From: Chris Wilson Date: Wed, 15 Nov 2017 12:14:58 +0000 (+0000) Subject: drm/i915: Clear breadcrumb node when cancelling signaling X-Git-Tag: v4.15-rc2~30^2~1^2~2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=6e068270b7883836e4717e262d96d1c43690862a;p=linux.git drm/i915: Clear breadcrumb node when cancelling signaling When we call intel_engine_cancel_signaling() to stop reporting when a request is completed via an asynchronous signal, we remove that request from the breadcrumb wait queue. However, we may be concurrently processing that request in the signaler itself, the actual operations on the request's node itself are serialised but we do not actually clear the waiter after removing it from the tree allowing both parties to attempt to do so and corrupting the rbtree. (Previously removing from the breadcrumb wait queue could only be done on behalf of i915_wait_request, so this race could not happen). Reported-by: "He, Bo" Fixes: 9eb143bbec7d ("drm/i915: Allow a request to be cancelled") Signed-off-by: Chris Wilson Cc: "He, Bo" Cc: Tvrtko Ursulin Cc: Michał Winiarski Cc: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20171115121458.24655-1-chris@chris-wilson.co.uk Reviewed-by: Joonas Lahtinen (cherry picked from commit c534612e780c4a2c8ef5bfc11583c7d58436baca) Signed-off-by: Jani Nikula --- diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c index 48e1ba01ccf8..5f8b9f1f40f1 100644 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -517,6 +517,7 @@ static void __intel_engine_remove_wait(struct intel_engine_cs *engine, GEM_BUG_ON(RB_EMPTY_NODE(&wait->node)); rb_erase(&wait->node, &b->waiters); + RB_CLEAR_NODE(&wait->node); out: GEM_BUG_ON(b->irq_wait == wait);