Re: [PATCH v5 07/36] lockdep: Annotate lockdep assertions for context analysis

[Bart Van Assche]

On 12/19/25 7:39 AM, Marco Elver wrote:
> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
> index dd634103b014..621566345406 100644
> --- a/include/linux/lockdep.h
> +++ b/include/linux/lockdep.h
> @@ -282,16 +282,16 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
>   	do { WARN_ON_ONCE(debug_locks && !(cond)); } while (0)
>   
>   #define lockdep_assert_held(l)		\
> -	lockdep_assert(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
> +	do { lockdep_assert(lockdep_is_held(l) != LOCK_STATE_NOT_HELD); __assume_ctx_lock(l); } while (0)
>   
>   #define lockdep_assert_not_held(l)	\
>   	lockdep_assert(lockdep_is_held(l) != LOCK_STATE_HELD)
>   
>   #define lockdep_assert_held_write(l)	\
> -	lockdep_assert(lockdep_is_held_type(l, 0))
> +	do { lockdep_assert(lockdep_is_held_type(l, 0)); __assume_ctx_lock(l); } while (0)
>   
>   #define lockdep_assert_held_read(l)	\
> -	lockdep_assert(lockdep_is_held_type(l, 1))
> +	do { lockdep_assert(lockdep_is_held_type(l, 1)); __assume_shared_ctx_lock(l); } while (0)
>   
>   #define lockdep_assert_held_once(l)		\
>   	lockdep_assert_once(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
> @@ -389,10 +389,10 @@ extern int lockdep_is_held(const void *);
>   #define lockdep_assert(c)			do { } while (0)
>   #define lockdep_assert_once(c)			do { } while (0)
>   
> -#define lockdep_assert_held(l)			do { (void)(l); } while (0)
> +#define lockdep_assert_held(l)			__assume_ctx_lock(l)
>   #define lockdep_assert_not_held(l)		do { (void)(l); } while (0)
> -#define lockdep_assert_held_write(l)		do { (void)(l); } while (0)
> -#define lockdep_assert_held_read(l)		do { (void)(l); } while (0)
> +#define lockdep_assert_held_write(l)		__assume_ctx_lock(l)
> +#define lockdep_assert_held_read(l)		__assume_shared_ctx_lock(l)
>   #define lockdep_assert_held_once(l)		do { (void)(l); } while (0)
>   #define lockdep_assert_none_held_once()	do { } while (0)

I think these macros should use __must_hold() instead of __assume...().
lockdep_assert_held() emits a runtime warning if 'l' is not held. Hence,
I think that code where lockdep_assert_held() is used should not compile
if it cannot be verified at compile time that 'l' is held.

Thanks,

Bart.