[PATCH bpf-next v1 03/19] selftests/bpf: Fix error compiling bpf_iter_setsockopt.c with musl libc

[Tony Ambardar]

Existing code calls getsockname() with a 'struct sockaddr_in6 *' argument
where a 'struct sockaddr *' argument is declared, yielding compile errors
when building for mips64el/musl-libc:

  bpf_iter_setsockopt.c: In function 'get_local_port':
  bpf_iter_setsockopt.c:98:30: error: passing argument 2 of 'getsockname' from 
incompatible pointer type [-Werror=incompatible-pointer-types]
     98 |         if (!getsockname(fd, &addr, &addrlen))
        |                              ^~~~~
        |                              |
        |                              struct sockaddr_in6 *
  In file included from .../netinet/in.h:10,
                   from .../arpa/inet.h:9,
                   from ./test_progs.h:17,
                   from bpf_iter_setsockopt.c:5:
  .../sys/socket.h:391:23: note: expected 'struct sockaddr * restrict' but 
argument is of type 'struct sockaddr_in6 *'
    391 | int getsockname (int, struct sockaddr *__restrict, socklen_t 
*__restrict);
        |                       ^
  cc1: all warnings being treated as errors

This compiled under glibc only because the argument is declared to be a
"funky" transparent union which includes both types above. Explicitly cast
the argument to allow compiling for both musl and glibc.

Fixes: eed92afdd14c ("bpf: selftest: Test batching and bpf_(get|set)sockopt in 
bpf tcp iter")
Signed-off-by: Tony Ambardar <tony.ambar...@gmail.com>
---
 tools/testing/selftests/bpf/prog_tests/bpf_iter_setsockopt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter_setsockopt.c 
b/tools/testing/selftests/bpf/prog_tests/bpf_iter_setsockopt.c
index b52ff8ce34db..35363b104dd2 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter_setsockopt.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter_setsockopt.c
@@ -95,7 +95,7 @@ static unsigned short get_local_port(int fd)
        struct sockaddr_in6 addr;
        socklen_t addrlen = sizeof(addr);
 
-       if (!getsockname(fd, &addr, &addrlen))
+       if (!getsockname(fd, (struct sockaddr *) &addr, &addrlen))
                return ntohs(addr.sin6_port);
 
        return 0;
-- 
2.34.1