From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 72D8FCDB47F for ; Mon, 22 Jun 2026 18:10:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D58E510E803; Mon, 22 Jun 2026 18:10:47 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=lankhorst.se header.i=@lankhorst.se header.b="bkH+0MHx"; dkim-atps=neutral Received: from lankhorst.se (unknown [141.105.120.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 61FD310E803; Mon, 22 Jun 2026 18:10:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lankhorst.se; s=default; t=1782151843; bh=Q8sFpW0LaWK/Smzuxt/7dTEculaPVCfQO31xaLLhI2w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bkH+0MHx03XiLhXQNGKpyKIlqkwIUaPiOGRSrLVd9Su6FVqDG1RttTT1IuCQJ3LUS 6n5FmdrQzoM0lopO9ezNcQMGKJkCSUOgqW6oytE2QumIGzXFnLY7tHOwfIlfAK5z0I 8IDnXLkWVKSWgEVwQEMuVMgljG13v7zjVwNVNmouSliI6rX6mAQRoGIg3qplz8fVgk Jd46pI0y1fDBjbF6LluLqkCXfeDn8whj7n7/zWb8qc/yXojoxAv69JaEDLVGRAianP rqB0Jb4n5bQGhGQUcX62Jy3un5osmAKrJX+tHq/Qv9s+/XT/fyDFLODrYcHMFgNpNh p8C/1jus1w3rw== From: Maarten Lankhorst To: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Sebastian Andrzej Siewior , Clark Williams , Maarten Lankhorst , Maarten Lankhorst Subject: [PATCH v9 15/30] drm/i915/gt: Use spin_lock_irq() instead of local_irq_disable() + spin_lock() Date: Mon, 22 Jun 2026 20:10:28 +0200 Message-ID: <20260622181044.39335-16-dev@lankhorst.se> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260622181044.39335-1-dev@lankhorst.se> References: <20260622181044.39335-1-dev@lankhorst.se> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Sebastian Andrzej Siewior execlists_dequeue() is invoked from a function which uses local_irq_disable() to disable interrupts so the spin_lock() behaves like spin_lock_irq(). This breaks PREEMPT_RT because local_irq_disable() + spin_lock() is not the same as spin_lock_irq(). execlists_dequeue_irq() and execlists_dequeue() has each one caller only. If intel_engine_cs::active::lock is acquired and released with the _irq suffix then it behaves almost as if execlists_dequeue() would be invoked with disabled interrupts. The difference is the last part of the function which is then invoked with enabled interrupts. I can't tell if this makes a difference. From looking at it, it might work to move the last unlock at the end of the function as I didn't find anything that would acquire the lock again. Reported-by: Clark Williams Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Maarten Lankhorst Signed-off-by: Maarten Lankhorst --- .../drm/i915/gt/intel_execlists_submission.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c index 1359fc9cb88ef..e11db81dca9c5 100644 --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c @@ -1300,7 +1300,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) * and context switches) submission. */ - spin_lock(&sched_engine->lock); + spin_lock_irq(&sched_engine->lock); /* * If the queue is higher priority than the last @@ -1400,7 +1400,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) * Even if ELSP[1] is occupied and not worthy * of timeslices, our queue might be. */ - spin_unlock(&sched_engine->lock); + spin_unlock_irq(&sched_engine->lock); return; } } @@ -1426,7 +1426,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) if (last && !can_merge_rq(last, rq)) { spin_unlock(&ve->base.sched_engine->lock); - spin_unlock(&engine->sched_engine->lock); + spin_unlock_irq(&engine->sched_engine->lock); return; /* leave this for another sibling */ } @@ -1588,7 +1588,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine) */ sched_engine->queue_priority_hint = queue_prio(sched_engine); i915_sched_engine_reset_on_empty(sched_engine); - spin_unlock(&sched_engine->lock); + spin_unlock_irq(&sched_engine->lock); /* * We can skip poking the HW if we ended up with exactly the same set @@ -1614,13 +1614,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine) } } -static void execlists_dequeue_irq(struct intel_engine_cs *engine) -{ - local_irq_disable(); /* Suspend interrupts across request submission */ - execlists_dequeue(engine); - local_irq_enable(); /* flush irq_work (e.g. breadcrumb enabling) */ -} - static void clear_ports(struct i915_request **ports, int count) { memset_p((void **)ports, NULL, count); @@ -2475,7 +2468,7 @@ static void execlists_submission_tasklet(struct tasklet_struct *t) } if (!engine->execlists.pending[0]) { - execlists_dequeue_irq(engine); + execlists_dequeue(engine); start_timeslice(engine); } -- 2.53.0