From 6957e1ac9c498ff934eaf1b7591b5ea1c98b6e54 Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Thu, 25 Jan 2007 11:22:24 +0100 Subject: USB: fix needless failure under certain conditions in devices.c we have a piece of code for dealing with losing in a race. If we indeed lose the race we don't care whether our own memory allocation worked. The check for that is so early that we return early even if we don't have to. Signed-off-by: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/devices.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'drivers/usb/core/devices.c') diff --git a/drivers/usb/core/devices.c b/drivers/usb/core/devices.c index a47c30b2d764..aefc7987120d 100644 --- a/drivers/usb/core/devices.c +++ b/drivers/usb/core/devices.c @@ -604,10 +604,6 @@ static unsigned int usb_device_poll(struct file *file, struct poll_table_struct lock_kernel(); if (!st) { st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL); - if (!st) { - unlock_kernel(); - return POLLIN; - } /* we may have dropped BKL - need to check for having lost the race */ if (file->private_data) { @@ -615,6 +611,11 @@ static unsigned int usb_device_poll(struct file *file, struct poll_table_struct st = file->private_data; goto lost_race; } + /* we haven't lost - check for allocation failure now */ + if (!st) { + unlock_kernel(); + return POLLIN; + } /* * need to prevent the module from being unloaded, since -- cgit v1.2.3 From 341487a837c02cbd674d4751061e7d098b0b8e98 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 9 Apr 2007 11:52:31 -0400 Subject: USB: remove use of the bus rwsem, as it doesn't really protect anything. The driver core stopped using the rwsem a long time ago, yet the USB core still grabbed the lock, thinking it protected something. This patch removes that useless use. Cc: Alan Stern Cc: Oliver Neukum Cc: David Brownell Cc: linux-usb-devel Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/devices.c | 2 -- drivers/usb/core/devio.c | 13 ------------- drivers/usb/core/driver.c | 12 ++++++------ drivers/usb/core/message.c | 2 +- 4 files changed, 7 insertions(+), 22 deletions(-) (limited to 'drivers/usb/core/devices.c') diff --git a/drivers/usb/core/devices.c b/drivers/usb/core/devices.c index aefc7987120d..6753ca059ee4 100644 --- a/drivers/usb/core/devices.c +++ b/drivers/usb/core/devices.c @@ -246,7 +246,6 @@ static char *usb_dump_interface_descriptor(char *start, char *end, if (start > end) return start; - down_read(&usb_bus_type.subsys.rwsem); if (iface) { driver_name = (iface->dev.driver ? iface->dev.driver->name @@ -263,7 +262,6 @@ static char *usb_dump_interface_descriptor(char *start, char *end, desc->bInterfaceSubClass, desc->bInterfaceProtocol, driver_name); - up_read(&usb_bus_type.subsys.rwsem); return start; } diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 36e7a843bf91..fc3545ddb06e 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -421,14 +421,11 @@ static int claimintf(struct dev_state *ps, unsigned int ifnum) if (test_bit(ifnum, &ps->ifclaimed)) return 0; - /* lock against other changes to driver bindings */ - down_write(&usb_bus_type.subsys.rwsem); intf = usb_ifnum_to_if(dev, ifnum); if (!intf) err = -ENOENT; else err = usb_driver_claim_interface(&usbfs_driver, intf, ps); - up_write(&usb_bus_type.subsys.rwsem); if (err == 0) set_bit(ifnum, &ps->ifclaimed); return err; @@ -444,8 +441,6 @@ static int releaseintf(struct dev_state *ps, unsigned int ifnum) if (ifnum >= 8*sizeof(ps->ifclaimed)) return err; dev = ps->dev; - /* lock against other changes to driver bindings */ - down_write(&usb_bus_type.subsys.rwsem); intf = usb_ifnum_to_if(dev, ifnum); if (!intf) err = -ENOENT; @@ -453,7 +448,6 @@ static int releaseintf(struct dev_state *ps, unsigned int ifnum) usb_driver_release_interface(&usbfs_driver, intf); err = 0; } - up_write(&usb_bus_type.subsys.rwsem); return err; } @@ -813,7 +807,6 @@ static int proc_getdriver(struct dev_state *ps, void __user *arg) if (copy_from_user(&gd, arg, sizeof(gd))) return -EFAULT; - down_read(&usb_bus_type.subsys.rwsem); intf = usb_ifnum_to_if(ps->dev, gd.interface); if (!intf || !intf->dev.driver) ret = -ENODATA; @@ -822,7 +815,6 @@ static int proc_getdriver(struct dev_state *ps, void __user *arg) sizeof(gd.driver)); ret = (copy_to_user(arg, &gd, sizeof(gd)) ? -EFAULT : 0); } - up_read(&usb_bus_type.subsys.rwsem); return ret; } @@ -1351,15 +1343,12 @@ static int proc_ioctl(struct dev_state *ps, struct usbdevfs_ioctl *ctl) /* disconnect kernel driver from interface */ case USBDEVFS_DISCONNECT: - - down_write(&usb_bus_type.subsys.rwsem); if (intf->dev.driver) { driver = to_usb_driver(intf->dev.driver); dev_dbg (&intf->dev, "disconnect by usbfs\n"); usb_driver_release_interface(driver, intf); } else retval = -ENODATA; - up_write(&usb_bus_type.subsys.rwsem); break; /* let kernel drivers try to (re)bind to the interface */ @@ -1371,7 +1360,6 @@ static int proc_ioctl(struct dev_state *ps, struct usbdevfs_ioctl *ctl) /* talk directly to the interface's driver */ default: - down_read(&usb_bus_type.subsys.rwsem); if (intf->dev.driver) driver = to_usb_driver(intf->dev.driver); if (driver == NULL || driver->ioctl == NULL) { @@ -1381,7 +1369,6 @@ static int proc_ioctl(struct dev_state *ps, struct usbdevfs_ioctl *ctl) if (retval == -ENOIOCTLCMD) retval = -ENOTTY; } - up_read(&usb_bus_type.subsys.rwsem); } /* cleanup and return */ diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index 9e3e943f313c..e6dd2b9210f6 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -287,9 +287,9 @@ static int usb_unbind_interface(struct device *dev) * way to bind to an interface is to return the private data from * the driver's probe() method. * - * Callers must own the device lock and the driver model's usb_bus_type.subsys - * writelock. So driver probe() entries don't need extra locking, - * but other call contexts may need to explicitly claim those locks. + * Callers must own the device lock, so driver probe() entries don't need + * extra locking, but other call contexts may need to explicitly claim that + * lock. */ int usb_driver_claim_interface(struct usb_driver *driver, struct usb_interface *iface, void* priv) @@ -330,9 +330,9 @@ EXPORT_SYMBOL(usb_driver_claim_interface); * also causes the driver disconnect() method to be called. * * This call is synchronous, and may not be used in an interrupt context. - * Callers must own the device lock and the driver model's usb_bus_type.subsys - * writelock. So driver disconnect() entries don't need extra locking, - * but other call contexts may need to explicitly claim those locks. + * Callers must own the device lock, so driver disconnect() entries don't + * need extra locking, but other call contexts may need to explicitly claim + * that lock. */ void usb_driver_release_interface(struct usb_driver *driver, struct usb_interface *iface) diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 217a3d6d0a06..c359ccb32998 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -1349,7 +1349,7 @@ static void release_interface(struct device *dev) * * This call is synchronous. The calling context must be able to sleep, * must own the device lock, and must not hold the driver model's USB - * bus rwsem; usb device driver probe() methods cannot use this routine. + * bus mutex; usb device driver probe() methods cannot use this routine. * * Returns zero on success, or else the status code returned by the * underlying call that failed. On successful completion, each interface -- cgit v1.2.3