Re: [Intel-gfx] [PATCH] drm/i915/pmu: Check if pmu is closed before stopping event

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 19/10/2023 19:28, Umesh Nerlige Ramappa wrote:
> When the driver unbinds, pmu is unregistered and i915->uabi_engines is
> set to RB_ROOT. Due to this, when i915 PMU tries to stop the engine
> events, it issues a warn_on because engine lookup fails.
> 
> All perf hooks are taking care of this using a pmu->closed flag that is
> set when PMU unregisters. The stop event seems to have been left out.
> 
> Check for pmu->closed in pmu_event_stop as well.
> 
> Based on discussion here -
> https://patchwork.freedesktop.org/patch/492079/?series=105790&rev=2
> 
> v2: s/is/if/ in commit title
> 
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

Fixes: b00bccb3f0bb ("drm/i915/pmu: Handle PCI unbind")
Cc: <stable@vger.kernel.org> # v5.11+

> ---
>   drivers/gpu/drm/i915/i915_pmu.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index 108b675088ba..f861863eb7c1 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -831,9 +831,18 @@ static void i915_pmu_event_start(struct perf_event *event, int flags)
>   
>   static void i915_pmu_event_stop(struct perf_event *event, int flags)
>   {
> +	struct drm_i915_private *i915 =
> +		container_of(event->pmu, typeof(*i915), pmu.base);
> +	struct i915_pmu *pmu = &i915->pmu;
> +
> +	if (pmu->closed)
> +		goto out;
> +
>   	if (flags & PERF_EF_UPDATE)
>   		i915_pmu_event_read(event);
>   	i915_pmu_disable(event);
> +
> +out:
>   	event->hw.state = PERF_HES_STOPPED;
>   }
>   

You reminded me of this yesterday and it looks fine to me. Thanks for 
sending the fix!

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko