From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (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 710CE171B0 for ; Fri, 14 Jun 2024 14:29:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=150.107.74.76 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718375356; cv=none; b=fcKuoTXSvPpYLFE8786dY+U4/4bTx/zsBMoFgAYpQOe5ebD1QrLd438ICKE4mTvLGEcGpOCCW1NBjpYTu84A7V2Vgc2gWgxm4le2aT3n0Rj9L0egPoIPpOHnentsCPYailt4J19d7JXKGKbtDiGjsjZiFwMXKlvT2OkmM1+BksA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718375356; c=relaxed/simple; bh=EjE/CNY3MYU3DSnFNB2OK5RyKukqn3rd7siASMEgtIw=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=tTQQ8xuQ7LRRAxko0zeaEaYBNPA04V/ZFB4zLznkcIC9JpK638FuwAxj/u67iMSVMFRvEKvYsjhH8g88l0FHMRh+sYQjvBsMX7g5+tjb3I5+jjhAmGVWOWCLjja15rOhWo6ZjIvHAPJF881ui9nFKKHlvQfC3nNftfAf1arQ03o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au; spf=pass smtp.mailfrom=ellerman.id.au; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b=jpyHQFNZ; arc=none smtp.client-ip=150.107.74.76 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="jpyHQFNZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1718375350; bh=C2t/dWnqkr6UGY0jC6xomHjUuYK1g2JgKYbXOiIcnKY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=jpyHQFNZnMu/eY+gCu76ejJwEq4zNXaS+/w188+Tul9GeAyP0ySGG1yf+PMWZ9V6Z ujK2EHqHUyqMi4TZD7d5JP3DcLiX8pbwttWIx44M5P9Rlu3n6miqvJA+44sWbhacFT AsaRXfqsN2NOgnGniX+EoQT2nXY8LNNV126HFq7bEjpIakvJBDheKdD9o7iPjb8L+/ JHlDhGA2MHVPfPTqXEhvj+e1mSouk6aAvfNy808cmkvFk0jbMPKYenBfqhk7Fe6VYK flce9hIPEtQ0xPnVuu5OeZan/3YhDMFRYqZoj3x8bGV0RI/ic2rONKAhucl0RFAwic s6RJM2sfYNNTg== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4W11qn4Pbgz4wc3; Sat, 15 Jun 2024 00:29:09 +1000 (AEST) From: Michael Ellerman To: Konstantin Ryabitsev , Jan Kara Cc: Thorsten Leemhuis , "ksummit@lists.linux.dev" Subject: Re: [MAINTAINERS SUMMIT] [4/4] Discuss how to better prevent backports of commits that turn out to cause regressions In-Reply-To: <20240613-rustling-chirpy-skua-d7e6cb@meerkat> References: <20240613095917.eeplayyfvl6un56y@quack3> <20240613-rustling-chirpy-skua-d7e6cb@meerkat> Date: Sat, 15 Jun 2024 00:29:09 +1000 Message-ID: <87plsjoax6.fsf@mail.lhotse> Precedence: bulk X-Mailing-List: ksummit@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Konstantin Ryabitsev writes: > On Thu, Jun 13, 2024 at 11:59:17AM GMT, Jan Kara wrote: >> > * One cause of regressions that happen in stable trees (and not in >> > mainline) I've seen quite a few times are backports of commits with >> > Fixes: tags that were part of a patch-series and depend on earlier >> > patches from the series. The stable-team afaics has no easy way to spot >> > this, as there is no way to check "was this change part of a series". >> > Sometimes I wonder if a dedicated tag linking to the submission of a >> > patch could help -- and is something quite a few maintainers already >> > really want and add using a "Link" tag despite Linus dislike for that >> > (IIRC). >> >> FWIW I (and a few other maintainers) use 'Message-Id' tag to link to >> submission. This is still easily convertible to lore link and unlike 'Link' >> tag it is clear what this tag is about and that it is not just a link to >> related discussion or something like that. AFAIK this also addresses Linus' >> dislike because what he was complaining about is that 'Link' should be >> linking to some useful context for the changelog, not just patch >> submission. > > I am strongly in favour of that from the tooling perspective. Linus suggested > that we can always trace the original patch submission from the commit by > using the patch-id, but that doesn't work reliably. I mused on that here: > > https://lore.kernel.org/git/20240605-hilarious-dramatic-mushroom-7fd941@lemur/ > > The gist is that we cannot reliably match the patch-id of the original > submission from the git commit, because there are multiple ways to generate > the same patch, such as changing the diff algorithm (myers vs. minimal vs. > histogram), or changing the number of context lines. If the original author > generated their patch with --histogram, but we try to find it by generating > the same patch using the default myers algorithm, we may not find it. > > The "Message-Id" trailer is already documented in git: > https://www.git-scm.com/docs/git-am#Documentation/git-am.txt---message-id > > I suggest we move away from the practice of using Link: trailers to indicate > the patch provenance to using Message-Id: trailers for the same purpose. This > solves multiple problems: > > 1. disambiguates Link: trailers so they point to relevant online discussions > 2. allows tooling like b4, patchwork, etc, to reliably match commits to > submissions for the purposes of better code review automation > 3. allows stable and similar projects to better track series grouping for > commits Message-Id: sucks, I want a link I can open with a single click. At your suggestion I switched to using https://msgid.link/ as the target for patch links, eg: Link: https://msgid.link/20240529123029.146953-2-mpe@ellerman.id.au Which gives the reader a hint that the link is just to the submission. I don't really care if the tag is "Link:", but it has to be a URL, not just a bare message-id that I have to cut and paste like it's the stone age. cheers