Re: [patch] Documentation: SubmittingPatches: overhaul changelog howto

[Ingo Molnar <mingo@kernel.org>]

* Johannes Weiner <hannes@cmpxchg.org> wrote:

> Maintainers often repeat the same feedback on poorly written
> changelogs - describe the problem, justify your changes, quantify
> optimizations, describe user-visible changes - but our documentation
> on writing changelogs doesn't include these things.  Fix that.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> ---
>  Documentation/SubmittingPatches | 38 +++++++++++++++++++++++++++++++-------
>  1 file changed, 31 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
> index dcadffcab2dc..0a523c9a5ff4 100644
> --- a/Documentation/SubmittingPatches
> +++ b/Documentation/SubmittingPatches
> @@ -84,18 +84,42 @@ is another popular alternative.
>  
>  2) Describe your changes.
>  
> -Describe the technical detail of the change(s) your patch includes.
> -
> -Be as specific as possible.  The WORST descriptions possible include
> -things like "update driver X", "bug fix for driver X", or "this patch
> -includes updates for subsystem X.  Please apply."
> +Describe your problem.  Whether your patch is a one-line bug fix or
> +5000 lines of a new feature, there must be an underlying problem that
> +motivated you to do this work.  Convince the reviewer that there is a
> +problem worth fixing and that it makes sense for them to read past the
> +first paragraph.
> +
> +Describe user-visible impact.  Straight up crashes and lockups are
> +pretty convincing, but not all bugs are that blatant.  Even if the
> +problem was spotted during code review, describe the impact you think
> +it can have on users.  Keep in mind that the majority of Linux
> +installations run kernels from secondary stable trees or
> +vendor/product-specific trees that cherry-pick only specific patches
> +from upstream, so include anything that could help route your change
> +downstream: provoking circumstances, excerpts from dmesg, crash
> +descriptions, performance regressions, latency spikes, lockups, etc.
> +
> +Quantify optimizations and trade-offs.  If you claim improvements in
> +performance, memory consumption, stack footprint, or binary size,
> +include numbers that back them up.  But also describe non-obvious
> +costs.  Optimizations usually aren't free but trade-offs between CPU,
> +memory, and readability; or, when it comes to heuristics, between
> +different workloads.  Describe the expected downsides of your
> +optimization so that the reviewer can weigh costs against benefits.
> +
> +Once the problem is established, describe what you are actually doing
> +about it in technical detail.  It's important to describe the change
> +in plain English for the reviewer to verify that the code is behaving
> +as you intend it to.
>  
>  The maintainer will thank you if you write your patch description in a
>  form which can be easily pulled into Linux's source code management
>  system, git, as a "commit log".  See #15, below.
>  
> -If your description starts to get long, that's a sign that you probably
> -need to split up your patch.  See #3, next.
> +Solve only one problem per patch.  If your description starts to get
> +long, that's a sign that you probably need to split up your patch.
> +See #3, next.
>  
>  When you submit or resubmit a patch or patch series, include the
>  complete patch description and justification for it.  Don't just

Acked-by: Ingo Molnar <mingo@kernel.org>

Thanks,

	Ingo