From: Alexei Starovoitov <ast@kernel.org>
Date: Fri, 30 Dec 2022 03:12:17 +0000 (-0800)
Subject: libbpf: Restore errno after pr_warn.
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bb5747cfbc4b7fe29621ca6cd4a695d2723bf2e8;p=linux.git

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 98333a6c38e93..e4d05662a96ce 100644
--- 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;
 }