From nobody Fri Feb 13 07:54:19 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6DC6E82CB1 for ; Wed, 27 Sep 2023 16:55:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229522AbjI0Qzf (ORCPT ); Wed, 27 Sep 2023 12:55:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229473AbjI0Qzd (ORCPT ); Wed, 27 Sep 2023 12:55:33 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C75391 for ; Wed, 27 Sep 2023 09:55:31 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id d9443c01a7336-1c60778a3bfso73454315ad.1 for ; Wed, 27 Sep 2023 09:55:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1695833730; x=1696438530; darn=vger.kernel.org; h=message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=4l9UDvCbv8erE71IF5bB14OddV2GDc72p6otw4VVCo8=; b=EfRIJhO9aa7+sojALJ1siRldzm0R/BH51LRXo8aFc7Tzxmf6mPNq5DQ/2GvajhVS8v DPOSlPv5o3uM/n7l5OE/FLKSGpJyyCBLCoJBoGaVs+YyHG2WnL4c64f8pHPrXo8kglAj FKn+r1hhXFxWF41iYjVqZODqBRtlhDZvNIlM9gR+CjKQahpHqyQ7UVAVOu0JaiIsPKa6 +u/crPQyl6pZfDhObYCElsvj/pHdG/p+iyxaZsJukhOTXFRElSJINGwUndFSCctrV5Lo Me9nLS3wnea+rUNhqQ3Aqb9ryi8F/lI0LVJhQ4l5IRNSaL8+c5zf1EMVnleCjHiotWqa xUKw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695833730; x=1696438530; h=message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=4l9UDvCbv8erE71IF5bB14OddV2GDc72p6otw4VVCo8=; b=iS8loIk1KAMQtD98c1jPMl1RRQR/wTNb0dkNzize8jTdbkMU3jhICWWv6wifC+twpE as7hduOnJALpiGyx3KuSu58jXSyVMDuMDqqxJM7kf2Q9mdMS+RgaUvf11JEWoZ16JmwN DpwZYboRmDEZr7MlXTqdUiB+8j3dJLgRzOpNsV0sUlthHQx/+4yTgK2vv3DBoQxcdePU JZroHDgQXTO+KQUiABB9zVN1XRrCdZkljt+FxdolPqbtDatkWSIDEfvEvOISqtNJbjVD nrCoNaoPRh7VcqMmJ//QTDaUyWC8fYWi0fqqtdRQHYA8M8XOXmErS6Dzv8323brt52YG x8xQ== X-Gm-Message-State: AOJu0YzH3/gBlYUptIqbSc5N9Pn2NvCjjlP/8COzSNgAwhZdT0JYhmOC PdhU/xQ7fDfMStyQ/q2o/+ti5o+ZQ2dk/g== X-Google-Smtp-Source: AGHT+IGWIL8MNB2aNny7VvLXmLZnLXuGexINxd6mcLllIv9ZwN5xF64TeTVfNog1WEGt/rSPD7LLjA== X-Received: by 2002:a17:902:b58c:b0:1b9:e241:ad26 with SMTP id a12-20020a170902b58c00b001b9e241ad26mr2096808pls.9.1695833730513; Wed, 27 Sep 2023 09:55:30 -0700 (PDT) Received: from 377044c6c369.cse.ust.hk (191host097.mobilenet.cse.ust.hk. [143.89.191.97]) by smtp.gmail.com with ESMTPSA id e10-20020a170902744a00b001c61e628e98sm6267704plt.175.2023.09.27.09.55.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Sep 2023 09:55:29 -0700 (PDT) From: Chengfeng Ye To: kherbst@redhat.com, lyude@redhat.com, airlied@gmail.com, daniel@ffwll.ch, bskeggs@redhat.com Cc: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, Chengfeng Ye Subject: [PATCH] drm/nouveau/flcn/msgq: fix potential deadlock on &msgq->lock Date: Wed, 27 Sep 2023 16:55:17 +0000 Message-Id: <20230927165517.45066-1-dg573847474@gmail.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" As &msgq->lock is acquired under both irq context from gp102_sec2_intr() and softirq context from gm20b_pmu_recv(), thus irq should be disabled while acquiring that lock, otherwise there would be potential deadlock. gm20b_pmu_recv() --> nvkm_falcon_msgq_recv() --> nvkm_falcon_msgq_open() --> spin_lock(&msgq->lock) --> gp102_sec2_intr() --> nvkm_falcon_msgq_recv() --> nvkm_falcon_msgq_open() --> spin_lock(&msgq->lock) This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock. To prevent the potential problem, I change to spin_lock_irq() and spin_unlock_irq() on the lock. Signed-off-by: Chengfeng Ye --- drivers/gpu/drm/nouveau/nvkm/falcon/msgq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nvkm/falcon/msgq.c b/drivers/gpu/drm/n= ouveau/nvkm/falcon/msgq.c index 16b246fda666..5c3b43216ee8 100644 --- a/drivers/gpu/drm/nouveau/nvkm/falcon/msgq.c +++ b/drivers/gpu/drm/nouveau/nvkm/falcon/msgq.c @@ -25,7 +25,7 @@ static void nvkm_falcon_msgq_open(struct nvkm_falcon_msgq *msgq) { - spin_lock(&msgq->lock); + spin_lock_irq(&msgq->lock); msgq->position =3D nvkm_falcon_rd32(msgq->qmgr->falcon, msgq->tail_reg); } =20 @@ -37,7 +37,7 @@ nvkm_falcon_msgq_close(struct nvkm_falcon_msgq *msgq, boo= l commit) if (commit) nvkm_falcon_wr32(falcon, msgq->tail_reg, msgq->position); =20 - spin_unlock(&msgq->lock); + spin_unlock_irq(&msgq->lock); } =20 bool --=20 2.17.1