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 35284D6E2B4 for ; Thu, 18 Dec 2025 16:34:05 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B213310EA81; Thu, 18 Dec 2025 16:34:04 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=lankhorst.se header.i=@lankhorst.se header.b="MnzGvd9o"; dkim-atps=neutral Received: from lankhorst.se (lankhorst.se [141.105.120.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4FC8B10EA73; Thu, 18 Dec 2025 16:33:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lankhorst.se; s=default; t=1766075634; bh=LA3hIjGi9cA+PnG6A3TfKFJX6Y7TpnsugvkmMDZPIGM=; h=From:To:Subject:Date:In-Reply-To:References:From; b=MnzGvd9oMgoChIn993OwJdpVdoZ/uPtFJrb8j9p5vlGwKP4vH03iEBhbMAy4AXWrp AP+z/edD9LEV54i+JpSBmpyejrzRzQYyoqCSuy6wTCXZwrFL3TMwrJumBVO1A0dz37 94C3L584elGVPiNoRVT+Sq7oenuHWxx0cEXKdFT9v0ThO63cweKCSb1zWdpdHBZzXh eb2irCCVnVTAeGs0B+5rhEMIAnCQmLJy+8e/eoiF+IGiO18FBa9WEDYUama5nXjVMk 6kcstIoNaqp9oTFstEVk7quW47RcvZ04AvQ+ZpLbC4mAFMurUah0E457vOfm/eptMZ y+iE7PvHK03aA== From: Maarten Lankhorst To: intel-xe@lists.freedesktop.org, intel-gfx@lists.freedesktop.org Subject: [i915-rt v4 15/20] drm/i915/guc: Consider also RCU depth in busy loop. Date: Thu, 18 Dec 2025 17:34:03 +0100 Message-ID: <20251218163408.97508-16-dev@lankhorst.se> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251218163408.97508-1-dev@lankhorst.se> References: <20251218163408.97508-1-dev@lankhorst.se> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" From: Sebastian Andrzej Siewior intel_guc_send_busy_loop() looks at in_atomic() and irqs_disabled() to decide if it should busy-spin while waiting or if it may sleep. Both checks will report false on PREEMPT_RT if sleeping spinlocks are acquired leading to RCU splats while the function sleeps. Check also if RCU has been disabled. Reported-by: "John B. Wyatt IV" Reviewed-by: Rodrigo Vivi Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Maarten Lankhorst --- drivers/gpu/drm/i915/gt/uc/intel_guc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 053780f562c1a..b25fa8f4dc4bd 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -362,7 +362,7 @@ static inline int intel_guc_send_busy_loop(struct intel_guc *guc, { int err; unsigned int sleep_period_ms = 1; - bool not_atomic = !in_atomic() && !irqs_disabled(); + bool not_atomic = !in_atomic() && !irqs_disabled() && !rcu_preempt_depth(); /* * FIXME: Have caller pass in if we are in an atomic context to avoid -- 2.51.0