Re: [Intel-gfx] [PATCH] drm/i915/guc: Use correct context lock when callig clr_context_registered

[Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>]

On 12/9/2021 10:48 AM, Matthew Brost wrote:
> s/ce/cn/ when grabbing guc_state.lock before calling
> clr_context_registered.
>
> Fixes: 0f7976506de61 ("drm/i915/guc: Rework and simplify locking")
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Cc: <stable@vger.kernel.org>

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>

I'm assuming we didn't see any splat from the lockdep assert in 
clr_context_registered in our CI runs because we never hit this case as 
it requires 64k+ contexts. Maybe we can add a selftest to purposely 
exercise this path? Not a blocker for merging this fix.

Daniele

> ---
>   drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 1f9d4fde421f..9b7b4f4e0d91 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -1937,9 +1937,9 @@ static int steal_guc_id(struct intel_guc *guc, struct intel_context *ce)
>   		list_del_init(&cn->guc_id.link);
>   		ce->guc_id = cn->guc_id;
>   
> -		spin_lock(&ce->guc_state.lock);
> +		spin_lock(&cn->guc_state.lock);
>   		clr_context_registered(cn);
> -		spin_unlock(&ce->guc_state.lock);
> +		spin_unlock(&cn->guc_state.lock);
>   
>   		set_context_guc_id_invalid(cn);
>