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Commit 7e9d3a4a authored by Chris Wilson's avatar Chris Wilson Committed by Joonas Lahtinen
Browse files

drm/i915: Wrap engine->schedule in RCU locks for set-wedge protection 



Similar to the staging around handling of engine->submit_request, we
need to stop adding to the execlists->queue prior to calling
engine->cancel_requests. cancel_requests will move requests from the
queue onto the timeline, so if we add a request onto the queue after that
point, it will be lost.

Fixes: af7a8ffa ("drm/i915: Use rcu instead of stop_machine in set_wedged")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180307134226.25492-5-chris@chris-wilson.co.uk


(cherry picked from commit 47650db0)
Signed-off-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
parent 84d4ebdb

drivers/gpu/drm/i915/i915_gem.c

+7 −6
Original line number Diff line number Diff line
@@ -471,10 +471,11 @@ static void __fence_set_priority(struct dma_fence *fence, int prio) 


	rq = to_request(fence);

	engine = rq->engine;

	if (!engine->schedule)

		return;



	rcu_read_lock();

	if (engine->schedule)

		engine->schedule(rq, prio);

	rcu_read_unlock();

}



static void fence_set_priority(struct dma_fence *fence, int prio)
@@ -3214,8 +3215,11 @@ void i915_gem_set_wedged(struct drm_i915_private *i915) 
	 */

	for_each_engine(engine, i915, id) {

		i915_gem_reset_prepare_engine(engine);



		engine->submit_request = nop_submit_request;

		engine->schedule = NULL;

	}

	i915->caps.scheduler = 0;



	/*

	 * Make sure no one is running the old callback before we proceed with
@@ -3233,11 +3237,8 @@ void i915_gem_set_wedged(struct drm_i915_private *i915) 
		 * start to complete all requests.

		 */

		engine->submit_request = nop_complete_submit_request;

		engine->schedule = NULL;

	}



	i915->caps.scheduler = 0;



	/*

	 * Make sure no request can slip through without getting completed by

	 * either this call here to intel_engine_init_global_seqno, or the one

drivers/gpu/drm/i915/i915_request.c

+2 −0
Original line number Diff line number Diff line
@@ -1081,8 +1081,10 @@ void __i915_request_add(struct i915_request *request, bool flush_caches) 
	 * decide whether to preempt the entire chain so that it is ready to

	 * run at the earliest possible convenience.

	 */

	rcu_read_lock();

	if (engine->schedule)

		engine->schedule(request, request->ctx->priority);

	rcu_read_unlock();



	local_bh_disable();

	i915_sw_fence_commit(&request->submit);