On Wed, Oct 13, 2021 at 04:47:55PM +0200, Matthieu Baerts wrote:
Hi Greg, Sasha,
First, thank you for your great job maintaining the stable versions!
In our work related to MPTCP, we were wondering if we should/can add the "Fixes" tag for trivial/stable fixes.
It is certainly easier to explain that with an example: we have a small patch [1] to stop exposing a function that is only used from one .c file and declared there too. So the signature is removed from the .h file and the 'static' keyword is added in the .c file. It should have been like that since the introduction of this function.
We don't know if we can/should add the "Fixes" tag for such cases: the "mistake" has been introduced by one specific commit so we could add the "Fixes" tag but we also know patches with such tags are certainly going to be automatically backported. The patch is not really fixing a bug, more a "cleaning". Does it make sense to backport these patches then?
On one hand, we might think it would be interesting to backport it to reduce the differences with the last version: if the idea is to backport simple fixes to ease future and maybe more complex backports later. But on the other hand, it is more work for you to backport it: if the idea is to backport only actual bug-fix patches. So what is the preferred policy?
We didn't find anything in the doc on "when not to add the 'Fixes' tag" but we know the Stable Kernel Rules doc mentions to avoid trivial fixes. Maybe this patch is not "trivial", it is not really a bug-fix either but that's not the real question here, more: does this rule -- and other ones from Stable Kernel doc -- apply to the "Fixes" tag as well?
Please use the Fixes: tag whenever you want to. Having it there does NOT mean the patch is automatically backported to stable releases, we look at them all and choose if they are valid or not.
There are lots of tiny "Fixes:" commits that we do not backport for obvious reasons that they do not fit the stable kernel requirements.
If you know a patch should be backported to a stable tree, then put the cc: stable on it, as documented. Again, "Fixes:" is no guarantee that a commit will be backported at all.
thanks,
greg k-h