[PATCH] drm/amdgpu: install ctx entities with cmpxchg

[Christian König]

Since we removed the context lock we need to make sure that not two threads
are trying to install an entity at the same time.

Signed-off-by: Christian König <christian.koenig at amd.com>
Fixes: e68efb27647f ("drm/amdgpu: remove ctx->lock")
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
index f522b52725e4..16eb1ee600ed 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
@@ -204,9 +204,15 @@ static int amdgpu_ctx_init_entity(struct amdgpu_ctx *ctx, u32 hw_ip,
 	if (r)
 		goto error_free_entity;
 
-	ctx->entities[hw_ip][ring] = entity;
+	/* It's not an error if we fail to install the new entity */
+	if (cmpxchg(&ctx->entities[hw_ip][ring], NULL, entity))
+		goto cleanup_entity;
+
 	return 0;
 
+cleanup_entity:
+	drm_sched_entity_fini(&entity->entity);
+
 error_free_entity:
 	kfree(entity);
 
-- 
2.25.1