Am 09.09.22 um 19:08 schrieb Arvind Yadav:

Remove the signaled bit status check because it is returning early when the fence is already signaled and __dma_fence_enable_signaling is checking the status of signaled bit again.

Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com

Reviewed-by: Christian König christian.koenig@amd.com

---

Changes in v1, v2: This new patch was not part of previous series.

---

drivers/dma-buf/dma-fence.c | 3 --- 1 file changed, 3 deletions(-)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 066400ed8841..64c99739ad23 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -601,9 +601,6 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence) { unsigned long flags;

• if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))

• return;
  

• spin_lock_irqsave(fence->lock, flags); __dma_fence_enable_signaling(fence); spin_unlock_irqrestore(fence->lock, flags);

Am 09.09.22 um 19:08 schrieb Arvind Yadav:

Here's setting software signaling bit for the stub fence which is always signaled. If this fence signaling bit is not set then the AMD GPU scheduler will cause a GPU reset due to a GPU scheduler cleanup activity timeout.

Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com

Reviewed-by: Christian König christian.koenig@amd.com

---

Changes in v1 : 1- Addressing Christian's comment to remove unnecessary callback. 2- Replacing CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS. 3- The version of this patch is also changed and previously it was [PATCH 3/4]

Changes in v2 : 1 - perviously using __dma_fence_enable_signaling() for enable signaling. 2 - #ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH removed

---

drivers/dma-buf/dma-fence.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 64c99739ad23..bead1a6e9f59 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -136,6 +136,10 @@ struct dma_fence *dma_fence_get_stub(void) &dma_fence_stub_ops, &dma_fence_stub_lock, 0, 0);

• set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
  

• 	&dma_fence_stub.flags);
  

• dma_fence_signal_locked(&dma_fence_stub); } spin_unlock(&dma_fence_stub_lock);

Am 09.09.22 um 19:08 schrieb Arvind Yadav:

Here's enabling software signaling on fence for selftest.

Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com

Reviewed-by: Christian König christian.koenig@amd.com

---

Changes in v1 : 1- Addressing Christian's comment to remove unnecessary callback. 2- Replacing CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS. 3- The version of this patch is also changed and previously it was [PATCH 4/4]

Changes in v2 : 1- #ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH removed

---

drivers/dma-buf/st-dma-fence-chain.c | 4 ++++ drivers/dma-buf/st-dma-fence-unwrap.c | 22 ++++++++++++++++++++++ drivers/dma-buf/st-dma-fence.c | 16 ++++++++++++++++ drivers/dma-buf/st-dma-resv.c | 10 ++++++++++ 4 files changed, 52 insertions(+)

diff --git a/drivers/dma-buf/st-dma-fence-chain.c b/drivers/dma-buf/st-dma-fence-chain.c index 8ce1ea59d31b..0a9b099d0518 100644 --- a/drivers/dma-buf/st-dma-fence-chain.c +++ b/drivers/dma-buf/st-dma-fence-chain.c @@ -87,6 +87,8 @@ static int sanitycheck(void *arg) if (!chain) err = -ENOMEM;

• dma_fence_enable_sw_signaling(chain);
• dma_fence_signal(f); dma_fence_put(f);

@@ -143,6 +145,8 @@ static int fence_chains_init(struct fence_chains *fc, unsigned int count, } fc->tail = fc->chains[i];

• dma_fence_enable_sw_signaling(fc->chains[i]);
  

  }

fc->chain_length = i; diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c index 4105d5ea8dde..f0cee984b6c7 100644 --- a/drivers/dma-buf/st-dma-fence-unwrap.c +++ b/drivers/dma-buf/st-dma-fence-unwrap.c @@ -102,6 +102,8 @@ static int sanitycheck(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• array = mock_array(1, f); if (!array) return -ENOMEM;

@@ -124,12 +126,16 @@ static int unwrap_array(void *arg) if (!f1) return -ENOMEM;

• dma_fence_enable_sw_signaling(f1);
• f2 = mock_fence(); if (!f2) { dma_fence_put(f1); return -ENOMEM; }

• dma_fence_enable_sw_signaling(f2);
• array = mock_array(2, f1, f2); if (!array) return -ENOMEM;

@@ -164,12 +170,16 @@ static int unwrap_chain(void *arg) if (!f1) return -ENOMEM;

• dma_fence_enable_sw_signaling(f1);
• f2 = mock_fence(); if (!f2) { dma_fence_put(f1); return -ENOMEM; }

• dma_fence_enable_sw_signaling(f2);
• chain = mock_chain(f1, f2); if (!chain) return -ENOMEM;

@@ -204,12 +214,16 @@ static int unwrap_chain_array(void *arg) if (!f1) return -ENOMEM;

• dma_fence_enable_sw_signaling(f1);
• f2 = mock_fence(); if (!f2) { dma_fence_put(f1); return -ENOMEM; }

• dma_fence_enable_sw_signaling(f2);
• array = mock_array(2, f1, f2); if (!array) return -ENOMEM;

@@ -248,12 +262,16 @@ static int unwrap_merge(void *arg) if (!f1) return -ENOMEM;

• dma_fence_enable_sw_signaling(f1);
• f2 = mock_fence(); if (!f2) { err = -ENOMEM; goto error_put_f1; }

• dma_fence_enable_sw_signaling(f2);
• f3 = dma_fence_unwrap_merge(f1, f2); if (!f3) { err = -ENOMEM;

@@ -296,10 +314,14 @@ static int unwrap_merge_complex(void *arg) if (!f1) return -ENOMEM;

• dma_fence_enable_sw_signaling(f1);
• f2 = mock_fence(); if (!f2) goto error_put_f1;

• dma_fence_enable_sw_signaling(f2);
• f3 = dma_fence_unwrap_merge(f1, f2); if (!f3) goto error_put_f2;

diff --git a/drivers/dma-buf/st-dma-fence.c b/drivers/dma-buf/st-dma-fence.c index c8a12d7ad71a..fb6e0a6ae2c9 100644 --- a/drivers/dma-buf/st-dma-fence.c +++ b/drivers/dma-buf/st-dma-fence.c @@ -102,6 +102,8 @@ static int sanitycheck(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_fence_signal(f); dma_fence_put(f);

@@ -117,6 +119,8 @@ static int test_signaling(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• if (dma_fence_is_signaled(f)) { pr_err("Fence unexpectedly signaled on creation\n"); goto err_free;

@@ -190,6 +194,8 @@ static int test_late_add_callback(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_fence_signal(f);

if (!dma_fence_add_callback(f, &cb.cb, simple_callback)) { @@ -282,6 +288,8 @@ static int test_status(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• if (dma_fence_get_status(f)) { pr_err("Fence unexpectedly has signaled status on creation\n"); goto err_free;

@@ -308,6 +316,8 @@ static int test_error(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_fence_set_error(f, -EIO);

if (dma_fence_get_status(f)) { @@ -337,6 +347,8 @@ static int test_wait(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• if (dma_fence_wait_timeout(f, false, 0) != -ETIME) { pr_err("Wait reported complete before being signaled\n"); goto err_free;

@@ -379,6 +391,8 @@ static int test_wait_timeout(void *arg) if (!wt.f) return -ENOMEM;

• dma_fence_enable_sw_signaling(wt.f);
• if (dma_fence_wait_timeout(wt.f, false, 1) != -ETIME) { pr_err("Wait reported complete before being signaled\n"); goto err_free;

@@ -458,6 +472,8 @@ static int thread_signal_callback(void *arg) break; }

• dma_fence_enable_sw_signaling(f1);
  

• rcu_assign_pointer(t->fences[t->id], f1); smp_wmb();

diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c index 813779e3c9be..15dbea1462ed 100644 --- a/drivers/dma-buf/st-dma-resv.c +++ b/drivers/dma-buf/st-dma-resv.c @@ -45,6 +45,8 @@ static int sanitycheck(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_fence_signal(f); dma_fence_put(f);

@@ -69,6 +71,8 @@ static int test_signaling(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_resv_init(&resv); r = dma_resv_lock(&resv, NULL); if (r) {

@@ -114,6 +118,8 @@ static int test_for_each(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_resv_init(&resv); r = dma_resv_lock(&resv, NULL); if (r) {

@@ -173,6 +179,8 @@ static int test_for_each_unlocked(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_resv_init(&resv); r = dma_resv_lock(&resv, NULL); if (r) {

@@ -244,6 +252,8 @@ static int test_get_fences(void *arg) if (!f) return -ENOMEM;

• dma_fence_enable_sw_signaling(f);
• dma_resv_init(&resv); r = dma_resv_lock(&resv, NULL); if (r) {

Am 09.09.22 um 19:08 schrieb Arvind Yadav:

Here's enabling software signaling on fence because amdgpu_ctx_add_fence() is checking the status of fence and emits warning.

Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com

Changes in v1, v2: This new patch was not part of previous series.

---

drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c index afe22f83d4a6..21221d705588 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c @@ -730,6 +730,8 @@ uint64_t amdgpu_ctx_add_fence(struct amdgpu_ctx *ctx, dma_fence_get(fence);

• dma_fence_enable_sw_signaling(fence);

That looks like a step into the right direction, but still isn't correct.

The code using this interface should call amdgpu_ctx_wait_prev_fence() before calling amdgpu_ctx_add_fence(). And amdgpu_ctx_wait_prev_fence() in turn calls dma_fence_wait() which should also enables the signaling.

So when we need this here something is still very wrong on the logic :)

Thanks, Christian.

spin_lock(&ctx->ring_lock); centity->fences[idx] = fence; centity->sequence++;

What exactly is the scenario which this patch fixes in more detail please  ?

Andrey

On 2022-09-09 13:08, Arvind Yadav wrote:

Using the parent fence instead of the finished fence to get the job status. This change is to avoid GPU scheduler timeout error which can cause GPU reset.

Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com

changes in v1,v2 - Enable signaling for finished fence in sche_main() is removed

---

drivers/gpu/drm/scheduler/sched_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index e0ab14e0fb6b..2ac28ad11432 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -829,7 +829,7 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched) job = list_first_entry_or_null(&sched->pending_list, struct drm_sched_job, list);

• if (job && dma_fence_is_signaled(&job->s_fence->finished)) {

• if (job && dma_fence_is_signaled(job->s_fence->parent)) { /* remove job from pending_list */ list_del_init(&job->list);

@@ -841,7 +841,7 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched) if (next) { next->s_fence->scheduled.timestamp =

• 		job->s_fence->finished.timestamp;
  

• 		job->s_fence->parent->timestamp;
  /* start TO timer for next job */
  drm_sched_start_timeout(sched);
  

  }

Got it.

Reviewed-by: Andrey Grodzovsky andrey.grodzovsky@amd.com

Andrey

On 2022-09-09 16:30, Yadav, Arvind wrote:

On 9/9/2022 11:02 PM, Andrey Grodzovsky wrote:

...

What exactly is the scenario which this patch fixes in more detail please  ?

GPU reset issue started after adding [PATCH 6/6].

Root cause -> In drm_sched_get_cleanup_job(), We use the finished fence status bit to check the job status dma_fence_is_signaled(). If a job is signaled (DMA_FENCE_FLAG_SIGNALED_BIT is set), then we cancel the reset worker thread.

After applying [patch 6] now we are checking enable signaling in dma_fence_is_signaled() by checking DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT bit. but signaling is not enabled for the finished fence. As a result, dma_fence_is_signaled() always returns false, and drm_sched_get_cleanup_job() will not cancel the reset worker thread, resulting in the GPU reset.

To Fix the above issue  Christian suggested that we can use parent(hardware) fence instead of finished fence because signaling enabled by the calling of dma_fence_add_callback() for parent fence. As a result, dma_fence_is_signaled() will return the correct fence status and reset worker thread can be cancelled in drm_sched_get_cleanup_job().

~arvind

...

Andrey

On 2022-09-09 13:08, Arvind Yadav wrote:

...

Using the parent fence instead of the finished fence to get the job status. This change is to avoid GPU scheduler timeout error which can cause GPU reset.

Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com

changes in v1,v2 - Enable signaling for finished fence in sche_main() is removed

---

drivers/gpu/drm/scheduler/sched_main.c | 4 ++--   1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index e0ab14e0fb6b..2ac28ad11432 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -829,7 +829,7 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)       job = list_first_entry_or_null(&sched->pending_list,                          struct drm_sched_job, list);   -    if (job && dma_fence_is_signaled(&job->s_fence->finished)) { +    if (job && dma_fence_is_signaled(job->s_fence->parent)) {           /* remove job from pending_list */           list_del_init(&job->list);   @@ -841,7 +841,7 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)             if (next) {               next->s_fence->scheduled.timestamp = -                job->s_fence->finished.timestamp; +                job->s_fence->parent->timestamp;               /* start TO timer for next job */               drm_sched_start_timeout(sched);           }

Am 09.09.22 um 19:08 schrieb Arvind Yadav:

Fence signaling must be enabled to make sure that the dma_fence_is_signaled() function ever returns true. Since drivers and implementations sometimes mess this up, this ensures correct behaviour when DEBUG_WW_MUTEX_SLOWPATH is used during debugging. This should make any implementation bugs resulting in not signaled fences much more obvious.

Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com

Changes in v1,v2 : 1- Addressing Christian's comment to replace CONFIG_DEBUG_WW_MUTEX_SLOWPATH instead of CONFIG_DEBUG_FS. 2- As per Christian's comment moving this patch at last so The version of this patch is also changed and previously it was [PATCH 1/4]

---

include/linux/dma-fence.h | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 775cdc0b4f24..ba1ddc14c5d4 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -428,6 +428,11 @@ dma_fence_is_signaled_locked(struct dma_fence *fence) static inline bool dma_fence_is_signaled(struct dma_fence *fence) { +#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH

As by review comment from Tvrtko Ursulin let's add a separate config option for this into drivers/dma-buf/Kconfig

Thanks, Christian.

• if (!test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags))

• return false;
  

+#endif

• if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) return true;