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Commit a8d81b36 authored by Nicolai Hähnle's avatar Nicolai Hähnle Committed by Alex Deucher
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drm/amdgpu: hold reference to fences in amdgpu_sa_bo_new (v2) 



An arbitrary amount of time can pass between spin_unlock and
fence_wait_any_timeout, so we need to ensure that nobody frees the
fences from under us.

A stress test (rapidly starting and killing hundreds of glxgears
instances) ran into a deadlock in fence_wait_any_timeout after
about an hour, and this race condition appears to be a plausible
cause.

v2: agd: rebase on upstream

Signed-off-by: default avatarNicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org
parent ca198528

drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c

+4 −1
Original line number Diff line number Diff line
@@ -354,12 +354,15 @@ int amdgpu_sa_bo_new(struct amdgpu_sa_manager *sa_manager, 


		for (i = 0, count = 0; i < AMDGPU_MAX_RINGS; ++i)

			if (fences[i])

				fences[count++] = fences[i];

				fences[count++] = fence_get(fences[i]);



		if (count) {

			spin_unlock(&sa_manager->wq.lock);

			t = fence_wait_any_timeout(fences, count, false,

						   MAX_SCHEDULE_TIMEOUT);

			for (i = 0; i < count; ++i)

				fence_put(fences[i]);



			r = (t > 0) ? 0 : t;

			spin_lock(&sa_manager->wq.lock);

		} else {