[PATCH 4.4 187/342] drm/amdgpu: hold reference to fences in amdgpu_sa_bo_new (v2)
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-03-02 00:50:45
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4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicolai Hähnle <redacted> commit a8d81b36267366603771431747438d18f32ae2d5 upstream. 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: Nicolai Hähnle <redacted> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sa.c@@ -354,12 +354,15 @@ int amdgpu_sa_bo_new(struct amdgpu_sa_ma 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 {