Re: nfs: add dummy definition for nfsd_file

Pali Rohár
2025-03-27T08:28:48Z

On Wednesday 26 March 2025 22:00:02 Mike Snitzer wrote:
> On Wed, Mar 26, 2025 at 09:59:19PM +0100, Pali Rohár wrote:
> > On Wednesday 26 March 2025 08:33:32 Jeff Johnson wrote:
> > > On 3/26/2025 8:09 AM, Mike Snitzer wrote:
> > > > Add dummy definition for nfsd_file in both nfslocalio.c and localio.c
> > > > so older gcc (e.g. EL8's 8.5.0) can be used. Older gcc causes RCU
> > > > code (rcu_dereference and rcu_access_pointer) to dereference what
> > > > should just be an opaque pointer with its use of typeof.
> > > >
> > > > So without the dummy definition compiling with older gcc fails.
> > > >
> > > > Link: https://lore.kernel.org/all/Zsyhco1OrOI_uSbd@kernel.org/
> > > > Fixes: 55a9742d02eff ("nfs: cache all open LOCALIO nfsd_file(s) in client")
> >
> > As this change is fixing compile error, should not be there also cc: stable line?
>
> Any commit with a Fixes: tag will automatically be picked up by
> stable@ once it is merged. An explicit cc: sttable@ would be
> redundant.

From my experience, when the backporting of commit with both Fixes:+Cc:
fails then the committer of the patch and also other is informed by
robot email. If there is only Fixes: without Cc: then people are not
informed.

So I used the Fixes:+Cc: for such build issues or important issues to
ensure that the change is really backported.

> > >
> > > I saw this issue using crosstools/gcc-13.3.0-nolibc and this patch fixes it.
> >
> > So maybe the commit message can be adjusted, so it does not say only
> > "older gcc"?
>
> I don't see the need to list all compilers, I documented the compiler
> that motivated my fix. Fact that it applicable for
> crosstools/gcc-13.3.0-nolibc (which I don't have context for what it
> is.. but if this commit is needed for it then it is a suspect "new"
> compiler).

My impression was that the commit is fixing just the compilation with
old gcc versions. But it seems that also new are affected. That is why I
suggested to adjust it, so it would be clear that it applies for new gcc
versions too.

> > > Tested-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
> >
> > I have tested this change and it fixed compilation for me too. So:
> >
> > Tested-by: Pali Rohár <pali@kernel.org>
> >
> > >
> > > > Signed-off-by: Mike Snitzer <snitzer@hammerspace.com>
> > >
> > > note this doesn't match the From: address
>
> AFAIK there is no requirement that an S-o-B tag must match the email
> header's From.
>
> Mike