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Commit e45d7b7f authored by Changbin Du's avatar Changbin Du Committed by Zhenyu Wang
Browse files

drm/i915/gvt: fix nested sleeping issue 



We cannot use blocking method mutex_lock inside a wait loop.
Here we invoke pick_next_workload() which needs acquire a
mutex in our "condition" experssion. Then we go into a another
of the going-to-sleep sequence and changing the task state.
This is a dangerous. Let's rewrite the wait sequence to avoid
nested sleeping.

v2: fix do...while loop exit condition (zhenyu)
v3: rebase to gvt-staging branch

Signed-off-by: default avatarDu, Changbin <changbin.du@intel.com>
Signed-off-by: default avatarZhenyu Wang <zhenyuw@linux.intel.com>
parent 6fb5082a

drivers/gpu/drm/i915/gvt/scheduler.c

+12 −7
Original line number Diff line number Diff line
@@ -402,19 +402,24 @@ static int workload_thread(void *priv) 
	struct intel_vgpu_workload *workload = NULL;

	int ret;

	bool need_force_wake = IS_SKYLAKE(gvt->dev_priv);

	DEFINE_WAIT_FUNC(wait, woken_wake_function);



	kfree(p);



	gvt_dbg_core("workload thread for ring %d started\n", ring_id);



	while (!kthread_should_stop()) {

		ret = wait_event_interruptible(scheduler->waitq[ring_id],

				kthread_should_stop() ||

				(workload = pick_next_workload(gvt, ring_id)));



		WARN_ON_ONCE(ret);

		add_wait_queue(&scheduler->waitq[ring_id], &wait);

		do {

			workload = pick_next_workload(gvt, ring_id);

			if (workload)

				break;

			wait_woken(&wait, TASK_INTERRUPTIBLE,

				   MAX_SCHEDULE_TIMEOUT);

		} while (!kthread_should_stop());

		remove_wait_queue(&scheduler->waitq[ring_id], &wait);



		if (kthread_should_stop())

		if (!workload)

			break;



		mutex_lock(&scheduler_mutex);