Re: [RFC][PATCH 3/4] locking/rtmutex: Add context analysis

[Bart Van Assche]

On 1/21/26 3:07 AM, Peter Zijlstra wrote:
> Add compiler context analysis annotations.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
>   include/linux/mutex.h           |    2 +-
>   include/linux/rtmutex.h         |    4 ++--
>   kernel/locking/Makefile         |    2 ++
>   kernel/locking/mutex.c          |    2 --
>   kernel/locking/rtmutex.c        |   18 +++++++++++++++++-
>   kernel/locking/rtmutex_api.c    |    3 +++
>   kernel/locking/rtmutex_common.h |   22 ++++++++++++++++------
>   kernel/locking/ww_mutex.h       |   18 +++++++++++++-----
>   kernel/locking/ww_rt_mutex.c    |    1 +
>   9 files changed, 55 insertions(+), 17 deletions(-)

The patch subject says "rtmutex" but this patch includes a change for
the header file include/linux/mutex.h. Shouldn't that change be moved
into the mutex patch?

> --- a/kernel/locking/mutex.c
> +++ b/kernel/locking/mutex.c
> @@ -848,7 +848,6 @@ EXPORT_SYMBOL_GPL(mutex_lock_nested);
>   
>   void __sched
>   _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
> -	__acquires(lock)
>   {
>   	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);
>   	__acquire(lock);

Shouldn't the "__acquires()" annotation be moved to the declaration in
<linux/mutex.h>?

>   #define MUTEX		mutex
>   #define MUTEX_WAITER	mutex_waiter
> +#define MUST_HOLD_WAIT_LOCK	__must_hold(&lock->wait_lock)
>   
>   static inline struct mutex_waiter *
>   __ww_waiter_first(struct mutex *lock)
> @@ -97,9 +98,11 @@ static inline void lockdep_assert_wait_l
>   
>   #define MUTEX		rt_mutex
>   #define MUTEX_WAITER	rt_mutex_waiter
> +#define MUST_HOLD_WAIT_LOCK	__must_hold(&lock->rtmutex.wait_lock)

Is it really necessary to introduce these two macros? I prefer to see
the __must_hold() annotations instead of the macro names.

Thanks,

Bart.