From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 85BD9366048; Sun, 13 Sep 2026 17:47:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789321635; cv=none; b=b8lBmZtijo0KkDSCZke5klNhquVJ3O2FFpbVhRWzNcKWCga9C9kYkcCmdE2UQRY67Q5GP7vjzRGBO3Nb03a8RsrUyZLrNloThGdkZxZKmLtr+QHGR3dKW/OuI5DCf6QXX/pTWgxCDiTchQL+EsJfFgmv8neMS4Myrh5CUPdIu7M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789321635; c=relaxed/simple; bh=bZ3cbZcKzka8OzsUYfvOtU7Gwk+7yvshVdUbjo3IBOA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gZERO+nrMAzkacmA+BPi0cslspNA8mtcZowGxsTHwoD9/Uaut0dtILQKsygNZhWZbw0C69Y+L9QIn4CRxaoJhMzeQYj0b9Ii4BbTqf3+jZYq+a4DjMFkbt3B3xyXdY1Ffj5s6FnGXIOUUbuTBkOhjiFEjbeTaBbXREK2TJq4VnQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LCMUyw2A; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LCMUyw2A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 611C61F000FF; Sun, 13 Sep 2026 17:47:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789321633; bh=A2lVv0GUlGMVjlMaL7oDZcT85SbrHukw05wksytmVWk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=LCMUyw2Amx5KwfrsNaZBD0Xo5hQCD1beua/43mJngL+Oy+oIUycaVT/BUBu3QQCOR zBCJOnZZp7ahHbU3f9Yj5Gsaqg9cd2xlFUTES1s2IPhI086qlt9dfYrID/gi66yC3H 8nccufY5NsNw9N9KrIrFUm3jUqIjD3Yppo9JfD9Elkq6zW14iS/qmjkSzfLY8P/Hmy o9FxWkh/t2NXJs/KclpeSRz7n0p7ad4k3qL6PPud/nUg8zKBSq/Yeo7MMseq5ZYodw 7fsA2/vQOjMxNbKI5qYeDfqQBI6UXwwV8V3U70xhAEG184wbwJavqmRVAhVFnKvDlK SBqlQXV+R+7kQ== Message-ID: Date: Sun, 13 Sep 2026 19:47:08 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH net] mptcp: return sk_wait_data() errors from recvmsg() Content-Language: fr To: markdamirkan@gmail.com, Mat Martineau , mptcp@lists.linux.dev Cc: Jakub Kicinski , Geliang Tang , "David S. Miller" , Simon Horman , linux-kernel@vger.kernel.org, Paolo Abeni , netdev@vger.kernel.org, Eric Dumazet References: <20260913-b4-send-mptcp-recv-error-v1-1-4eaa3684a8b8@gmail.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== Organization: NGI0 Core In-Reply-To: <20260913-b4-send-mptcp-recv-error-v1-1-4eaa3684a8b8@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Mark, On 13/09/2026 12:30, Mark Amirkan via B4 Relay wrote: > From: Mark Amirkan > > Commit 581302298524 ("mptcp: error out earlier on disconnect") made > mptcp_recvmsg() stop when sk_wait_data() returns an error. The error is > stored in err, but the function then jumps to a path which returns > copied. When no data was copied, recvmsg() therefore returns zero and > reports a false EOF. > > Store the result in copied, which is the value returned by the function. > This also keeps the usual partial-read result when data was copied before > the error. Good catch! Indeed, it looks like it is a typo and "copied" was supposed to be assigned. Reviewed-by: Matthieu Baerts (NGI0) @Net maintainers: can you please apply it directly in the net tree? (if no issues are spot by Clashiko) No need to take a detour via the MPTCP tree for this fix. > A recvmsg() blocked in one thread reproduces the issue when another > thread disconnects the same MPTCP socket with connect(AF_UNSPEC). > Before this change recvmsg() returns zero; afterwards it returns -EPIPE. I see that our test suite currently doesn't exercise this error path. By chance, do you have a reproducer to avoid similar regressions later on? Ideally, one using Packetdrill, the MPTCP fork in this case [1]. [1] https://github.com/multipath-tcp/packetdrill Cheers, Matt -- Sponsored by the NGI0 Core fund.