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drm/i915: Protect request peeking with RCU 

Since the execlists_active() is no longer protected by the
engine->active.lock, we need to protect the request pointer with RCU to
prevent it being freed as we evaluate whether or not we need to preempt.

Fixes: df40306902 ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock")
Fixes: 13ed13a4dc ("drm/i915: Don't set queue_priority_hint if we don't kick the submission")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191104090158.2959-2-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2019-11-03 16:23:05 +00:00
parent 83c55ee82f
commit 7d14863525
1 changed files with 7 additions and 2 deletions
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9
drivers/gpu/drm/i915/i915_scheduler.c
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@ -202,21 +202,26 @@ static void kick_submission(struct intel_engine_cs *engine,
if (prio <= engine->execlists.queue_priority_hint) if (prio <= engine->execlists.queue_priority_hint)
return; return;
rcu_read_lock();
/* Nothing currently active? We're overdue for a submission! */ /* Nothing currently active? We're overdue for a submission! */
inflight = execlists_active(&engine->execlists); inflight = execlists_active(&engine->execlists);
if (!inflight) if (!inflight)
return; goto unlock;
/* /*
* If we are already the currently executing context, don't * If we are already the currently executing context, don't
* bother evaluating if we should preempt ourselves. * bother evaluating if we should preempt ourselves.
*/ */
if (inflight->hw_context == rq->hw_context) if (inflight->hw_context == rq->hw_context)
return; goto unlock;
engine->execlists.queue_priority_hint = prio; engine->execlists.queue_priority_hint = prio;
if (need_preempt(prio, rq_prio(inflight))) if (need_preempt(prio, rq_prio(inflight)))
tasklet_hi_schedule(&engine->execlists.tasklet); tasklet_hi_schedule(&engine->execlists.tasklet);
unlock:
rcu_read_unlock();
} }
static void __i915_schedule(struct i915_sched_node *node, static void __i915_schedule(struct i915_sched_node *node,