From 82126e596d8519baac416aee83cad938f1d23cf8 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 3 Mar 2020 14:00:09 +0000 Subject: [PATCH] drm/i915/gt: Drop the timeline->mutex as we wait for retirement As we have pinned the timeline (using tl->active_count), we can safely drop the tl->mutex as we wait for what we believe to be the final request on that timeline. This is useful for ensuring that we do not block the engine heartbeat by hogging the kernel_context's timeline on a dead GPU. References: https://gitlab.freedesktop.org/drm/intel/issues/1364 Fixes: 058179e72e09 ("drm/i915/gt: Replace hangcheck by heartbeats") Fixes: f33a8a51602c ("drm/i915: Merge wait_for_timelines with retire_request") Signed-off-by: Chris Wilson Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20200303140009.1494819-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gt/intel_gt_requests.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.c index 8a5054f..24c99d0 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c +++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c @@ -147,24 +147,32 @@ long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout) fence = i915_active_fence_get(&tl->last_request); if (fence) { + mutex_unlock(&tl->mutex); + timeout = dma_fence_wait_timeout(fence, interruptible, timeout); dma_fence_put(fence); + + /* Retirement is best effort */ + if (!mutex_trylock(&tl->mutex)) { + active_count++; + goto out_active; + } } } if (!retire_requests(tl) || flush_submission(gt)) active_count++; + mutex_unlock(&tl->mutex); - spin_lock(&timelines->lock); +out_active: spin_lock(&timelines->lock); - /* Resume iteration after dropping lock */ + /* Resume list iteration after reacquiring spinlock */ list_safe_reset_next(tl, tn, link); if (atomic_dec_and_test(&tl->active_count)) list_del(&tl->link); - mutex_unlock(&tl->mutex); /* Defer the final release to after the spinlock */ if (refcount_dec_and_test(&tl->kref.refcount)) { -- 2.7.4