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 E90D9D5CC8F for ; Tue, 16 Dec 2025 09:22:44 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7760B10E82F; Tue, 16 Dec 2025 09:22:44 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=lankhorst.se header.i=@lankhorst.se header.b="Tdr7Pr7B"; dkim-atps=neutral Received: from lankhorst.se (lankhorst.se [141.105.120.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id B7AC610E7C4; Tue, 16 Dec 2025 09:22:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lankhorst.se; s=default; t=1765876962; bh=LA3hIjGi9cA+PnG6A3TfKFJX6Y7TpnsugvkmMDZPIGM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Tdr7Pr7B2yYL8ddgTyt3lMphnAYWqa2GSgMecCVbOadPOqtcTtLl5Ilc9REScgWyh hHFgkx5YJYvC54fzqPzHlodpJvIzlFt7UdRSoylBV3snRt9WxlQsaxIcEVVwN0v6pn vBU/ED1ntgVt4gXVd4HGqy1ea7kWp41QmI/PbavopsDHflKuAH4wBfrSoa4dmgn84c btmabBuC7KUOAx+1Sk80QWtJrWX7cuJ+6KJcNHr17WrJ926QgKPnR1fyMX8sr3S/Pj iFRsfK9VqtfyGr9/audTMZwaZNO3ioNB94GNETkK4ArOzcUR5FxXA0m9CjDZ+38phB LpSthAbNT9MjA== From: Maarten Lankhorst To: intel-xe@lists.freedesktop.org Cc: intel-gfx@lists.freedesktop.org Subject: [i915-rt v2 15/16] drm/i915/guc: Consider also RCU depth in busy loop. Date: Tue, 16 Dec 2025 10:22:42 +0100 Message-ID: <20251216092226.1777909-33-dev@lankhorst.se> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251216092226.1777909-18-dev@lankhorst.se> References: <20251216092226.1777909-18-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