Re: [PATCH v2 3/3] lockdep: document MAX_LOCKDEP_CHAIN_HLOCKS calculation

[Waiman Long]

On 8/7/24 10:39, Carlos Llamas wrote:
> Define a macro AVG_LOCKDEP_CHAIN_DEPTH to document the magic number '5'
> used in the calculation of MAX_LOCKDEP_CHAIN_HLOCKS. The number
> represents the estimated average depth (number of locks held) of a lock
> chain. The calculation of MAX_LOCKDEP_CHAIN_HLOCKS was first added in
> commit 443cd507ce7f ("lockdep: add lock_class information to lock_chain
> and output it").
>
> Suggested-by: Waiman Long <longman@xxxxxxxxxx>
> Cc: Huang Ying <ying.huang@xxxxxxxxx>
> Cc: J. R. Okajima <hooanon05g@xxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
> ---
> v2: switched the comment for a macro as suggested by Waiman Long.
>
>   kernel/locking/lockdep_internals.h | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
> index bbe9000260d0..20f9ef58d3d0 100644
> --- a/kernel/locking/lockdep_internals.h
> +++ b/kernel/locking/lockdep_internals.h
> @@ -119,7 +119,8 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ =
>   
>   #define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
>   
> -#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
> +#define AVG_LOCKDEP_CHAIN_DEPTH		5
> +#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS * AVG_LOCKDEP_CHAIN_DEPTH)
>   
>   extern struct lock_chain lock_chains[];
>   
Acked-by: Waiman Long <longman@xxxxxxxxxx>