[PATCH] drm/amdgpu: guard ib scheduling while in reset

[S, Shirish]

[Why]
Upon GPU reset, kernel cleans up already submitted jobs
via drm_sched_cleanup_jobs.
This schedules ib's via drm_sched_main()->run_job, leading to
race condition of rings being ready or not, since during reset
rings may be suspended.

[How]
make GPU reset's amdgpu_device_ip_resume_phase2() &
amdgpu_ib_schedule() in amdgpu_job_run() mutually exclusive.

Signed-off-by: Shirish S <shirish.s at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h        | 1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 3 +++
 drivers/gpu/drm/amd/amdgpu/amdgpu_job.c    | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index f4d9041..7b07a47b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -973,6 +973,7 @@ struct amdgpu_device {
 	bool                            in_gpu_reset;
 	enum pp_mp1_state               mp1_state;
 	struct mutex  lock_reset;
+	struct mutex  lock_ib_sched;
 	struct amdgpu_doorbell_index doorbell_index;
 
 	int asic_reset_res;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 676cad1..63cad74 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -2759,6 +2759,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	mutex_init(&adev->virt.vf_errors.lock);
 	hash_init(adev->mn_hash);
 	mutex_init(&adev->lock_reset);
+	mutex_init(&adev->lock_ib_sched);
 	mutex_init(&adev->virt.dpm_mutex);
 	mutex_init(&adev->psp.mutex);
 
@@ -3795,7 +3796,9 @@ static int amdgpu_do_asic_reset(struct amdgpu_hive_info *hive,
 				if (r)
 					return r;
 
+				mutex_lock(&tmp_adev->lock_ib_sched);
 				r = amdgpu_device_ip_resume_phase2(tmp_adev);
+				mutex_unlock(&tmp_adev->lock_ib_sched);
 				if (r)
 					goto out;
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
index e1bad99..cd6082d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
@@ -233,8 +233,10 @@ static struct dma_fence *amdgpu_job_run(struct drm_sched_job *sched_job)
 	if (finished->error < 0) {
 		DRM_INFO("Skip scheduling IBs!\n");
 	} else {
+		mutex_lock(&ring->adev->lock_ib_sched);
 		r = amdgpu_ib_schedule(ring, job->num_ibs, job->ibs, job,
 				       &fence);
+		mutex_unlock(&ring->adev->lock_ib_sched);
 		if (r)
 			DRM_ERROR("Error scheduling IBs (%d)\n", r);
 	}
-- 
2.7.4