[PATCH] drm/i915: Add a warning on shutdown if signal threads still active

[PATCH] drm/i915: Add a warning on shutdown if signal threads still active

[Chris Wilson]

When unloading the module, it is expected that we have finished
executing all requests and so the signal threads should be idle. Add a
warning in case there are any residual requests in the signaler rbtrees
at that point.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_breadcrumbs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index c9c46a538edb..b7006e90a167 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -623,6 +623,8 @@ void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
 {
 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
 
+	WARN_ON(READ_ONCE(b->first_signal));
+	WARN_ON(!RB_EMPTY_ROOT(&b->signals));
 	if (!IS_ERR_OR_NULL(b->signaler))
 		kthread_stop(b->signaler);
 
-- 
2.10.2

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✓ Fi.CI.BAT: success for drm/i915: Add a warning on shutdown if signal threads still active

[Patchwork]

== Series Details ==

Series: drm/i915: Add a warning on shutdown if signal threads still active
URL   : https://patchwork.freedesktop.org/series/15641/
State : success

== Summary ==

Series 15641v1 drm/i915: Add a warning on shutdown if signal threads still active
https://patchwork.freedesktop.org/api/1.0/series/15641/revisions/1/mbox/


fi-bdw-5557u     total:244  pass:229  dwarn:0   dfail:0   fail:0   skip:15 
fi-bsw-n3050     total:244  pass:204  dwarn:0   dfail:0   fail:0   skip:40 
fi-bxt-t5700     total:244  pass:216  dwarn:0   dfail:0   fail:0   skip:28 
fi-byt-j1900     total:244  pass:216  dwarn:0   dfail:0   fail:0   skip:28 
fi-byt-n2820     total:244  pass:212  dwarn:0   dfail:0   fail:0   skip:32 
fi-hsw-4770      total:244  pass:224  dwarn:0   dfail:0   fail:0   skip:20 
fi-hsw-4770r     total:244  pass:224  dwarn:0   dfail:0   fail:0   skip:20 
fi-ilk-650       total:244  pass:191  dwarn:0   dfail:0   fail:0   skip:53 
fi-ivb-3520m     total:244  pass:222  dwarn:0   dfail:0   fail:0   skip:22 
fi-ivb-3770      total:244  pass:222  dwarn:0   dfail:0   fail:0   skip:22 
fi-kbl-7200u     total:244  pass:222  dwarn:0   dfail:0   fail:0   skip:22 
fi-skl-6260u     total:244  pass:230  dwarn:0   dfail:0   fail:0   skip:14 
fi-skl-6700hq    total:244  pass:223  dwarn:0   dfail:0   fail:0   skip:21 
fi-skl-6700k     total:244  pass:222  dwarn:1   dfail:0   fail:0   skip:21 
fi-skl-6770hq    total:244  pass:230  dwarn:0   dfail:0   fail:0   skip:14 
fi-snb-2520m     total:244  pass:212  dwarn:0   dfail:0   fail:0   skip:32 
fi-snb-2600      total:244  pass:211  dwarn:0   dfail:0   fail:0   skip:33 

accd56d36a298219042d84ba9ee1b7bd66d1936c drm-intel-nightly: 2016y-11m-18d-22h-35m-31s UTC integration manifest
9122fd0 drm/i915: Add a warning on shutdown if signal threads still active

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_3065/
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Re: [PATCH] drm/i915: Add a warning on shutdown if signal threads still active

[Tvrtko Ursulin]

On 21/11/2016 09:40, Chris Wilson wrote:
> When unloading the module, it is expected that we have finished
> executing all requests and so the signal threads should be idle. Add a
> warning in case there are any residual requests in the signaler rbtrees
> at that point.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_breadcrumbs.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> index c9c46a538edb..b7006e90a167 100644
> --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
> +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> @@ -623,6 +623,8 @@ void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
>  {
>  	struct intel_breadcrumbs *b = &engine->breadcrumbs;
>
> +	WARN_ON(READ_ONCE(b->first_signal));
> +	WARN_ON(!RB_EMPTY_ROOT(&b->signals));
>  	if (!IS_ERR_OR_NULL(b->signaler))
>  		kthread_stop(b->signaler);
>
>

Not sure if you are just testing out theories on the CI, but in any case 
looks to me it wouldn't harm to have this in.

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

Regards,

Tvrtko
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Re: [PATCH] drm/i915: Add a warning on shutdown if signal threads still active

[Chris Wilson]

On Mon, Nov 21, 2016 at 10:42:37AM +0000, Tvrtko Ursulin wrote:
> 
> On 21/11/2016 09:40, Chris Wilson wrote:
> >When unloading the module, it is expected that we have finished
> >executing all requests and so the signal threads should be idle. Add a
> >warning in case there are any residual requests in the signaler rbtrees
> >at that point.
> >
> >Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> >---
> > drivers/gpu/drm/i915/intel_breadcrumbs.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> >diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >index c9c46a538edb..b7006e90a167 100644
> >--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >@@ -623,6 +623,8 @@ void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
> > {
> > 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
> >
> >+	WARN_ON(READ_ONCE(b->first_signal));
> >+	WARN_ON(!RB_EMPTY_ROOT(&b->signals));
> > 	if (!IS_ERR_OR_NULL(b->signaler))
> > 		kthread_stop(b->signaler);
> >
> >
> 
> Not sure if you are just testing out theories on the CI, but in any
> case looks to me it wouldn't harm to have this in.

Only staring at the impossible, ruling out the unlikely. A leak here
would be caught by the request kmem_cache, but being explicit might help
in future.
 
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Imagine if I added a 

WARN_ON(READ_ONCE(b->first_waiter));
WARN_ON(!RB_EMPTY_ROOT(&b->waiters));

as well? Still r-b or go with a second patch for the afterthought?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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Re: [PATCH] drm/i915: Add a warning on shutdown if signal threads still active

[Tvrtko Ursulin]

On 21/11/2016 10:48, Chris Wilson wrote:
> On Mon, Nov 21, 2016 at 10:42:37AM +0000, Tvrtko Ursulin wrote:
>>
>> On 21/11/2016 09:40, Chris Wilson wrote:
>>> When unloading the module, it is expected that we have finished
>>> executing all requests and so the signal threads should be idle. Add a
>>> warning in case there are any residual requests in the signaler rbtrees
>>> at that point.
>>>
>>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>>> ---
>>> drivers/gpu/drm/i915/intel_breadcrumbs.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
>>> index c9c46a538edb..b7006e90a167 100644
>>> --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
>>> +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
>>> @@ -623,6 +623,8 @@ void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
>>> {
>>> 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
>>>
>>> +	WARN_ON(READ_ONCE(b->first_signal));
>>> +	WARN_ON(!RB_EMPTY_ROOT(&b->signals));
>>> 	if (!IS_ERR_OR_NULL(b->signaler))
>>> 		kthread_stop(b->signaler);
>>>
>>>
>>
>> Not sure if you are just testing out theories on the CI, but in any
>> case looks to me it wouldn't harm to have this in.
>
> Only staring at the impossible, ruling out the unlikely. A leak here
> would be caught by the request kmem_cache, but being explicit might help
> in future.
>
>> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> Imagine if I added a
>
> WARN_ON(READ_ONCE(b->first_waiter));
> WARN_ON(!RB_EMPTY_ROOT(&b->waiters));
>
> as well? Still r-b or go with a second patch for the afterthought?

It's the same thing conceptually so can expand and keep the r-b for what 
I am concerned.

Regards,

Tvrtko


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