Re: Patches potentially missing from stable releases

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Aug 28, 2019 at 06:43:43AM -0700, Guenter Roeck wrote:
> On 8/28/19 1:41 AM, Greg Kroah-Hartman wrote:
> > On Tue, Aug 27, 2019 at 01:48:41PM -0700, Guenter Roeck wrote:
> > > On Tue, Aug 27, 2019 at 10:29:01PM +0200, Greg Kroah-Hartman wrote:
> > > > On Tue, Aug 27, 2019 at 01:01:51PM -0700, Guenter Roeck wrote:
> > > > > On Tue, Aug 27, 2019 at 02:10:03PM -0400, Sasha Levin wrote:
> > > > > > On Tue, Aug 27, 2019 at 10:16:21AM -0700, Guenter Roeck wrote:
> > > > > > > Hi,
> > > > > > > 
> > > > > > > I recently wrote a script which identifies patches potentially missing
> > > > > > > in downstream kernel branches. The idea is to identify patches backported/
> > > > > > > applied to a downstream branch for which patches tagged with Fixes: are
> > > > > > > available in the upstream kernel, but those fixes are missing from the
> > > > > > > downstream branch. The script workflow is something like:
> > > > > > > 
> > > > > > > - Identify locally applied patches in downstream branch
> > > > > > > - For each patch, identify the matching upstream SHA
> > > > > > > - Search the upstream kernel for Fixes: tags with this SHA
> > > > > > > - If one or more patches with matching Fixes: tags are found, check
> > > > > > > if the patch was applied to the downstream branch.
> > > > > > > - If the patch was not applied to the downstream branch, report
> > > > > > > 
> > > > > > > Running this script on chromeos-4.19 identified, not surprisingly, a number
> > > > > > > of such patches. However, and more surprisingly, it also identified several
> > > > > > > patches applied to v4.19.y for which fixes are available in the upstream
> > > > > > > kernel, but those fixes have not been applied to v4.19.y. Some of those
> > > > > > > are on the cosmetic side, but several seem to be relevant. I didn't
> > > > > > > cross-check all of them, but the ones I tried did apply to linux-4.19.y.
> > > > > > > The complete list is attached below.
> > > > > > > 
> > > > > > > Question: Do Sasha's automated scripts identify such patches ? If not,
> > > > > > > would it make sense to do it ? Or is there some reason why the patches
> > > > > > > have not been applied to v4.19.y ?
> > > > > > 
> > > > > > Hey Guenter,
> > > > > > 
> > > > > > I have a very similar script with a slight difference: I don't try to
> > > > > > find just "Fixes:" tags, but rather just any reference from one patch to
> > > > > > another. This tends to catch cases where once patch states it's "a
> > > > > > similar fix to ..." and such.
> > > > > > 
> > > > > > The tricky part is that it's causing a whole bunch of false positives,
> > > > > > which takes a while to weed through - and that's where the issue is
> > > > > > right now.
> > > > > > 
> > > > > 
> > > > > I didn't see any false positives, at least not yet. Would it possibly
> > > > > make sense to start with looking at Fixes: ? After all, additional
> > > > > references (wich higher chance for false positives) can always be
> > > > > searched for later.
> > > > 
> > > > I used to do this "by hand" with a tiny bit of automation, but need to
> > > > step it up and do it "correctly" like you did.
> > > > 
> > > > If you have a pointer to your script, I'd be glad to run it here locally
> > > > to keep track of this, like I do so for patches tagged with syzbot
> > > > issues.
> > > > 
> > > 
> > > I'd have to rewrite it to work with stable branches. Its current
> > > primary goal is to assist the rebase of one chromeos branch to
> > > a later upstream kernel release. I just repurposed part of it and
> > > use the generated databases to identify patches tagged with Fixes:.
> > > 
> > > I'll be happy to do that and make it work on stable branches in
> > > general if you think it would add value.
> > 
> > No worries, I can add the functionality to my local scripts that I have.
> > If you just had happened to have it in stand-alone format, it would have
> > saved me 30 minutes or so :)
> > 
> 
> I'll do it anyway. Already almost done. You are apparently better than me,
> though. It takes me a bit more than 30 minutes, but then I am using the
> opportunity to improve the scripts a bit. I'll publish the whole thing
> at github once complete.

I'm not saying it would be 30 minutes "from scratch", as I already have
most of this all working already as I am doing this today for the syzbot
stuff:
	https://github.com/gregkh/gregkh-linux/blob/master/scripts/syzbot_search

A "real" script would be wonderful to have, thanks!

thanks,

greg k-h