From fde25a9b63b9a3dc91365c394a426ebe64cfc2da Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 24 Jan 2012 13:34:24 -0500 Subject: Driver core: driver_find() drops reference before returning As part of the removal of get_driver()/put_driver(), this patch (as1510) changes driver_find(); it now drops the reference it acquires before returning. The patch also adjusts all the callers of driver_find() to remove the now unnecessary calls to put_driver(). In addition, the patch adds a warning to driver_find(): Callers must make sure the driver they are searching for does not get unloaded while they are using it. This has always been the case; driver_find() has never prevented a driver from being unregistered or unloaded. Hence the patch will not introduce any new bugs. The existing callers all seem to be okay in this respect, however I don't understand the video drivers well enough to be certain about them. Signed-off-by: Alan Stern CC: Dmitry Torokhov CC: Kyungmin Park CC: Andy Walls CC: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman --- drivers/base/driver.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers/base/driver.c') diff --git a/drivers/base/driver.c b/drivers/base/driver.c index b631f7c59453..e979cad75c6e 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -234,7 +234,6 @@ int driver_register(struct device_driver *drv) other = driver_find(drv->name, drv->bus); if (other) { - put_driver(other); printk(KERN_ERR "Error: Driver '%s' is already registered, " "aborting...\n", drv->name); return -EBUSY; @@ -275,7 +274,9 @@ EXPORT_SYMBOL_GPL(driver_unregister); * Call kset_find_obj() to iterate over list of drivers on * a bus to find driver by name. Return driver if found. * - * Note that kset_find_obj increments driver's reference count. + * This routine provides no locking to prevent the driver it returns + * from being unregistered or unloaded while the caller is using it. + * The caller is responsible for preventing this. */ struct device_driver *driver_find(const char *name, struct bus_type *bus) { @@ -283,6 +284,8 @@ struct device_driver *driver_find(const char *name, struct bus_type *bus) struct driver_private *priv; if (k) { + /* Drop reference added by kset_find_obj() */ + kobject_put(k); priv = to_driver(k); return priv->driver; } -- cgit v1.2.3 From 9875bb480cc89d9b690f7028aadf7e58454f0dae Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 24 Jan 2012 13:35:37 -0500 Subject: Eliminate get_driver() and put_driver() Now that there are no users of get_driver() or put_driver(), this patch (as1513) removes those routines completely. Signed-off-by: Alan Stern CC: Dmitry Torokhov Signed-off-by: Greg Kroah-Hartman --- drivers/base/driver.c | 28 ---------------------------- include/linux/device.h | 2 -- 2 files changed, 30 deletions(-) (limited to 'drivers/base/driver.c') diff --git a/drivers/base/driver.c b/drivers/base/driver.c index e979cad75c6e..60e4f77ca662 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -153,34 +153,6 @@ int driver_add_kobj(struct device_driver *drv, struct kobject *kobj, } EXPORT_SYMBOL_GPL(driver_add_kobj); -/** - * get_driver - increment driver reference count. - * @drv: driver. - */ -struct device_driver *get_driver(struct device_driver *drv) -{ - if (drv) { - struct driver_private *priv; - struct kobject *kobj; - - kobj = kobject_get(&drv->p->kobj); - priv = to_driver(kobj); - return priv->driver; - } - return NULL; -} -EXPORT_SYMBOL_GPL(get_driver); - -/** - * put_driver - decrement driver's refcount. - * @drv: driver. - */ -void put_driver(struct device_driver *drv) -{ - kobject_put(&drv->p->kobj); -} -EXPORT_SYMBOL_GPL(put_driver); - static int driver_add_groups(struct device_driver *drv, const struct attribute_group **groups) { diff --git a/include/linux/device.h b/include/linux/device.h index a782d7ff9e8b..d28bd8295677 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -238,8 +238,6 @@ struct device_driver { extern int __must_check driver_register(struct device_driver *drv); extern void driver_unregister(struct device_driver *drv); -extern struct device_driver *get_driver(struct device_driver *drv); -extern void put_driver(struct device_driver *drv); extern struct device_driver *driver_find(const char *name, struct bus_type *bus); extern int driver_probe_done(void); -- cgit v1.2.3 From fcd6f76202024763f2f4a348ab666240e4f7ac50 Mon Sep 17 00:00:00 2001 From: Stephen Rothwell Date: Wed, 7 Mar 2012 18:41:09 +0000 Subject: driver-core: remove legacy iSeries hack The PowerPC legacy iSeries plateform is being removed along with the "one looney iseries driver", so this code can now be removed as well. cc: Greg Kroah-Hartman Signed-off-by: Stephen Rothwell Signed-off-by: Benjamin Herrenschmidt --- drivers/base/driver.c | 30 ------------------------------ include/linux/device.h | 4 ---- 2 files changed, 34 deletions(-) (limited to 'drivers/base/driver.c') diff --git a/drivers/base/driver.c b/drivers/base/driver.c index b631f7c59453..db4f54c313aa 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -123,36 +123,6 @@ void driver_remove_file(struct device_driver *drv, } EXPORT_SYMBOL_GPL(driver_remove_file); -/** - * driver_add_kobj - add a kobject below the specified driver - * @drv: requesting device driver - * @kobj: kobject to add below this driver - * @fmt: format string that names the kobject - * - * You really don't want to do this, this is only here due to one looney - * iseries driver, go poke those developers if you are annoyed about - * this... - */ -int driver_add_kobj(struct device_driver *drv, struct kobject *kobj, - const char *fmt, ...) -{ - va_list args; - char *name; - int ret; - - va_start(args, fmt); - name = kvasprintf(GFP_KERNEL, fmt, args); - va_end(args); - - if (!name) - return -ENOMEM; - - ret = kobject_add(kobj, &drv->p->kobj, "%s", name); - kfree(name); - return ret; -} -EXPORT_SYMBOL_GPL(driver_add_kobj); - /** * get_driver - increment driver reference count. * @drv: driver. diff --git a/include/linux/device.h b/include/linux/device.h index b63fb393aa58..46baa1fec34c 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -264,10 +264,6 @@ extern int __must_check driver_create_file(struct device_driver *driver, extern void driver_remove_file(struct device_driver *driver, const struct driver_attribute *attr); -extern int __must_check driver_add_kobj(struct device_driver *drv, - struct kobject *kobj, - const char *fmt, ...); - extern int __must_check driver_for_each_device(struct device_driver *drv, struct device *start, void *data, -- cgit v1.2.3