From: Bart Van Assche Date: Fri, 8 May 2026 17:45:16 +0000 (-0700) Subject: locking/rtmutex: Annotate API and implementation X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=a9e4e50519e99e5be2d69fa4eebec6a4848ae201;p=thirdparty%2Flinux.git locking/rtmutex: Annotate API and implementation Enable context analysis for struct rt_mutex and annotate all functions that accept a struct rt_mutex pointer. In the __rt_mutex_lock_common() callers, instead of adding the __no_context_analysis annotation, emit a runtime warning if the __rt_mutex_lock_common() return value is not zero and add an __acquire() statement. Signed-off-by: Bart Van Assche Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260508174520.1416285-1-bvanassche@acm.org --- diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h index 78e7e588817cf..9e1f012f89db8 100644 --- a/include/linux/rtmutex.h +++ b/include/linux/rtmutex.h @@ -56,6 +56,8 @@ static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock) #endif extern void rt_mutex_base_init(struct rt_mutex_base *rtb); +context_lock_struct(rt_mutex); + /** * The rt_mutex structure * @@ -108,8 +110,10 @@ do { \ extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key); #ifdef CONFIG_DEBUG_LOCK_ALLOC -extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass); -extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock); +extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass) + __acquires(lock); +extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock) + __acquires(lock); #define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0) #define rt_mutex_lock_nest_lock(lock, nest_lock) \ do { \ @@ -118,15 +122,19 @@ extern void _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map * } while (0) #else -extern void rt_mutex_lock(struct rt_mutex *lock); +extern void rt_mutex_lock(struct rt_mutex *lock) __acquires(lock); #define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock) #define rt_mutex_lock_nest_lock(lock, nest_lock) rt_mutex_lock(lock) #endif -extern int rt_mutex_lock_interruptible(struct rt_mutex *lock); -extern int rt_mutex_lock_killable(struct rt_mutex *lock); -extern int rt_mutex_trylock(struct rt_mutex *lock); +extern int rt_mutex_lock_interruptible(struct rt_mutex *lock) + __cond_acquires(0, lock); +extern int rt_mutex_lock_killable(struct rt_mutex *lock) + __cond_acquires(0, lock); +extern int rt_mutex_trylock(struct rt_mutex *lock) + __cond_acquires(true, lock); -extern void rt_mutex_unlock(struct rt_mutex *lock); +extern void rt_mutex_unlock(struct rt_mutex *lock) + __releases(lock); #endif diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 4f386ea6c7928..9147d6a31b78c 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -484,6 +484,7 @@ static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_nod static __always_inline void rt_mutex_enqueue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter) + __must_hold(&lock->wait_lock) { lockdep_assert_held(&lock->wait_lock); @@ -492,6 +493,7 @@ rt_mutex_enqueue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter) static __always_inline void rt_mutex_dequeue(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter) + __must_hold(&lock->wait_lock) { lockdep_assert_held(&lock->wait_lock); @@ -1092,6 +1094,7 @@ static int __sched rt_mutex_adjust_prio_chain(struct task_struct *task, static int __sched try_to_take_rt_mutex(struct rt_mutex_base *lock, struct task_struct *task, struct rt_mutex_waiter *waiter) + __must_hold(&lock->wait_lock) { lockdep_assert_held(&lock->wait_lock); @@ -1319,6 +1322,7 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock, */ static void __sched mark_wakeup_next_waiter(struct rt_wake_q_head *wqh, struct rt_mutex_base *lock) + __must_hold(&lock->wait_lock) { struct rt_mutex_waiter *waiter; diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c index 124219aea46e4..7c40b91422a06 100644 --- a/kernel/locking/rtmutex_api.c +++ b/kernel/locking/rtmutex_api.c @@ -41,6 +41,7 @@ static __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock, unsigned int state, struct lockdep_map *nest_lock, unsigned int subclass) + __cond_acquires(0, lock) { int ret; @@ -67,13 +68,27 @@ EXPORT_SYMBOL(rt_mutex_base_init); */ void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass) { - __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass); + if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass) == 0) + return; + /* + * The code below is never reached because __rt_mutex_lock_common() only + * returns an error code if interrupted by a signal or upon a timeout. + */ + WARN_ON_ONCE(true); + __acquire(lock); } EXPORT_SYMBOL_GPL(rt_mutex_lock_nested); void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock) { - __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0); + if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0) == 0) + return; + /* + * The code below is never reached because __rt_mutex_lock_common() only + * returns an error code if interrupted by a signal or upon a timeout. + */ + WARN_ON_ONCE(true); + __acquire(lock); } EXPORT_SYMBOL_GPL(_rt_mutex_lock_nest_lock); @@ -86,7 +101,14 @@ EXPORT_SYMBOL_GPL(_rt_mutex_lock_nest_lock); */ void __sched rt_mutex_lock(struct rt_mutex *lock) { - __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0); + if (__rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0) == 0) + return; + /* + * The code below is never reached because __rt_mutex_lock_common() only + * returns an error code if interrupted by a signal or upon a timeout. + */ + WARN_ON_ONCE(true); + __acquire(lock); } EXPORT_SYMBOL_GPL(rt_mutex_lock); #endif @@ -157,6 +179,7 @@ void __sched rt_mutex_unlock(struct rt_mutex *lock) { mutex_release(&lock->dep_map, _RET_IP_); __rt_mutex_unlock(&lock->rtmutex); + __release(lock); } EXPORT_SYMBOL_GPL(rt_mutex_unlock); @@ -182,6 +205,7 @@ int __sched __rt_mutex_futex_trylock(struct rt_mutex_base *lock) */ bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock, struct rt_wake_q_head *wqh) + __must_hold(&lock->wait_lock) { lockdep_assert_held(&lock->wait_lock); @@ -312,6 +336,7 @@ int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter, struct task_struct *task, struct wake_q_head *wake_q) + __must_hold(&lock->wait_lock) { int ret;