From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E99EF2EC541; Fri, 19 Dec 2025 10:48:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766141326; cv=none; b=PfUp8feIqYgbMPyKfW16U+sTGE5z1eKabEUJWdQ+iQ+YFDN1imYSNlJQ3+t6ku7U8a9wUscowpcptMJzU9qURCfSpIqTKj77ze2K+hCY7u5AGti9+P22+JFxdscqFjXukYrBcf4hWTfRd+GdtxFryy6IImlBHcgIteezJ+roVXE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766141326; c=relaxed/simple; bh=YjLoTYKDjQc7ykxQOyqOUVAmPo1a4U7SoiPnS819chY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=laYrgEIlbJeQFqQ1Eha/tkUIMFbLwiHzevx3YTqXFCrG8f3PpSEvkibFuToFXuXjyjIPeTAxY7KPN2yjDQiq2osMO7SDMneYK96jWvHmj6yHqjEQ1nE7bfZNEVQ20Iz/AYdDX6V5Bn0gFl542enVhBC1lvIl7VCAmLki5nd72Hc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=L7bqolvB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="L7bqolvB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61349C4CEF1; Fri, 19 Dec 2025 10:48:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766141325; bh=YjLoTYKDjQc7ykxQOyqOUVAmPo1a4U7SoiPnS819chY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=L7bqolvBFOR101dxP5KRLI3a89z2sYRaD5NMDs6Ftuij/N0gZwi4QNAdCHeojZTnS sTmw64BxfL5fRcmcwE0zNkijE6ByCan7iAD/1xcIEITD9mANijFwiu6u4vqpCvBmdx rVhNGqtC3jylNs9DFq/plyoUdZN6FTZ9+Du71noT/eH0gK7qafW3x9wk2b66h1QmFU iHh8MIDUnindvn/xXUhcuigCG4S2n7szUwb9sjTlMSO4EFH89QNRR+Vpz3uEOG5TRA AIiZ2NmPwbFxNkh03fN6c4S2gDllgUQR+Es2ZssCD5m0x4BgFYlPkruIu6nqAfp3Rr aU7NU187DIl/g== Message-ID: <96b827e5-d8b7-4e0d-b5a8-1729f5177134@kernel.org> Date: Fri, 19 Dec 2025 11:48:39 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 44/44] net/mptcp: Change some dubious min_t(int, ...) to min() Content-Language: en-GB, fr-BE To: David Laight Cc: linux-kernel@vger.kernel.org, mptcp@lists.linux.dev, netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Mat Martineau , Paolo Abeni References: <20251119224140.8616-1-david.laight.linux@gmail.com> <20251119224140.8616-45-david.laight.linux@gmail.com> <20251218201517.2f2d91d4@pumpkin> 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: <20251218201517.2f2d91d4@pumpkin> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi David, Thank you for your reply! On 18/12/2025 21:15, David Laight wrote: > On Thu, 18 Dec 2025 18:33:26 +0100 > Matthieu Baerts wrote: > >> Hi David, >> >> On 19/11/2025 23:41, david.laight.linux@gmail.com wrote: >>> From: David Laight >>> >>> There are two: >>> min_t(int, xxx, mptcp_wnd_end(msk) - msk->snd_nxt); >>> Both mptcp_wnd_end(msk) and msk->snd_nxt are u64, their difference >>> (aka the window size) might be limited to 32 bits - but that isn't >>> knowable from this code. >>> So checks being added to min_t() detect the potential discard of >>> significant bits. >>> >>> Provided the 'avail_size' and return of mptcp_check_allowed_size() >>> are changed to an unsigned type (size_t matches the type the caller >>> uses) both min_t() can be changed to min(). >> >> Thank you for the patch! >> >> Reviewed-by: Matthieu Baerts (NGI0) >> >> I'm not sure what the status on your side: I don't know if you still >> plan to send a specific series for all the modifications in the net, but >> just in case, I just applied your patch in the MPTCP tree. I removed the >> "net/" prefix from the subject. I will send this patch with others for >> including in the net-next tree later on if you didn't do that in between. > > I'll go through them again at some point. Great, thank you! > I'll check against 'next' (but probably not net-next). net-next is in linux-next, so that should be fine. > I actually need to look at the ones that seemed like real bugs when I > did an allmodconfig build - that got to over 200 patches to get 'clean'. > > It would be nice to get rid of a lot of the min_t(), but I might try > to attack the dubious ones rather than the ones that appear to make > no difference. > > I might propose some extra checks in minmax.h that would break W=1 builds. > Detecting things like min_t(u8, u32_value, 0xff) where the cast makes the > comparison always succeed. > In reality any calls with casts to u8 and u16 are 'dubious'. > > That and changing checkpatch.pl to not suggest min_t() at all, and > to reject the more dubious uses. > After all with: > min(x, (int)y) > it is clear to the reader that 'y' is being possibly truncated and converted > to a signed value, but with: > min_t(int, x, y) > you don't know which value needed the cast (and the line isn't even shorter). > But what I've found all to often is actually: > a = min_t(typeof(a), x, y); > and the similar: > x = min_t(typeof(x), x, y); > where the type of the result is used and high bits get discarded. Good idea to add extra checks and prevent future issues! > I've just been trying to build with #define clamp_val clamp. > That requires a few minor changes and I'm pretty sure shows up > a real bug. Thank you for looking at that! Cheers, Matt -- Sponsored by the NGI0 Core fund.