Re: Linux 5.5=rc1 kselftest rseq test build failure

[Shuah Khan]

On 12/11/19 8:19 AM, Mathieu Desnoyers wrote:
> ----- On Dec 10, 2019, at 7:27 PM, Shuah Khan skhan@xxxxxxxxxxxxxxxxxxx wrote:
>
> > Hi Mathieu,
> >
> > I am seeing rseq test build failure on Linux 5.5-rc1.
> >
> > gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./
> > param_test.c -lpthread -lrseq -o ...tools/testing/selftests/rseq/param_test
> > param_test.c:18:21: error: static declaration of âgettidâ follows
> > non-static declaration
> >     18 | static inline pid_t gettid(void)
> >        |                     ^~~~~~
> > In file included from /usr/include/unistd.h:1170,
> >                   from param_test.c:11:
> > /usr/include/x86_64-linux-gnu/bits/unistd_ext.h:34:16: note: previous
> > declaration of âgettidâ was here
> >     34 | extern __pid_t gettid (void) __THROW;
> >        |                ^~~~~~
> > make: *** [Makefile:28: ...tools/testing/selftests/rseq/param_test] Error 1
> >
> >
> > The following obvious change fixes it. However, there could be reason
> > why this was defined here. If you think this is the right fix, I can
> > send the patch. I started seeing this with gcc version 9.2.1 20191008
>
> This issue is caused by introduction of "gettid()" in glibc 2.30. I don't
> think we want to introduce a build dependency on glibc 2.30 for kernel
> selftests. Removing the gettid() symbol as you propose here will break
> build environments with glibc < 2.30.
>
> We could eventually try to figure out whether the glibc headers implement
> gettid() at build time (not sure how), or we could simply rename our own
> "gettid()" to "rseq_gettid()", thus removing the namespace clash with
> glibc.
>
> I can propose a patch renaming gettid() to rseq_gettid() is that approach
> is OK with you.

Looks like you already have a patch to do this. I see it in my Inbox.
I could take that.

thanks,
-- Shuah