Re: [PATCH] drm/radeon: Avoid double gpu reset by adding a timeout on IB ring tests.

[Christian König <deathsimple@xxxxxxxxxxx>]

Am 31.01.2016 um 19:50 schrieb Matthew Dawson:
> On Sunday, January 24, 2016 10:49:00 AM EST Christian König wrote:
> > Am 24.01.2016 um 07:18 schrieb Matthew Dawson:
> > > When the radeon driver resets a gpu, it attempts to test whether all the
> > > rings can successfully handle an IB.  If these rings fail to respond, the
> > > process will wait forever.  Another gpu reset can't happen at this point,
> > > as the current reset holds a lock required to do so.  Instead, make all
> > > the IB tests run with a timeout, so the system can attempt to recover
> > > in this case.
> > >
> > > While this doesn't fix the underlying issue with card resets failing, it
> > > gives the system a higher chance of recovering.  These timeouts have been
> > > confirmed to help both a Tathi and Hawaii card recover after a gpu reset.
> > >
> > > I haven't been able to test this on other cards, but everything compiles.
> > > I wasn't sure what to use for a timeout value, so for now I've used
> > > radeon_lockup_timeout.  When that is 0, the timeout functionality in this
> > > patch is also disabled.
> > >
> > > This also adds a new function, radeon_fence_wait_timeout, that behaves
> > > like
> > > radeon_fence_wait except allowing a different timeout value to be passed
> > > to
> > > radeon_fence_wait_seq_timeout.
> > >
> > > Signed-off-by: Matthew Dawson <matthew@xxxxxxxxxxxxx>
> > Really good idea, but please don't use radeon_lockup_timeout for this
> > cause the 10 seconds default of that is way to long. Instead just use a
> > fixed, let's say 100ms timeout defined in radeon.h.
> I originally tried 100ms, but I found that to be too short (my system would
> just lockup completely (no network even)).  I found 1s is long enough, and
> isn't so long to be annoying.  Would that be ok?

Yeah, 1s works as well. But that 100ms shouldn't be enough sounds like 
another bug to me.

> > Also don't define our own radeon_fence_wait_timeout, just use
> > fence_wait_timeout(&fence->base, RADEON_IB_TEST_TIMEOUT) for this.
> I switched everything over to this, however the ib test always times out after
> a gpu reset (on startup, everything is normal).  I'm not sure why
> fence_wait_timeout isn't being signaled while radeon_fence_wait_seq_timeout
> is.  I'm suspicious that either radeon_fence_enable_signaling is not doing
> something necessary to get the fence completion to actual signal
> radeon_fence_default_wait, or because we hold the exclusive lock during a
> reset radeon_fence_check_lockup never runs and thus never triggers the fence
> or enables some irq lines.
>
> Is it worth digging through the interactions here to get dma-buf fences to
> work correctly during a lockup, or would it be better to just keep
> radeon_fence_wait_timeout?  If option 1 is preferred, I'm happy to learn but I
> need some help learning how it is supposed to work.

In this case feel free to add the radeon_fence_wait_timeout. It's 
probably a good idea to get rid of the exclusive lock sooner or later in 
radeon as well, but that really is a long term project.

If you're really bored I can give you tons of input where to start with 
that.

Regards,
Christian.

> > Apart from that the idea looks really good to me.
> >
> > Regards,
> > Christian.
> Thanks,
>
> Matthew
>
> > > ---
> > >
> > >    drivers/gpu/drm/radeon/cik_sdma.c     |  3 ++-
> > >    drivers/gpu/drm/radeon/r100.c         |  3 ++-
> > >    drivers/gpu/drm/radeon/r600.c         |  3 ++-
> > >    drivers/gpu/drm/radeon/r600_dma.c     |  3 ++-
> > >    drivers/gpu/drm/radeon/radeon.h       |  1 +
> > >    drivers/gpu/drm/radeon/radeon_fence.c | 25 ++++++++++++++++++++++---
> > >    drivers/gpu/drm/radeon/radeon_vce.c   |  3 ++-
> > >    drivers/gpu/drm/radeon/uvd_v1_0.c     |  3 ++-
> > >    8 files changed, 35 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/radeon/cik_sdma.c
> > > b/drivers/gpu/drm/radeon/cik_sdma.c index d16f2ee..014f5ca 100644
> > > --- a/drivers/gpu/drm/radeon/cik_sdma.c
> > > +++ b/drivers/gpu/drm/radeon/cik_sdma.c
> > > @@ -737,7 +737,8 @@ int cik_sdma_ib_test(struct radeon_device *rdev,
> > > struct radeon_ring *ring)>
> > >    		DRM_ERROR("radeon: failed to schedule ib (%d).\n", r);
> > >    		return r;
> > >    	
> > >    	}
> > >
> > > -	r = radeon_fence_wait(ib.fence, false);
> > > +	r = radeon_fence_wait_timeout(ib.fence, false, msecs_to_jiffies(
> > > +		(radeon_lockup_timeout) ? radeon_lockup_timeout :
> > > MAX_SCHEDULE_TIMEOUT));>
> > >    	if (r) {
> > >    	
> > >    		DRM_ERROR("radeon: fence wait failed (%d).\n", r);
> > >    		return r;
> > >
> > > diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
> > > index 5eae0a8..5386c09 100644
> > > --- a/drivers/gpu/drm/radeon/r100.c
> > > +++ b/drivers/gpu/drm/radeon/r100.c
> > > @@ -3732,7 +3732,8 @@ int r100_ib_test(struct radeon_device *rdev, struct
> > > radeon_ring *ring)>
> > >    		DRM_ERROR("radeon: failed to schedule ib (%d).\n", r);
> > >    		goto free_ib;
> > >    	
> > >    	}
> > >
> > > -	r = radeon_fence_wait(ib.fence, false);
> > > +	r = radeon_fence_wait_timeout(ib.fence, false, msecs_to_jiffies(
> > > +		(radeon_lockup_timeout) ? radeon_lockup_timeout :
> > > MAX_SCHEDULE_TIMEOUT));>
> > >    	if (r) {
> > >    	
> > >    		DRM_ERROR("radeon: fence wait failed (%d).\n", r);
> > >    		goto free_ib;
> > >
> > > diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
> > > index cc2fdf0..8fbe5d7 100644
> > > --- a/drivers/gpu/drm/radeon/r600.c
> > > +++ b/drivers/gpu/drm/radeon/r600.c
> > > @@ -3381,7 +3381,8 @@ int r600_ib_test(struct radeon_device *rdev, struct
> > > radeon_ring *ring)>
> > >    		DRM_ERROR("radeon: failed to schedule ib (%d).\n", r);
> > >    		goto free_ib;
> > >    	
> > >    	}
> > >
> > > -	r = radeon_fence_wait(ib.fence, false);
> > > +	r = radeon_fence_wait_timeout(ib.fence, false, msecs_to_jiffies(
> > > +		(radeon_lockup_timeout) ? radeon_lockup_timeout :
> > > MAX_SCHEDULE_TIMEOUT));>
> > >    	if (r) {
> > >    	
> > >    		DRM_ERROR("radeon: fence wait failed (%d).\n", r);
> > >    		goto free_ib;
> > >
> > > diff --git a/drivers/gpu/drm/radeon/r600_dma.c
> > > b/drivers/gpu/drm/radeon/r600_dma.c index d2dd29a..3ff614d 100644
> > > --- a/drivers/gpu/drm/radeon/r600_dma.c
> > > +++ b/drivers/gpu/drm/radeon/r600_dma.c
> > > @@ -368,7 +368,8 @@ int r600_dma_ib_test(struct radeon_device *rdev,
> > > struct radeon_ring *ring)>
> > >    		DRM_ERROR("radeon: failed to schedule ib (%d).\n", r);
> > >    		return r;
> > >    	
> > >    	}
> > >
> > > -	r = radeon_fence_wait(ib.fence, false);
> > > +	r = radeon_fence_wait_timeout(ib.fence, false, msecs_to_jiffies(
> > > +		(radeon_lockup_timeout) ? radeon_lockup_timeout :
> > > MAX_SCHEDULE_TIMEOUT));>
> > >    	if (r) {
> > >    	
> > >    		DRM_ERROR("radeon: fence wait failed (%d).\n", r);
> > >    		return r;
> > >
> > > diff --git a/drivers/gpu/drm/radeon/radeon.h
> > > b/drivers/gpu/drm/radeon/radeon.h index 5ae6db9..0b698b6 100644
> > > --- a/drivers/gpu/drm/radeon/radeon.h
> > > +++ b/drivers/gpu/drm/radeon/radeon.h
> > > @@ -382,6 +382,7 @@ void radeon_fence_driver_force_completion(struct
> > > radeon_device *rdev, int ring);>
> > >    int radeon_fence_emit(struct radeon_device *rdev, struct radeon_fence
> > >    **fence, int ring); void radeon_fence_process(struct radeon_device
> > >    *rdev, int ring);
> > >    bool radeon_fence_signaled(struct radeon_fence *fence);
> > >
> > > +int radeon_fence_wait_timeout(struct radeon_fence *fence, bool
> > > interruptible, long timeout);>
> > >    int radeon_fence_wait(struct radeon_fence *fence, bool interruptible);
> > >    int radeon_fence_wait_next(struct radeon_device *rdev, int ring);
> > >    int radeon_fence_wait_empty(struct radeon_device *rdev, int ring);
> > >
> > > diff --git a/drivers/gpu/drm/radeon/radeon_fence.c
> > > b/drivers/gpu/drm/radeon/radeon_fence.c index 05815c4..9fec805 100644
> > > --- a/drivers/gpu/drm/radeon/radeon_fence.c
> > > +++ b/drivers/gpu/drm/radeon/radeon_fence.c
> > > @@ -527,7 +527,7 @@ static long radeon_fence_wait_seq_timeout(struct
> > > radeon_device *rdev,>
> > >    }
> > >    
> > >    /**
> > >
> > > - * radeon_fence_wait - wait for a fence to signal
> > > + * radeon_fence_wait_timeout - wait for a fence to signal with timeout
> > >
> > >     *
> > >     * @fence: radeon fence object
> > >     * @intr: use interruptible sleep
> > >
> > > @@ -535,9 +535,10 @@ static long radeon_fence_wait_seq_timeout(struct
> > > radeon_device *rdev,>
> > >     * Wait for the requested fence to signal (all asics).
> > >     * @intr selects whether to use interruptable (true) or
> > >     non-interruptable
> > >     * (false) sleep when waiting for the fence.
> > >
> > > + * @timeout: maximum time to wait, or MAX_SCHEDULE_TIMEOUT for infinite
> > > wait>
> > >     * Returns 0 if the fence has passed, error for all other cases.
> > >     */
> > >
> > > -int radeon_fence_wait(struct radeon_fence *fence, bool intr)
> > > +int radeon_fence_wait_timeout(struct radeon_fence *fence, bool intr, long
> > > timeout)>
> > >    {
> > >    
> > >    	uint64_t seq[RADEON_NUM_RINGS] = {};
> > >    	long r;
> > >
> > > @@ -552,9 +553,11 @@ int radeon_fence_wait(struct radeon_fence *fence,
> > > bool intr)>
> > >    		return fence_wait(&fence->base, intr);
> > >    	
> > >    	seq[fence->ring] = fence->seq;
> > >
> > > -	r = radeon_fence_wait_seq_timeout(fence->rdev, seq, intr,
> > > MAX_SCHEDULE_TIMEOUT); +	r = radeon_fence_wait_seq_timeout(fence->rdev,
> > > seq, intr, timeout);>
> > >    	if (r < 0) {
> > >    	
> > >    		return r;
> > >
> > > +	} else if (r == 0) {
> > > +		return -ETIMEDOUT;
> > >
> > >    	}
> > >    	
> > >    	r = fence_signal(&fence->base);
> > >
> > > @@ -564,6 +567,22 @@ int radeon_fence_wait(struct radeon_fence *fence,
> > > bool intr)>
> > >    }
> > >    
> > >    /**
> > >
> > > + * radeon_fence_wait - wait for a fence to signal
> > > + *
> > > + * @fence: radeon fence object
> > > + * @intr: use interruptible sleep
> > > + *
> > > + * Wait for the requested fence to signal (all asics).
> > > + * @intr selects whether to use interruptable (true) or non-interruptable
> > > + * (false) sleep when waiting for the fence.
> > > + * Returns 0 if the fence has passed, error for all other cases.
> > > + */
> > > +int radeon_fence_wait(struct radeon_fence *fence, bool intr)
> > > +{
> > > +	return radeon_fence_wait_timeout(fence, intr, MAX_SCHEDULE_TIMEOUT);
> > > +}
> > > +
> > > +/**
> > >
> > >     * radeon_fence_wait_any - wait for a fence to signal on any ring
> > >     *
> > >     * @rdev: radeon device pointer
> > >
> > > diff --git a/drivers/gpu/drm/radeon/radeon_vce.c
> > > b/drivers/gpu/drm/radeon/radeon_vce.c index 7eb1ae7..7d80dad 100644
> > > --- a/drivers/gpu/drm/radeon/radeon_vce.c
> > > +++ b/drivers/gpu/drm/radeon/radeon_vce.c
> > > @@ -810,7 +810,8 @@ int radeon_vce_ib_test(struct radeon_device *rdev,
> > > struct radeon_ring *ring)>
> > >    		goto error;
> > >    	
> > >    	}
> > >
> > > -	r = radeon_fence_wait(fence, false);
> > > +	r = radeon_fence_wait_timeout(fence, false, msecs_to_jiffies(
> > > +		(radeon_lockup_timeout) ? radeon_lockup_timeout :
> > > MAX_SCHEDULE_TIMEOUT));>
> > >    	if (r) {
> > >    	
> > >    		DRM_ERROR("radeon: fence wait failed (%d).\n", r);
> > >    	
> > >    	} else {
> > >
> > > diff --git a/drivers/gpu/drm/radeon/uvd_v1_0.c
> > > b/drivers/gpu/drm/radeon/uvd_v1_0.c index c6b1cbc..35caa89 100644
> > > --- a/drivers/gpu/drm/radeon/uvd_v1_0.c
> > > +++ b/drivers/gpu/drm/radeon/uvd_v1_0.c
> > > @@ -522,7 +522,8 @@ int uvd_v1_0_ib_test(struct radeon_device *rdev,
> > > struct radeon_ring *ring)>
> > >    		goto error;
> > >    	
> > >    	}
> > >
> > > -	r = radeon_fence_wait(fence, false);
> > > +	r = radeon_fence_wait_timeout(fence, false, msecs_to_jiffies(
> > > +		(radeon_lockup_timeout) ? radeon_lockup_timeout :
> > > MAX_SCHEDULE_TIMEOUT));>
> > >    	if (r) {
> > >    	
> > >    		DRM_ERROR("radeon: fence wait failed (%d).\n", r);
> > >    		goto error;

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