From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) (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 0A52614AA0; Fri, 5 Jul 2024 15:17:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720192648; cv=none; b=UF5w5QjsOTSTNQQbTxDgtjRtUFzejx5ObcePOl0i3r2rzOCwe4uLelaVp4BKetjvV2cDshiHwpgqLv1IZOeChZ1dhMCDt1HipAJl/KdBRX+ukaehl0fT6G84VKL54QcbA4AhLJHLue9GOI0CSXRZMB2HNxuTHr1KWtJQoQPa8Dk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720192648; c=relaxed/simple; bh=RFnFLxpFbGDtT10Dk/Tdh98X48tsX08DjcEQXQCwsG8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=E+1VNYPSJMTNvnz/f+TS+mpnMW8qXAIGWNk/JFO62z/nC5qNwhQzqyou2ebOVJMUhy74a5pG7eTIHi875yf2aL1XSMP/p0s0quQA+apX6Ooh2Dk3lv/whOn5sWkznJU+njjiWHEBLlrpM6t+W+BCAcw8PBdPxS3Kb3q3IAi2EjM= 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=htes5xZh; arc=none smtp.client-ip=209.85.214.176 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="htes5xZh" Received: by mail-pl1-f176.google.com with SMTP id d9443c01a7336-1fa9f540f45so11080785ad.1; Fri, 05 Jul 2024 08:17:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1720192646; x=1720797446; 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=htes5xZh8VNE+xY5+SscRBp32MDzd1w/a/jVWwYxLZm6oz8Ig8sLC9iGYHnbfX83by iaxXtkXoxWASR2jkEvWu2FYV4J6cEZosrpKZ11cJ8Hl5m8qewZP8FpFFUVRaBavoqNd9 EH+48LPZ2E1/BA9YUPHrU9OWBjRWNPXCCEFjyt3FZxMiJA4hZqetpbd9rcxJRXCaRa+w Bog2l6aMKzViOb5paDfB93+w1tB0DvxvqbpKYWPtIZL8W+BeTFCNdLEn9tYYsvgEaLU2 7VoLsTgW//rm4Ov6213XvGRgKTiDvqsp6ko37uUnsWIGnZWxEEQcLoaMC37wafGlTxgR qQ9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720192646; x=1720797446; 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=lDTAvrpa4Eo3eZ+kVF5KGVs3V1jV0NgTmf7kpUUfloqcISSQMLOiByA7YCZd+ry6th IKaXYXUI9YZ8qel0TOexlr7Xtd40w13LPRpaEpCdnpuVD/MufWxJjm14rA/dqV+rxMAP p6axTkVLG9Db5avbju1+XSulwaNeggCq/oQjzC7tuoOA7DYkAaw9Us1GjOaCAP0pYdgy QAzwMozbEUZ0VkLbm2FyXxepvq4DpywJPLZryhSfqVRzQQjpoEpO2F79l5z/28zZU0VH Xcj0qsW4IgeSh9fmtJKBV78bO+zEGD1RI7EP8S0IMcaLubgDJJ50XDmocLuCAU8VESly hAOQ== X-Forwarded-Encrypted: i=1; AJvYcCWbSN2BvCNZ/y85DCcI47kplgNcKhRXZGsvpR3U7cFE/Sdm2QvnaHBYYl9kdazr+PsLO2ysaJxeFa8vIWfuxFSngIKTWq6XlMVj22XXBRU8IEgy72vdapPX0KvHPoA1f2QVS270 X-Gm-Message-State: AOJu0Yz8m9fp2Y3y0ixv79F2CfeurhgrGbL8iWnW4T/jHDmjRzYJGhEo SNzR7WrhbwBsfy0FXjDUZmmV4jYAqeHfOGN/GscGG42EcgMKP9qq X-Google-Smtp-Source: AGHT+IHmv3SnKy6Cb7LE6Yl54nI+nlP3nioCJboV1xyLRkn6pPGtG7vxfxO0L6WHLCgUBeCqZemDNA== X-Received: by 2002:a17:902:d48f:b0:1fb:5d6f:8ce8 with SMTP id d9443c01a7336-1fb5d6f91e4mr4478835ad.52.1720192646179; Fri, 05 Jul 2024 08:17:26 -0700 (PDT) Received: from kernelexploit-virtual-machine.localdomain ([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fb5e284269sm1043535ad.187.2024.07.05.08.17.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jul 2024 08:17:25 -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: [syzbot] [net?] possible deadlock in team_del_slave (3) Date: Sat, 6 Jul 2024 00:17:19 +0900 Message-Id: <20240705151719.94431-1-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); --