drm/amdgpu: check context id for context switching (v2)

check the filp is not robust, and sometimes different contexts may
have same filp value.

v2: check both filp and ctx_id
Signed-off-by: Jammy Zhou <Jammy.Zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -945,6 +945,7 @@ struct amdgpu_ring {
 	unsigned		next_rptr_offs;
 	unsigned		fence_offs;
 	struct drm_file		*current_filp;
+	unsigned		current_ctx;
 	bool			need_ctx_switch;
 	enum amdgpu_ring_type	type;
 	char			name[16];

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

@@ -642,8 +642,10 @@ static int amdgpu_cs_ib_fill(struct amdgpu_device *adev,
 			ib->is_const_ib = true;
 		if (chunk_ib->flags & AMDGPU_IB_FLAG_GDS)
 			ib->gds_needed = true;
-		if (ib->ring->current_filp != parser->filp) {
+		if ((ib->ring->current_filp != parser->filp) ||
+		    (ib->ring->current_ctx != parser->ctx_id)) {
 			ib->ring->need_ctx_switch = true;
+			ib->ring->current_ctx = parser->ctx_id;
 			ib->ring->current_filp = parser->filp;
 		}