The defination of swap() is used from kernel's internal header when this test is built in source tree. The build fails when this test is built out of source tree as defination of swap() isn't found. Selftests shouldn't depend on kernel's internal header files. They can only depend on uapi header files. Add the defination of swap() to fix the build error:
gcc -Wall -I/linux_mainline2/build/usr/include -no-pie userfaultfd.c -lrt -lpthread -o /linux_mainline2/build/kselftest/vm/userfaultfd userfaultfd.c: In function ‘userfaultfd_stress’: userfaultfd.c:1530:3: warning: implicit declaration of function ‘swap’; did you mean ‘swab’? [-Wimplicit-function-declaration] 1530 | swap(area_src, area_dst); | ^~~~ | swab /usr/bin/ld: /tmp/cclUUH7V.o: in function `userfaultfd_stress': userfaultfd.c:(.text+0x4d64): undefined reference to `swap' /usr/bin/ld: userfaultfd.c:(.text+0x4d82): undefined reference to `swap' collect2: error: ld returned 1 exit status
Fixes: 2c769ed7137a ("tools/testing/selftests/vm/userfaultfd.c: use swap() to make code cleaner") Signed-off-by: Muhammad Usama Anjum usama.anjum@collabora.com --- tools/testing/selftests/vm/userfaultfd.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index d3fd24f9fae8..d2480ab93037 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -119,6 +119,9 @@ struct uffd_stats { ~(unsigned long)(sizeof(unsigned long long) \ - 1)))
+#define swap(a, b) \ + do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) + const char *examples = "# Run anonymous memory test on 100MiB region with 99999 bounces:\n" "./userfaultfd anon 100 99999\n\n"