[PATCH bpf-next v4 2/2] xsk: support BPF_EXIST and BPF_NOEXIST flags in XSKMAP
From: Björn Töpel <hidden>
Date: 2019-08-02 08:12:22
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
From: Björn Töpel <redacted> The XSKMAP did not honor the BPF_EXIST/BPF_NOEXIST flags when updating an entry. This patch addresses that. Signed-off-by: Björn Töpel <redacted> --- kernel/bpf/xskmap.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c
index 780639309f6b..8864dfe1d9ef 100644
--- a/kernel/bpf/xskmap.c
+++ b/kernel/bpf/xskmap.c@@ -226,8 +226,6 @@ static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value, return -EINVAL; if (unlikely(i >= m->map.max_entries)) return -E2BIG; - if (unlikely(map_flags == BPF_NOEXIST)) - return -EEXIST; sock = sockfd_lookup(fd, &err); if (!sock)
@@ -253,14 +251,29 @@ static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value, } spin_lock_bh(&m->lock); + entry = &m->xsk_map[i]; + old_xs = READ_ONCE(*entry); + if (old_xs && map_flags == BPF_NOEXIST) { + err = -EEXIST; + goto out; + } else if (!old_xs && map_flags == BPF_EXIST) { + err = -ENOENT; + goto out; + } xsk_map_sock_add(xs, node); - old_xs = xchg(entry, xs); + WRITE_ONCE(*entry, xs); if (old_xs) xsk_map_sock_delete(old_xs, entry); spin_unlock_bh(&m->lock); sockfd_put(sock); return 0; + +out: + spin_unlock_bh(&m->lock); + sockfd_put(sock); + xsk_map_node_free(node); + return err; } static int xsk_map_delete_elem(struct bpf_map *map, void *key)
--
2.20.1