Re: [PATCH] locking/rtmutex: Annotate API and implementation

[Marco Elver]

On Sat, 2 May 2026 at 03:54, Bart Van Assche <bvanassche@xxxxxxx> wrote:
>
> Add lock context annotations to the rtmutex API and implementation and
> enable lock context analysis.
>
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>

If I'm not mistaken, Peter was working on this concurrently?
https://lore.kernel.org/all/20260121111213.851599178@xxxxxxxxxxxxx/ ?


> ---
>  include/linux/rtmutex.h      | 22 +++++++++++++++-------
>  kernel/locking/Makefile      |  1 +
>  kernel/locking/rtmutex.c     |  4 ++++
>  kernel/locking/rtmutex_api.c | 10 ++++++++--
>  4 files changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
> index 78e7e588817c..9e1f012f89db 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/Makefile b/kernel/locking/Makefile
> index cee1901d4cff..24dc00e12aa6 100644
> --- a/kernel/locking/Makefile
> +++ b/kernel/locking/Makefile
> @@ -4,6 +4,7 @@
>  KCOV_INSTRUMENT                := n
>
>  CONTEXT_ANALYSIS_mutex.o := y
> +CONTEXT_ANALYSIS_rtmutex.o := y
>  CONTEXT_ANALYSIS_rtmutex_api.o := y
>  CONTEXT_ANALYSIS_ww_rt_mutex.o := y
>  CONTEXT_ANALYSIS_rwsem.o := y
> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> index 4f386ea6c792..9147d6a31b78 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 124219aea46e..09675b9cb9bd 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;
>
> @@ -66,12 +67,14 @@ EXPORT_SYMBOL(rt_mutex_base_init);
>   * @subclass: the lockdep subclass
>   */
>  void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
> +       __no_context_analysis /* ignoring the return value below is fine in this case */
>  {
>         __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass);
>  }
>  EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
>
>  void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock)
> +       __no_context_analysis /* ignoring the return value below is fine in this case */
>  {
>         __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0);
>  }
> @@ -157,6 +160,7 @@ 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 +186,7 @@ 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 +317,7 @@ 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;
>
> @@ -526,7 +532,7 @@ static __always_inline int __mutex_lock_common(struct mutex *lock,
>                                                unsigned int subclass,
>                                                struct lockdep_map *nest_lock,
>                                                unsigned long ip)
> -       __acquires(lock) __no_context_analysis
> +       __acquires(lock)
>  {
>         int ret;
>
> @@ -648,7 +654,7 @@ EXPORT_SYMBOL(mutex_trylock);
>  #endif /* !CONFIG_DEBUG_LOCK_ALLOC */
>
>  void __sched mutex_unlock(struct mutex *lock)
> -       __releases(lock) __no_context_analysis
> +       __releases(lock)
>  {
>         mutex_release(&lock->dep_map, _RET_IP_);
>         __rt_mutex_unlock(&lock->rtmutex);