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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 BF235C982E1 for ; Mon, 21 Sep 2026 07:24:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:References:From: To:Cc:Subject:Message-Id:Date:Content-Type:Content-Transfer-Encoding: Mime-Version:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=RG0d/rWWwG5EWi14PZmG5qQITNqAdcjhf3I0KoA9dFs=; b=b3bA/roxQuTOSH5Jcy30pCI0mU 5z8/PIItmJKATuUR/B1Ijw1ts5LDNIskSEKj9wTuOsx2bGjrYbCYLfok55yu/hgqxQFxfC2hHVCNo b3PtLqH/GCq+9xPnqOGBWowpY8twxrLi1I1Q5KbJU7vymQfSJY54VrWPKkoTpbzJZ5Ol8BiW+ucXk 9boGZD7xGwIm+hoWO1zVU+/7OytnEUfcphQEu+sl2Xtw3+t30HMsZQu/t+dI6PXWaQ1pwHQsnKzLb BUUEsYc/vrpVOtWX/UeifEN73S+Lg/da8MH1/HJHGoyngIlICYAjUAwuhDbfHn1u6VpO86OK6HrGX rlVuwmtA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8YNz-00000001CLJ-1WGB; Mon, 21 Sep 2026 07:24:23 +0000 Received: from smtpout-02.galae.net ([185.246.84.56]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8YNn-00000001CEV-1oL0 for linux-arm-kernel@lists.infradead.org; Mon, 21 Sep 2026 07:24:12 +0000 Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id C05BA1A0E7C; Mon, 21 Sep 2026 07:24:09 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 7AB9F60339; Mon, 21 Sep 2026 07:24:09 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 1BA8610328F4D; Mon, 21 Sep 2026 09:23:56 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1789975447; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=RG0d/rWWwG5EWi14PZmG5qQITNqAdcjhf3I0KoA9dFs=; b=CF4oYu2f2Fb/6/P7G2edz+XGRaxwUM5y+QalfFftYc0K9ACk3pKG19v1Um+gp+onLXLOAJ XIWebq+ZnBsUGIWQ/NZNNkbdrZLZrg9SmIbGwpb8GFep47g3S359CAIOawHvPUMBfq002u 5YsxQvNUoAdJlltQ+8pJAMoO9OeuxcUunDnEDL25IhJ6iIvH4yM+gdd0dcHzAnw7Kf6JMb wffUF0B8jCFMuYKQjMW1VJ8wgJntfoU7V5WjeW6JE1H9DxBVy0+KgqXljo4rgC0CUOy6tI vl2QvKL5UETgKy276ScNoF4LORkAjcvyc021rRxRFh4Sb/93oVLYRy/9WfDKZg== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 21 Sep 2026 09:23:55 +0200 Message-Id: Subject: Re: [PATCH v11 14/74] drm/bridge: Fix unlocked list access in drm_bridge_attach() Cc: , , , , , , To: "Cristian Ciocaltea" , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , "Dave Stevenson" , "Dmitry Baryshkov" , "Andrzej Hajda" , "Neil Armstrong" , "Robert Foss" , "Laurent Pinchart" , "Jonas Karlman" , "Jernej Skrabec" , "Luca Ceresoli" , "Chen-Yu Tsai" , "Samuel Holland" , =?utf-8?q?Ma=C3=ADra_Canal?= , "Raspberry Pi Kernel Maintenance" , "Raphael Gallais-Pou" , "Sandy Huang" , =?utf-8?q?Heiko_St=C3=BCbner?= , "Andy Yan" , "Algea Cao" , "Daniel Stone" , "Liu Ying" , "Phong LE" , "Helge Deller" From: "Luca Ceresoli" X-Mailer: aerc 0.22.0 References: <20260901-dw-hdmi-qp-scramb-v11-0-bc12954a0688@collabora.com> <20260901-dw-hdmi-qp-scramb-v11-14-bc12954a0688@collabora.com> In-Reply-To: <20260901-dw-hdmi-qp-scramb-v11-14-bc12954a0688@collabora.com> X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260921_002411_636759_B1435120 X-CRM114-Status: UNSURE ( 9.59 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue Sep 1, 2026 at 8:50 PM CEST, Cristian Ciocaltea wrote: > drm_bridge_attach() inspects bridge->list to warn about bridges being > attached without a previous drm_bridge_add() call, but it does so > without holding bridge_lock. > > The list head can be concurrently written by drm_bridge_add(), > drm_bridge_remove() and __drm_bridge_free() while they operate on > neighbouring entries of bridge_list or bridge_lingering_list, all of > them under bridge_lock. Hence the unlocked read is a data race, even > though it is unlikely to change the outcome of list_empty() in practice. > > Perform the check with bridge_lock held. > > Fixes: 76f1a9711b83 ("drm/bridge: add warning for bridges attached withou= t being added") > Signed-off-by: Cristian Ciocaltea Reviewed-by: Luca Ceresoli -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com