Re: [PATCH 2/3] lockdep: add might_lock_nested()

[Peter Zijlstra]

On Tue, Aug 20, 2019 at 10:19:50AM +0200, Daniel Vetter wrote:
> Necessary to annotate functions where we might acquire a
> mutex_lock_nested() or similar. Needed by i915.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

> ---
>  include/linux/lockdep.h | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
> index 38ea6178df7d..30f6172d6889 100644
> --- a/include/linux/lockdep.h
> +++ b/include/linux/lockdep.h
> @@ -631,6 +631,13 @@ do {									\
>  	lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_);	\
>  	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
>  } while (0)
> +# define might_lock_nested(lock, subclass) 				\
> +do {									\
> +	typecheck(struct lockdep_map *, &(lock)->dep_map);		\
> +	lock_acquire(&(lock)->dep_map, subclass, 0, 1, 1, NULL,		\
> +		     _THIS_IP_);					\
> +	lock_release(&(lock)->dep_map, 0, _THIS_IP_);		\
> +} while (0)
>  
>  #define lockdep_assert_irqs_enabled()	do {				\
>  		WARN_ONCE(debug_locks && !current->lockdep_recursion &&	\
> @@ -653,6 +660,7 @@ do {									\
>  #else
>  # define might_lock(lock) do { } while (0)
>  # define might_lock_read(lock) do { } while (0)
> +# define might_lock_nested(lock, subclass) do { } while (0)
>  # define lockdep_assert_irqs_enabled() do { } while (0)
>  # define lockdep_assert_irqs_disabled() do { } while (0)
>  # define lockdep_assert_in_irq() do { } while (0)
> -- 
> 2.23.0.rc1
>