drm/amdgpu: revert "partial revert "remove ctx->lock" v2"

This reverts commit 94f4c4965e5513ba624488f4b601d6b385635aec.

We found that the bo_list is missing a protection for its list entries.
Since that is fixed now this workaround can be removed again.

Signed-off-by: Christian König <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 		goto free_chunk;
 	}
 
-	mutex_lock(&p->ctx->lock);
-
 	/* skip guilty context job */
 	if (atomic_read(&p->ctx->guilty) == 1) {
 		ret = -ECANCELED;
···
 	dma_fence_put(parser->fence);
 
 	if (parser->ctx) {
-		mutex_unlock(&parser->ctx->lock);
 		amdgpu_ctx_put(parser->ctx);
 	}
 	if (parser->bo_list)
···
 {
 	int i, r;
 
-	/* TODO: Investigate why we still need the context lock */
-	mutex_unlock(&p->ctx->lock);
-
 	for (i = 0; i < p->nchunks; ++i) {
 		struct amdgpu_cs_chunk *chunk;
 
···
 		case AMDGPU_CHUNK_ID_SCHEDULED_DEPENDENCIES:
 			r = amdgpu_cs_process_fence_dep(p, chunk);
 			if (r)
-				goto out;
+				return r;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_IN:
 			r = amdgpu_cs_process_syncobj_in_dep(p, chunk);
 			if (r)
-				goto out;
+				return r;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_OUT:
 			r = amdgpu_cs_process_syncobj_out_dep(p, chunk);
 			if (r)
-				goto out;
+				return r;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_TIMELINE_WAIT:
 			r = amdgpu_cs_process_syncobj_timeline_in_dep(p, chunk);
 			if (r)
-				goto out;
+				return r;
 			break;
 		case AMDGPU_CHUNK_ID_SYNCOBJ_TIMELINE_SIGNAL:
 			r = amdgpu_cs_process_syncobj_timeline_out_dep(p, chunk);
 			if (r)
-				goto out;
+				return r;
 			break;
 		}
 	}
 
-out:
-	mutex_lock(&p->ctx->lock);
-	return r;
+	return 0;
 }
 
 static void amdgpu_cs_post_dependencies(struct amdgpu_cs_parser *p)
···
 		goto out;
 
 	r = amdgpu_cs_submit(&parser, cs);
-
 out:
 	amdgpu_cs_parser_fini(&parser, r, reserved_buffers);
 

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

···
 	kref_init(&ctx->refcount);
 	ctx->mgr = mgr;
 	spin_lock_init(&ctx->ring_lock);
-	mutex_init(&ctx->lock);
 
 	ctx->reset_counter = atomic_read(&mgr->adev->gpu_reset_counter);
 	ctx->reset_counter_query = ctx->reset_counter;
···
 		drm_dev_exit(idx);
 	}
 
-	mutex_destroy(&ctx->lock);
 	kfree(ctx);
 }
 

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

···
 	bool				preamble_presented;
 	int32_t				init_priority;
 	int32_t				override_priority;
-	struct mutex			lock;
 	atomic_t			guilty;
 	unsigned long			ras_counter_ce;
 	unsigned long			ras_counter_ue;