Linux 5.5=rc1 kselftest rseq test build failure

[Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>]

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

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