drm/i915/reset: Handle reset timeouts under unrelated kernel hangs

When resuming after hibernate sometimes we see hangs in unrelated kernel
subsystems. These hangs often result in the following i915 trace:

i915 0000:00:02.0: [drm] *ERROR* \
	intel_gt_reset_global timed out, cancelling all in-flight rendering

implying our reset task has been starved by the hanging kernel subsystem,
causing us to inappropiately declare the system as wedged beyond recovery.

The trace would be caused by our synchronize_srcu_expedited() taking more
than the allowed 5s due to the unrelated kernel hang. But we neither need
to perform that synchronisation inside the reset watchdog, nor do we need
such a short timeout before declaring the device as unrecoverable.

v2: Restore watchdog timeout to the previous 5 seconds (Ashutosh)

Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/3575
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220630043959.5708-1-ashutosh.dixit@intel.com

diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
index c68d36fb5bbdd997b7c2732f459a59249273e5f2..1211774e1d91fe323fed3f4ad912050f22f28c71 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -1281,9 +1281,6 @@ static void intel_gt_reset_global(struct intel_gt *gt,
        intel_wedge_on_timeout(&w, gt, 5 * HZ) {
                intel_display_prepare_reset(gt->i915);
 
-               /* Flush everyone using a resource about to be clobbered */
-               synchronize_srcu_expedited(&gt->reset.backoff_srcu);
-
                intel_gt_reset(gt, engine_mask, reason);
 
                intel_display_finish_reset(gt->i915);
@@ -1392,6 +1389,9 @@ void intel_gt_handle_error(struct intel_gt *gt,
                }
        }
 
+       /* Flush everyone using a resource about to be clobbered */
+       synchronize_srcu_expedited(&gt->reset.backoff_srcu);
+
        intel_gt_reset_global(gt, engine_mask, msg);
 
        if (!intel_uc_uses_guc_submission(&gt->uc)) {