Commit 0c047ecb authored May 31, 2020 by Jakub Sitnicki Committed by Alexei Starovoitov Jun 01, 2020

bpf, cgroup: Return ENOLINK for auto-detached links on update

Failure to update a bpf_link because it has been auto-detached by a dying
cgroup currently results in EINVAL error, even though the arguments passed
to bpf() syscall are not wrong.

bpf_links attaching to netns in this case will return ENOLINK, which
carries the message that the link is no longer attached to anything.

Change cgroup bpf_links to do the same to keep the uAPI errors consistent.

Fixes: 0c991ebc ("bpf: Implement bpf_prog replacement for an active bpf_cgroup_link")
Suggested-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200531082846.2117903-6-jakub@cloudflare.com

parent 7f045a49

kernel/bpf/cgroup.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -595,7 +595,7 @@ static int cgroup_bpf_replace(struct bpf_link link, struct bpf_prog new_prog,
		mutex_lock(&cgroup_mutex);
		/* link might have been auto-released by dying cgroup, so fail */
		if (!cg_link->cgroup) {
		ret = -EINVAL;
		ret = -ENOLINK;
		goto out_unlock;
		}
		if (old_prog && link->prog != old_prog) {

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