libbpf: Restore errno after pr_warn.

pr_warn calls into user-provided callback, which can clobber errno, so
`errno = saved_errno` should happen after pr_warn.

Fixes: 07453245620c ("libbpf: fix errno is overwritten after being closed.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 98333a6..e4d0566 100644 (file)
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -544,8 +544,10 @@ static inline int ensure_good_fd(int fd)
                saved_errno = errno;
                close(old_fd);
                errno = saved_errno;
-               if (fd < 0)
+               if (fd < 0) {
                        pr_warn("failed to dup FD %d to FD > 2: %d\n", old_fd, -saved_errno);
+                       errno = saved_errno;
+               }
        }
        return fd;
 }