From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f53.google.com (mail-ot1-f53.google.com [209.85.210.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F5D91487D8; Fri, 5 Jul 2024 15:19:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720192749; cv=none; b=laA44izNH3uIda8Lnz66w5u5b1RqUb+9w3CsLBA9s8/c46Xcy3avDdluzyeL5UGiwkxs/10Jn5o1bZmd+rbXXZagsD2gQMBPFZ6SOmHvbFllQvlzLOIALu5Zdg14bc8Ie4/PWG5vOl7SZH7sb/LtsRXkEmCqR0Msc8q8sf9FWfU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720192749; c=relaxed/simple; bh=RFnFLxpFbGDtT10Dk/Tdh98X48tsX08DjcEQXQCwsG8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=dUJd5KYN1XvndxZxdqsS1ej+lenrljRsT3WhhH3w5Qag24Fitj8x+ZVUjBtCzBwXjB7AiN85YB1LjftGkLhTj1v9dVACDFKeVvgN6e+JqsIDy26S2W2dANxXhj35pMOi1VjL7qQigY69aBkkICAWqNKjc2Za2S2xVrVdNqkE0y8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=iPnn0MJm; arc=none smtp.client-ip=209.85.210.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="iPnn0MJm" Received: by mail-ot1-f53.google.com with SMTP id 46e09a7af769-702294d6265so1118505a34.1; Fri, 05 Jul 2024 08:19:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1720192747; x=1720797547; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=xfgcjToHDms+e/xA2Hsd4lyRapgO6QBy6Yt2Qi/WJcY=; b=iPnn0MJmzNKMM84I8BiQzyiFvBpR76Z1/AtVWz/Ab3wY0fPT+7xHpqpxYWXgG7cBQU /f3Y3FvXqL+5ZJpG7dLCJOXcn8XXJUCgPq8DC25bQAEm0q7PzPmsuYBI57nZse20HxgE FyWwWeG4AY+32RaiQK10bRp1KYd6GAf0lI1/irJgVe+qUURwd/HLhCddIShpMeaD6+wK Th9X+VpHDA/+Tm0joNgXt5wRi6bAh3g1CKLEMui+VD584OrX4WmPBHRuD17mj5wMwLjr 2CSzHCVoKgSf01bSwDnLzY90n8tOj5WuEJ8zLhD7rLYmK+hbqGmQYdHAl9rRy5OXFijE AObA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720192747; x=1720797547; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=xfgcjToHDms+e/xA2Hsd4lyRapgO6QBy6Yt2Qi/WJcY=; b=Ul5gkvxVdeHFgUvuvRsdcE5+haNdfG0VgjGaL1OcmAkE8Dtzmtgo4lWhAMBlWwemfG ywSBoGdPtUD2Dupr4bI4kVjCrCxdpM03zRGHD6yy/yggxpe9wvd4R4mn5kH6i5bnExke tvWWIkAy6TCJusGoSOjQG6DDbhPogQFeW7Ari8PNwX8d4IJUuaVMMOfvU5uVJ6SHp2uU O1B9Z9KCdCX1ZfS2OEbCpYv6pHU3Ouf0y1y7Uom5nQPB2sai/1hjFZCyuNHtWSX6CgRt CfUbgJvfdY1gWBzFbsWEMAIR+080zdPkp8dF54zYyc+WJqPxS7aqkWdoVd19A9k8rCDt GpsA== X-Forwarded-Encrypted: i=1; AJvYcCV1ExtXTkcTBgBkGq3xw1Kr+8+Jq5WQhrctwLIJFl80Ypr1yaT/FUjO0GMmtNRrLHYRXo6f00wtZOZ18/Wfie60f4KQ+0YATWLTf/lia6THFG2yGQU10OD6j27EZC4XhJRJ9HeI X-Gm-Message-State: AOJu0YzT8q2NBILhGB8VqTWbiHnXBVzQyuhU2h324NKVVb39cy1CNWPa zpCvC/fUS+T623G3ExmyCpEu624hXi8K1n/2Wt9kcqLx8hlSm0Vt X-Google-Smtp-Source: AGHT+IGj09BYI4AoXFXbl4HIMN5eYqJfhUFpuaRzrTu+XlgaJmIgRV2oGaVo/F6rlNg9FL3H+RKRQg== X-Received: by 2002:a05:6358:6f0f:b0:1a5:2f55:c47b with SMTP id e5c5f4694b2df-1aa98c2430emr514351355d.10.1720192746611; Fri, 05 Jul 2024 08:19:06 -0700 (PDT) Received: from kernelexploit-virtual-machine.localdomain ([121.185.186.233]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-72c6c7f72a7sm11087720a12.63.2024.07.05.08.19.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jul 2024 08:19:05 -0700 (PDT) From: Jeongjun Park To: edumazet@google.com Cc: aha310510@gmail.com, davem@davemloft.net, jiri@resnulli.us, kuba@kernel.org, linux-kernel@vger.kernel.org, michal.kubiak@intel.com, netdev@vger.kernel.org, pabeni@redhat.com, syzbot+705c61d60b091ef42c04@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH net] team: Fix ABBA deadlock caused by race in team_del_slave Date: Sat, 6 Jul 2024 00:19:00 +0900 Message-Id: <20240705151900.94546-1-aha310510@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit > > > > Thanks for your comment. I rewrote the patch based on those comments. > > This time, we modified it to return an error so that resources are not > > modified when a race situation occurs. We would appreciate your > > feedback on what this patch would be like. > > > > > Thanks, > > > Michal > > > > > > > > > > Regards, > > Jeongjun Park > > > > --- > >  drivers/net/team/team_core.c | 6 ++++-- > >  1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c > > index ab1935a4aa2c..43d7c73b25aa 100644 > > --- a/drivers/net/team/team_core.c > > +++ b/drivers/net/team/team_core.c > > @@ -1972,7 +1972,8 @@ static int team_add_slave(struct net_device *dev, struct net_device *port_dev, > >         struct team *team = netdev_priv(dev); > >         int err; > > > > -       mutex_lock(&team->lock); > > +       if (!mutex_trylock(&team->lock)) > > +               return -EBUSY; > >         err = team_port_add(team, port_dev, extack); > >         mutex_unlock(&team->lock); > > > > @@ -1987,7 +1988,8 @@ static int team_del_slave(struct net_device *dev, struct net_device *port_dev) > >         struct team *team = netdev_priv(dev); > >         int err; > > > > -       mutex_lock(&team->lock); > > +       if (!mutex_trylock(&team->lock)) > > +               return -EBUSY; > >         err = team_port_del(team, port_dev); > >         mutex_unlock(&team->lock); > > > > -- > > Failing team_del_slave() is not an option. It will add various issues. Thank you for comment. So, how about briefly releasing the lock before calling dev_open() in team_port_add() and then locking it again? dev_open() does not use &team, so disabling it briefly will not cause any major problems. Regards, Jeongjun Park --- drivers/net/team/team_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c index ab1935a4aa2c..245566a1875d 100644 --- a/drivers/net/team/team_core.c +++ b/drivers/net/team/team_core.c @@ -1213,7 +1213,9 @@ static int team_port_add(struct team *team, struct net_device *port_dev, goto err_port_enter; } + mutex_unlock(&team->lock); err = dev_open(port_dev, extack); + mutex_lock(&team->lock); if (err) { netdev_dbg(dev, "Device %s opening failed\n", portname); --