[new_smi->io.addr_space],
 		new_smi->io.addr_data,
 		new_smi->io.slave_addr, new_smi->io.irq);
 
-	switch (new_smi->io.si_type) {
+	switch (new_smi->io.si_info->type) {
 	case SI_KCS:
 		new_smi->handlers = &kcs_smi_handlers;
 		break;
@@ -2073,7 +2077,7 @@ static int try_smi_init(struct smi_info *new_smi)
 	smi_num++;
 
 	dev_info(new_smi->io.dev, "IPMI %s interface initialized\n",
-		 si_to_str[new_smi->io.si_type]);
+		 si_to_str[new_smi->io.si_info->type]);
 
 	WARN_ON(new_smi->io.dev->init_name != NULL);
 
@@ -2091,9 +2095,18 @@ static int try_smi_init(struct smi_info *new_smi)
 	return rv;
 }
 
+/*
+ * Devices in the same address space at the same address are the same.
+ */
+static bool __init ipmi_smi_info_same(struct smi_info *e1, struct smi_info *e2)
+{
+	return (e1->io.addr_space == e2->io.addr_space &&
+		e1->io.addr_data == e2->io.addr_data);
+}
+
 static int __init init_ipmi_si(void)
 {
-	struct smi_info *e;
+	struct smi_info *e, *e2;
 	enum ipmi_addr_src type = SI_INVALID;
 
 	if (initialized)
@@ -2109,37 +2122,70 @@ static int __init init_ipmi_si(void)
 
 	ipmi_si_parisc_init();
 
-	/* We prefer devices with interrupts, but in the case of a machine
-	   with multiple BMCs we assume that there will be several instances
-	   of a given type so if we succeed in registering a type then also
-	   try to register everything else of the same type */
 	mutex_lock(&smi_infos_lock);
+
+	/*
+	 * Scan through all the devices.  We prefer devices with
+	 * interrupts, so go through those first in case there are any
+	 * duplicates that don't have the interrupt set.
+	 */
 	list_for_each_entry(e, &smi_infos, link) {
-		/* Try to register a device if it has an IRQ and we either
-		   haven't successfully registered a device yet or this
-		   device has the same type as one we successfully registered */
-		if (e->io.irq && (!type || e->io.addr_source == type)) {
-			if (!try_smi_init(e)) {
-				type = e->io.addr_source;
+		bool dup = false;
+
+		/* Register ones with interrupts first. */
+		if (!e->io.irq)
+			continue;
+
+		/*
+		 * Go through the ones we have already seen to see if this
+		 * is a dup.
+		 */
+		list_for_each_entry(e2, &smi_infos, link) {
+			if (e2 == e)
+				break;
+			if (e2->io.irq && ipmi_smi_info_same(e, e2)) {
+				dup = true;
+				break;
 			}
 		}
+		if (!dup)
+			try_smi_init(e);
 	}
 
-	/* type will only have been set if we successfully registered an si */
-	if (type)
-		goto skip_fallback_noirq;
+	/*
+	 * Now try devices without interrupts.
+	 */
+	list_for_each_entry(e, &smi_infos, link) {
+		bool dup = false;
 
-	/* Fall back to the preferred device */
+		if (e->io.irq)
+			continue;
 
-	list_for_each_entry(e, &smi_infos, link) {
-		if (!e->io.irq && (!type || e->io.addr_source == type)) {
-			if (!try_smi_init(e)) {
-				type = e->io.addr_source;
+		/*
+		 * Go through the ones we have already seen to see if
+		 * this is a dup.  We have already looked at the ones
+		 * with interrupts.
+		 */
+		list_for_each_entry(e2, &smi_infos, link) {
+			if (!e2->io.irq)
+				continue;
+			if (ipmi_smi_info_same(e, e2)) {
+				dup = true;
+				break;
+			}
+		}
+		list_for_each_entry(e2, &smi_infos, link) {
+			if (e2 == e)
+				break;
+			if (ipmi_smi_info_same(e, e2)) {
+				dup = true;
+				break;
 			}
 		}
+		if (!dup)
+			try_smi_init(e);
 	}
 
-skip_fallback_noirq:
 	initialized = true;
 	mutex_unlock(&smi_infos_lock);
 
@@ -2267,7 +2313,7 @@ struct device *ipmi_si_remove_by_data(int addr_space, enum si_type si_type,
 	list_for_each_entry_safe(e, tmp_e, &smi_infos, link) {
 		if (e->io.addr_space != addr_space)
 			continue;
-		if (e->io.si_type != si_type)
+		if (e->io.si_info->type != si_type)
 			continue;
 		if (e->io.addr_data == addr) {
 			dev = get_device(e->io.dev);
diff --git a/drivers/char/ipmi/ipmi_si_parisc.c b/drivers/char/ipmi/ipmi_si_parisc.c
index 2be2967f6b5f..3b0a70d9adbb 100644
--- a/drivers/char/ipmi/ipmi_si_parisc.c
+++ b/drivers/char/ipmi/ipmi_si_parisc.c
@@ -13,7 +13,7 @@ static int __init ipmi_parisc_probe(struct parisc_device *dev)
 
 	memset(&io, 0, sizeof(io));
 
-	io.si_type	= SI_KCS;
+	io.si_info	= &ipmi_kcs_si_info;
 	io.addr_source	= SI_DEVICETREE;
 	io.addr_space	= IPMI_MEM_ADDR_SPACE;
 	io.addr_data	= dev->hpa.start;
diff --git a/drivers/char/ipmi/ipmi_si_pci.c b/drivers/char/ipmi/ipmi_si_pci.c
index 8c0ea637aba0..17f72763322d 100644
--- a/drivers/char/ipmi/ipmi_si_pci.c
+++ b/drivers/char/ipmi/ipmi_si_pci.c
@@ -23,30 +23,32 @@ MODULE_PARM_DESC(trypci,
 
 static int ipmi_pci_probe_regspacing(struct si_sm_io *io)
 {
-	if (io->si_type == SI_KCS) {
-		unsigned char	status;
-		int		regspacing;
-
-		io->regsize = DEFAULT_REGSIZE;
-		io->regshift = 0;
-
-		/* detect 1, 4, 16byte spacing */
-		for (regspacing = DEFAULT_REGSPACING; regspacing <= 16;) {
-			io->regspacing = regspacing;
-			if (io->io_setup(io)) {
-				dev_err(io->dev, "Could not setup I/O space\n");
-				return DEFAULT_REGSPACING;
-			}
-			/* write invalid cmd */
-			io->outputb(io, 1, 0x10);
-			/* read status back */
-			status = io->inputb(io, 1);
-			io->io_cleanup(io);
-			if (status)
-				return regspacing;
-			regspacing *= 4;
+	unsigned char status;
+	int regspacing;
+
+	if (io->si_info->type != SI_KCS)
+		return DEFAULT_REGSPACING;
+
+	io->regsize = DEFAULT_REGSIZE;
+	io->regshift = 0;
+
+	/* detect 1, 4, 16byte spacing */
+	for (regspacing = DEFAULT_REGSPACING; regspacing <= 16;) {
+		io->regspacing = regspacing;
+		if (io->io_setup(io)) {
+			dev_err(io->dev, "Could not setup I/O space\n");
+			return DEFAULT_REGSPACING;
 		}
+		/* write invalid cmd */
+		io->outputb(io, 1, 0x10);
+		/* read status back */
+		status = io->inputb(io, 1);
+		io->io_cleanup(io);
+		if (status)
+			return regspacing;
+		regspacing *= 4;
 	}
+
 	return DEFAULT_REGSPACING;
 }
 
@@ -74,15 +76,15 @@ static int ipmi_pci_probe(struct pci_dev *pdev,
 
 	switch (pdev->class) {
 	case PCI_CLASS_SERIAL_IPMI_SMIC:
-		io.si_type = SI_SMIC;
+		io.si_info = &ipmi_smic_si_info;
 		break;
 
 	case PCI_CLASS_SERIAL_IPMI_KCS:
-		io.si_type = SI_KCS;
+		io.si_info = &ipmi_kcs_si_info;
 		break;
 
 	case PCI_CLASS_SERIAL_IPMI_BT:
-		io.si_type = SI_BT;
+		io.si_info = &ipmi_bt_si_info;
 		break;
 
 	default:
diff --git a/drivers/char/ipmi/ipmi_si_platform.c b/drivers/char/ipmi/ipmi_si_platform.c
index 550cabd43ae6..fb6e359ae494 100644
--- a/drivers/char/ipmi/ipmi_si_platform.c
+++ b/drivers/char/ipmi/ipmi_si_platform.c
@@ -163,9 +163,13 @@ static int platform_ipmi_probe(struct platform_device *pdev)
 
 	switch (type) {
 	case SI_KCS:
+		io.si_info = &ipmi_kcs_si_info;
+		break;
 	case SI_SMIC:
+		io.si_info = &ipmi_smic_si_info;
+		break;
 	case SI_BT:
-		io.si_type = type;
+		io.si_info = &ipmi_bt_si_info;
 		break;
 	case SI_TYPE_INVALID: /* User disabled this in hardcode. */
 		return -ENODEV;
@@ -213,13 +217,10 @@ static int platform_ipmi_probe(struct platform_device *pdev)
 
 #ifdef CONFIG_OF
 static const struct of_device_id of_ipmi_match[] = {
-	{ .type = "ipmi", .compatible = "ipmi-kcs",
-	  .data = (void *)(unsigned long) SI_KCS },
-	{ .type = "ipmi", .compatible = "ipmi-smic",
-	  .data = (void *)(unsigned long) SI_SMIC },
-	{ .type = "ipmi", .compatible = "ipmi-bt",
-	  .data = (void *)(unsigned long) SI_BT },
-	{},
+	{ .type = "ipmi", .compatible = "ipmi-kcs", .data = &ipmi_kcs_si_info },
+	{ .type = "ipmi", .compatible = "ipmi-smic", .data = &ipmi_smic_si_info },
+	{ .type = "ipmi", .compatible = "ipmi-bt", .data = &ipmi_bt_si_info },
+	{}
 };
 MODULE_DEVICE_TABLE(of, of_ipmi_match);
 
@@ -265,7 +266,7 @@ static int of_ipmi_probe(struct platform_device *pdev)
 	}
 
 	memset(&io, 0, sizeof(io));
-	io.si_type	= (enum si_type)device_get_match_data(&pdev->dev);
+	io.si_info	= device_get_match_data(&pdev->dev);
 	io.addr_source	= SI_DEVICETREE;
 	io.irq_setup	= ipmi_std_irq_setup;
 
@@ -296,7 +297,7 @@ static int find_slave_address(struct si_sm_io *io, int slave_addr)
 {
 #ifdef CONFIG_IPMI_DMI_DECODE
 	if (!slave_addr)
-		slave_addr = ipmi_dmi_get_slave_addr(io->si_type,
+		slave_addr = ipmi_dmi_get_slave_addr(io->si_info->type,
 						     io->addr_space,
 						     io->addr_data);
 #endif
@@ -335,13 +336,13 @@ static int acpi_ipmi_probe(struct platform_device *pdev)
 
 	switch (tmp) {
 	case 1:
-		io.si_type = SI_KCS;
+		io.si_info = &ipmi_kcs_si_info;
 		break;
 	case 2:
-		io.si_type = SI_SMIC;
+		io.si_info = &ipmi_smic_si_info;
 		break;
 	case 3:
-		io.si_type = SI_BT;
+		io.si_info = &ipmi_bt_si_info;
 		break;
 	case 4: /* SSIF, just ignore */
 		return -ENODEV;
diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
index 0b45b07dec22..5bf038e620c7 100644
--- a/drivers/char/ipmi/ipmi_ssif.c
+++ b/drivers/char/ipmi/ipmi_ssif.c
@@ -481,8 +481,6 @@ static int ipmi_ssif_thread(void *data)
 		/* Wait for something to do */
 		result = wait_for_completion_interruptible(
 						&ssif_info->wake_thread);
-		if (ssif_info->stopping)
-			break;
 		if (result == -ERESTARTSYS)
 			continue;
 		init_completion(&ssif_info->wake_thread);
@@ -1270,10 +1268,8 @@ static void shutdown_ssif(void *send_info)
 	ssif_info->stopping = true;
 	timer_delete_sync(&ssif_info->watch_timer);
 	timer_delete_sync(&ssif_info->retry_timer);
-	if (ssif_info->thread) {
-		complete(&ssif_info->wake_thread);
+	if (ssif_info->thread)
 		kthread_stop(ssif_info->thread);
-	}
 }
 
 static void ssif_remove(struct i2c_client *client)
diff --git a/drivers/char/ipmi/ipmi_watchdog.c b/drivers/char/ipmi/ipmi_watchdog.c
index f1875b2bebbc..ab759b492fdd 100644
--- a/drivers/char/ipmi/ipmi_watchdog.c
+++ b/drivers/char/ipmi/ipmi_watchdog.c
@@ -150,7 +150,7 @@ static char preaction[16] = "pre_none";
 static unsigned char preop_val = WDOG_PREOP_NONE;
 
 static char preop[16] = "preop_none";
-static DEFINE_SPINLOCK(ipmi_read_lock);
+static DEFINE_MUTEX(ipmi_read_mutex);
 static char data_to_read;
 static DECLARE_WAIT_QUEUE_HEAD(read_q);
 static struct fasync_struct *fasync_q;
@@ -363,7 +363,7 @@ static int __ipmi_set_timeout(struct ipmi_smi_msg  *smi_msg,
 {
 	struct kernel_ipmi_msg            msg;
 	unsigned char                     data[6];
-	int                               rv;
+	int                               rv = 0;
 	struct ipmi_system_interface_addr addr;
 	int                               hbnow = 0;
 
@@ -405,14 +405,18 @@ static int __ipmi_set_timeout(struct ipmi_smi_msg  *smi_msg,
 	msg.cmd = IPMI_WDOG_SET_TIMER;
 	msg.data = data;
 	msg.data_len = sizeof(data);
-	rv = ipmi_request_supply_msgs(watchdog_user,
-				      (struct ipmi_addr *) &addr,
-				      0,
-				      &msg,
-				      NULL,
-				      smi_msg,
-				      recv_msg,
-				      1);
+	if (smi_msg)
+		rv = ipmi_request_supply_msgs(watchdog_user,
+					      (struct ipmi_addr *) &addr,
+					      0,
+					      &msg,
+					      NULL,
+					      smi_msg,
+					      recv_msg,
+					      1);
+	else
+		ipmi_panic_request_and_wait(watchdog_user,
+					    (struct ipmi_addr *) &addr, &msg);
 	if (rv)
 		pr_warn("set timeout error: %d\n", rv);
 	else if (send_heartbeat_now)
@@ -431,9 +435,7 @@ static int _ipmi_set_timeout(int do_heartbeat)
 
 	atomic_set(&msg_tofree, 2);
 
-	rv = __ipmi_set_timeout(&smi_msg,
-				&recv_msg,
-				&send_heartbeat_now);
+	rv = __ipmi_set_timeout(&smi_msg, &recv_msg, &send_heartbeat_now);
 	if (rv) {
 		atomic_set(&msg_tofree, 0);
 		return rv;
@@ -460,27 +462,10 @@ static int ipmi_set_timeout(int do_heartbeat)
 	return rv;
 }
 
-static atomic_t panic_done_count = ATOMIC_INIT(0);
-
-static void panic_smi_free(struct ipmi_smi_msg *msg)
-{
-	atomic_dec(&panic_done_count);
-}
-static void panic_recv_free(struct ipmi_recv_msg *msg)
-{
-	atomic_dec(&panic_done_count);
-}
-
-static struct ipmi_smi_msg panic_halt_heartbeat_smi_msg =
-	INIT_IPMI_SMI_MSG(panic_smi_free);
-static struct ipmi_recv_msg panic_halt_heartbeat_recv_msg =
-	INIT_IPMI_RECV_MSG(panic_recv_free);
-
 static void panic_halt_ipmi_heartbeat(void)
 {
 	struct kernel_ipmi_msg             msg;
 	struct ipmi_system_interface_addr addr;
-	int rv;
 
 	/*
 	 * Don't reset the timer if we have the timer turned off, that
@@ -497,24 +482,10 @@ static void panic_halt_ipmi_heartbeat(void)
 	msg.cmd = IPMI_WDOG_RESET_TIMER;
 	msg.data = NULL;
 	msg.data_len = 0;
-	atomic_add(2, &panic_done_count);
-	rv = ipmi_request_supply_msgs(watchdog_user,
-				      (struct ipmi_addr *) &addr,
-				      0,
-				      &msg,
-				      NULL,
-				      &panic_halt_heartbeat_smi_msg,
-				      &panic_halt_heartbeat_recv_msg,
-				      1);
-	if (rv)
-		atomic_sub(2, &panic_done_count);
+	ipmi_panic_request_and_wait(watchdog_user, (struct ipmi_addr *) &addr,
+				    &msg);
 }
 
-static struct ipmi_smi_msg panic_halt_smi_msg =
-	INIT_IPMI_SMI_MSG(panic_smi_free);
-static struct ipmi_recv_msg panic_halt_recv_msg =
-	INIT_IPMI_RECV_MSG(panic_recv_free);
-
 /*
  * Special call, doesn't claim any locks.  This is only to be called
  * at panic or halt time, in run-to-completion mode, when the caller
@@ -526,22 +497,13 @@ static void panic_halt_ipmi_set_timeout(void)
 	int send_heartbeat_now;
 	int rv;
 
-	/* Wait for the messages to be free. */
-	while (atomic_read(&panic_done_count) != 0)
-		ipmi_poll_interface(watchdog_user);
-	atomic_add(2, &panic_done_count);
-	rv = __ipmi_set_timeout(&panic_halt_smi_msg,
-				&panic_halt_recv_msg,
-				&send_heartbeat_now);
+	rv = __ipmi_set_timeout(NULL, NULL, &send_heartbeat_now);
 	if (rv) {
-		atomic_sub(2, &panic_done_count);
 		pr_warn("Unable to extend the watchdog timeout\n");
 	} else {
 		if (send_heartbeat_now)
 			panic_halt_ipmi_heartbeat();
 	}
-	while (atomic_read(&panic_done_count) != 0)
-		ipmi_poll_interface(watchdog_user);
 }
 
 static int __ipmi_heartbeat(void)
@@ -793,7 +755,7 @@ static ssize_t ipmi_read(struct file *file,
 	 * Reading returns if the pretimeout has gone off, and it only does
 	 * it once per pretimeout.
 	 */
-	spin_lock_irq(&ipmi_read_lock);
+	mutex_lock(&ipmi_read_mutex);
 	if (!data_to_read) {
 		if (file->f_flags & O_NONBLOCK) {
 			rv = -EAGAIN;
@@ -804,9 +766,9 @@ static ssize_t ipmi_read(struct file *file,
 		add_wait_queue(&read_q, &wait);
 		while (!data_to_read && !signal_pending(current)) {
 			set_current_state(TASK_INTERRUPTIBLE);
-			spin_unlock_irq(&ipmi_read_lock);
+			mutex_unlock(&ipmi_read_mutex);
 			schedule();
-			spin_lock_irq(&ipmi_read_lock);
+			mutex_lock(&ipmi_read_mutex);
 		}
 		remove_wait_queue(&read_q, &wait);
 
@@ -818,7 +780,7 @@ static ssize_t ipmi_read(struct file *file,
 	data_to_read = 0;
 
  out:
-	spin_unlock_irq(&ipmi_read_lock);
+	mutex_unlock(&ipmi_read_mutex);
 
 	if (rv == 0) {
 		if (copy_to_user(buf, &data_to_read, 1))
@@ -856,10 +818,10 @@ static __poll_t ipmi_poll(struct file *file, poll_table *wait)
 
 	poll_wait(file, &read_q, wait);
 
-	spin_lock_irq(&ipmi_read_lock);
+	mutex_lock(&ipmi_read_mutex);
 	if (data_to_read)
 		mask |= (EPOLLIN | EPOLLRDNORM);
-	spin_unlock_irq(&ipmi_read_lock);
+	mutex_unlock(&ipmi_read_mutex);
 
 	return mask;
 }
@@ -932,13 +894,11 @@ static void ipmi_wdog_pretimeout_handler(void *handler_data)
 			if (atomic_inc_and_test(&preop_panic_excl))
 				panic("Watchdog pre-timeout");
 		} else if (preop_val == WDOG_PREOP_GIVE_DATA) {
-			unsigned long flags;
-
-			spin_lock_irqsave(&ipmi_read_lock, flags);
+			mutex_lock(&ipmi_read_mutex);
 			data_to_read = 1;
 			wake_up_interruptible(&read_q);
 			kill_fasync(&fasync_q, SIGIO, POLL_IN);
-			spin_unlock_irqrestore(&ipmi_read_lock, flags);
+			mutex_unlock(&ipmi_read_mutex);
 		}
 	}
 
diff --git a/include/linux/ipmi.h b/include/linux/ipmi.h
index 2f74dd90c271..7da6602eab71 100644
--- a/include/linux/ipmi.h
+++ b/include/linux/ipmi.h
@@ -93,7 +93,8 @@ struct ipmi_user_hndl {
 
 	/*
 	 * Called when the interface detects a watchdog pre-timeout.  If
-	 * this is NULL, it will be ignored for the user.
+	 * this is NULL, it will be ignored for the user.  Note that you
+	 * can't do any IPMI calls from here, it's called with locks held.
 	 */
 	void (*ipmi_watchdog_pretimeout)(void *handler_data);
 
@@ -343,4 +344,14 @@ extern int ipmi_get_smi_info(int if_num, struct ipmi_smi_info *data);
 /* Helper function for computing the IPMB checksum of some data. */
 unsigned char ipmb_checksum(unsigned char *data, int size);
 
+/*
+ * For things that must send messages at panic time, like the IPMI watchdog
+ * driver that extends the reset time on a panic, use this to send messages
+ * from panic context.  Note that this puts the driver into a mode that
+ * only works at panic time, so only use it then.
+ */
+void ipmi_panic_request_and_wait(struct ipmi_user *user,
+				 struct ipmi_addr *addr,
+				 struct kernel_ipmi_msg *msg);
+
 #endif /* __LINUX_IPMI_H */