Messages in this thread Patch in this message | | | From | George Stark <> | Subject | [RFC PATCH 1/1] locking: introduce devm_mutex_init and devm_mutex_destroy | Date | Tue, 28 Nov 2023 03:09:10 +0300 |
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Using of devm API leads to certain order of releasing resources. So all dependent resources which are not devm-wrapped should be deleted with respect to devm-release order. Mutex is one of such objects that often is bound to other resources and has no own devm wrapping. Since mutex_destroy() actually does nothing in non-debug builds frequently calling mutex_destroy() is just ignored which is safe for now but wrong formally and can lead to a problem if mutex_destroy() will be extended so introduce devm_mutex_init() and devm_mutex_destroy().
Signed-off-by: George Stark <gnstark@salutedevices.com> --- include/linux/mutex.h | 3 +++ kernel/locking/mutex.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+)
diff --git a/include/linux/mutex.h b/include/linux/mutex.h index a33aa9eb9fc3..7f60cd842322 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -119,6 +119,9 @@ do { \ extern void __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key); +int devm_mutex_init(struct device *dev, struct mutex *lock); +void devm_mutex_destroy(struct device *dev, struct mutex *lock); + /** * mutex_is_locked - is the mutex locked * @lock: the mutex to be queried diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index d973fe6041bf..a73124719dcb 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -56,6 +56,43 @@ __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key) } EXPORT_SYMBOL(__mutex_init); +static void devm_mutex_release(struct device *dev, void *res) +{ + mutex_destroy(*(struct mutex **)res); +} + +static int devm_mutex_match(struct device *dev, void *res, void *data) +{ + struct mutex **r = res; + + if (WARN_ON(!r || !*r)) + return 0; + + return *r == data; +} + +int devm_mutex_init(struct device *dev, struct mutex *lock) +{ + struct mutex **ptr; + + ptr = devres_alloc(devm_mutex_release, sizeof(*ptr), GFP_KERNEL); + if (!ptr) + return -ENOMEM; + + mutex_init(lock); + + *ptr = lock; + devres_add(dev, ptr); + return 0; +} +EXPORT_SYMBOL(devm_mutex_init); + +void devm_mutex_destroy(struct device *dev, struct mutex *lock) +{ + devres_release(dev, devm_mutex_release, devm_mutex_match, lock); +} +EXPORT_SYMBOL(devm_mutex_destroy); + /* * @owner: contains: 'struct task_struct *' to the current lock owner, * NULL means not owned. Since task_struct pointers are aligned at -- 2.38.4
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