From 2f5825cb38028a14961a79844a069be4e3057eca Mon Sep 17 00:00:00 2001 From: Andrea Claudi Date: Tue, 21 Sep 2021 11:33:24 +0200 Subject: [PATCH] lib: bpf_legacy: fix bpffs mount when /sys/fs/bpf exists MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit bpf selftests using iproute2 fails with: $ ip link set dev veth0 xdp object ../bpf/xdp_dummy.o section xdp_dummy Continuing without mounted eBPF fs. Too old kernel? mkdir (null)/globals failed: No such file or directory Unable to load program This happens when the /sys/fs/bpf directory exists. In this case, mkdir in bpf_mnt_check_target() fails with errno == EEXIST, and the function returns -1. Thus bpf_get_work_dir() does not call bpf_mnt_fs() and the bpffs is not mounted. Fix this in bpf_mnt_check_target(), returning 0 when the mountpoint exists. Fixes: d4fcdbbec9df ("lib/bpf: Fix and simplify bpf_mnt_check_target()") Reported-by: Mingyu Shi Reported-by: Jiri Benc Suggested-by: Jiri Benc Signed-off-by: Andrea Claudi Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Stephen Hemminger --- lib/bpf_legacy.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/lib/bpf_legacy.c b/lib/bpf_legacy.c index 91086aa2..275941dd 100644 --- a/lib/bpf_legacy.c +++ b/lib/bpf_legacy.c @@ -513,9 +513,12 @@ static int bpf_mnt_check_target(const char *target) int ret; ret = mkdir(target, S_IRWXU); - if (ret && errno != EEXIST) + if (ret) { + if (errno == EEXIST) + return 0; fprintf(stderr, "mkdir %s failed: %s\n", target, strerror(errno)); + } return ret; }