----- On Dec 10, 2019, at 7:27 PM, Shuah Khan skhan@linuxfoundation.org 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 ‘gettid’ 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 ‘gettid’ 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.

Thanks,

Mathieu

diff --git a/tools/testing/selftests/rseq/param_test.c b/tools/testing/selftests/rseq/param_test.c index eec2663261f2..18a0fa1235a7 100644 --- a/tools/testing/selftests/rseq/param_test.c +++ b/tools/testing/selftests/rseq/param_test.c @@ -15,11 +15,6 @@ #include <errno.h> #include <stddef.h>

-static inline pid_t gettid(void) -{

•   return syscall(__NR_gettid);
  

-}

thanks, -- Shuah