From 07453245620c075779abefa2a9f469fa336e7510 Mon Sep 17 00:00:00 2001 From: Xin Liu Date: Fri, 23 Dec 2022 21:36:18 +0800 Subject: [PATCH] libbpf: fix errno is overwritten after being closed. In the ensure_good_fd function, if the fcntl function succeeds but the close function fails, ensure_good_fd returns a normal fd and sets errno, which may cause users to misunderstand. The close failure is not a serious problem, and the correct FD has been handed over to the upper-layer application. Let's restore errno here. Signed-off-by: Xin Liu Link: https://lore.kernel.org/r/20221223133618.10323-1-liuxin350@huawei.com Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/libbpf_internal.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 377642f..98333a6 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -543,10 +543,9 @@ static inline int ensure_good_fd(int fd) fd = fcntl(fd, F_DUPFD_CLOEXEC, 3); saved_errno = errno; close(old_fd); - if (fd < 0) { + errno = saved_errno; + if (fd < 0) pr_warn("failed to dup FD %d to FD > 2: %d\n", old_fd, -saved_errno); - errno = saved_errno; - } } return fd; } -- 2.7.4