From 8a5746982e0fdabae85990d90a9b80e107fcd450 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 28 Jan 2020 17:16:14 +0000 Subject: [PATCH] drm/i915/execlist: Mark up racy read of execlists->pending[0] We write to execlists->pending[0] in process_csb() to acknowledge the completion of the ESLP update, outside of the main spinlock. When we check the current status of the previous submission in __execlists_submission_tasklet() we should therefore use READ_ONCE() to reflect and document the unsynchronized read. Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20200128171614.3845825-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gt/intel_lrc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index f1ea2138cbba..677efdc7c301 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -2347,7 +2347,7 @@ static void process_csb(struct intel_engine_cs *engine) static void __execlists_submission_tasklet(struct intel_engine_cs *const engine) { lockdep_assert_held(&engine->active.lock); - if (!engine->execlists.pending[0]) { + if (!READ_ONCE(engine->execlists.pending[0])) { rcu_read_lock(); /* protect peeking at execlists->active */ execlists_dequeue(engine); rcu_read_unlock(); -- GitLab