Re: [PATCH 4.19.y] selftests: bpf: fix use of undeclared RET_IF macro

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Jun 10, 2020 at 02:34:16PM +0100, Lorenz Bauer wrote:
> On Wed, 10 Jun 2020 at 13:24, Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Wed, Jun 10, 2020 at 01:10:14PM +0100, Lorenz Bauer wrote:
> > > On Wed, 10 Jun 2020 at 12:50, Greg KH <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Wed, Jun 10, 2020 at 11:16:16AM +0100, Lorenz Bauer wrote:
> > > > > On Fri, 22 May 2020 at 01:09, Sasha Levin <sashal@kernel.org> wrote:
> > > > > >
> > > > > > On Thu, May 21, 2020 at 03:48:41PM +0100, Lorenz Bauer wrote:
> > > > > > >commit 634efb750435 ("selftests: bpf: Reset global state between
> > > > > > >reuseport test runs") uses a macro RET_IF which doesn't exist in
> > > > > > >the v4.19 tree. It is defined as follows:
> > > > > > >
> > > > > > >        #define RET_IF(condition, tag, format...) ({
> > > > > > >                if (CHECK_FAIL(condition)) {
> > > > > > >                        printf(tag " " format);
> > > > > > >                        return;
> > > > > > >                }
> > > > > > >        })
> > > > > > >
> > > > > > >CHECK_FAIL in turn is defined as:
> > > > > > >
> > > > > > >        #define CHECK_FAIL(condition) ({
> > > > > > >                int __ret = !!(condition);
> > > > > > >                int __save_errno = errno;
> > > > > > >                if (__ret) {
> > > > > > >                        test__fail();
> > > > > > >                        fprintf(stdout, "%s:FAIL:%d\n", __func__, __LINE__);
> > > > > > >                }
> > > > > > >                errno = __save_errno;
> > > > > > >                __ret;
> > > > > > >        })
> > > > > > >
> > > > > > >Replace occurences of RET_IF with CHECK. This will abort the test binary
> > > > > > >if clearing the intermediate state fails.
> > > > > > >
> > > > > > >Fixes: 634efb750435 ("selftests: bpf: Reset global state between reuseport test runs")
> > > > > > >Reported-by: kernel test robot <rong.a.chen@intel.com>
> > > > > > >Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
> > > > > >
> > > > > > Thanks for the backport Lorenz. We'll need to wait for it to make it
> > > > > > into Linus's tree before queueing up for the stable trees.
> > > > >
> > > > > Apologies for sending the patch too early (?), I'm still new to this process.
> > > > > I've just hit this on 4.19.127. Do you want me to re-submit the patch somewhere?
> > > >
> > > > Is this patch in Linus's tree yet?  If so, just tell us the git commit
> > > > id.  If not, it needs to go there first before we can take it to any
> > > > stable tree.
> > >
> > > The patch isn't in Linus' tree because the problem doesn't exist
> > > there. It fixes a build problem on
> > > v4.19 which was introduced by the backport of an earlier fix of mine,
> > > commit 634efb750435
> > > ("selftests: bpf: Reset global state between reuseport test runs").
> > >
> > > There is a similar fix from Andrii Nakryiko that went into 5.4 as
> > > commit aee43146cc10
> > > ("selftest/bpf: fix backported test_select_reuseport selftest
> > > changes"), which I hadn't seen
> > > at the time.
> >
> > Ah, ok, that wasn't very obvious, sorry.  I'll queue this up after the
> > next round of kernels are released in a day or so...
> 
> No, it was my bad. What can I do to avoid this next time?

Be _VERY_ explicit as to why this is only a 4.19 patch, and what this
means, and why it is so.  We see hundreds of patches a day, and almost
none of them are this type of "special" case, so it must have to
stand-out as you are doing something not very usual.

thanks,

greg k-h