[PATCH 04/71] drm/i915/gt: Cancel the preemption timeout on responding to it

[Chris Wilson]

We currently presume that the engine reset is successful, cancelling the
expired preemption timer in the process. However, engine resets can
fail, leaving the timeout still pending and we will then respond to the
timeout again next time the tasklet fires. What we want is for the
failed engine reset to be promoted to a full device reset, which is
kicked by the heartbeat once the engine stops processing events.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/1168
Fixes: 3a7a92aba8fb ("drm/i915/execlists: Force preemption")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: <stable at vger.kernel.org> # v5.5+
---
 drivers/gpu/drm/i915/gt/intel_lrc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 1d209a8a95e8..7f25894e41d5 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -3209,8 +3209,10 @@ static void execlists_submission_tasklet(unsigned long data)
 		spin_unlock_irqrestore(&engine->active.lock, flags);
 
 		/* Recheck after serialising with direct-submission */
-		if (unlikely(timeout && preempt_timeout(engine)))
+		if (unlikely(timeout && preempt_timeout(engine))) {
+			cancel_timer(&engine->execlists.preempt);
 			execlists_reset(engine, "preemption time out");
+		}
 	}
 }
 
-- 
2.20.1