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| author | Björn Töpel <bjorn.topel@intel.com> | 2018-10-08 19:40:16 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-10-11 10:19:01 +0200 |
| commit | cee271678d0e3177a25d0fcb2fa5e051d48e4262 (patch) | |
| tree | b63781801b81ccc68cda0d24417764e90ec138c1 | |
| parent | 262f9d811c7608f1e74258ceecfe1fa213bdf912 (diff) | |
| download | linux-0-day-cee271678d0e3177a25d0fcb2fa5e051d48e4262.tar.gz linux-0-day-cee271678d0e3177a25d0fcb2fa5e051d48e4262.tar.xz | |
xsk: do not call synchronize_net() under RCU read lock
The XSKMAP update and delete functions called synchronize_net(), which
can sleep. It is not allowed to sleep during an RCU read section.
Instead we need to make sure that the sock sk_destruct (xsk_destruct)
function is asynchronously called after an RCU grace period. Setting
the SOCK_RCU_FREE flag for XDP sockets takes care of this.
Fixes: fbfc504a24f5 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
| -rw-r--r-- | kernel/bpf/xskmap.c | 10 | ||||
| -rw-r--r-- | net/xdp/xsk.c | 2 |
2 files changed, 4 insertions, 8 deletions
diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c index 9f8463afda9c8..47147c9e184dd 100644 --- a/kernel/bpf/xskmap.c +++ b/kernel/bpf/xskmap.c @@ -192,11 +192,8 @@ static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value, sock_hold(sock->sk); old_xs = xchg(&m->xsk_map[i], xs); - if (old_xs) { - /* Make sure we've flushed everything. */ - synchronize_net(); + if (old_xs) sock_put((struct sock *)old_xs); - } sockfd_put(sock); return 0; @@ -212,11 +209,8 @@ static int xsk_map_delete_elem(struct bpf_map *map, void *key) return -EINVAL; old_xs = xchg(&m->xsk_map[k], NULL); - if (old_xs) { - /* Make sure we've flushed everything. */ - synchronize_net(); + if (old_xs) sock_put((struct sock *)old_xs); - } return 0; } diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 4e937cd7c17dc..661504042d304 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -744,6 +744,8 @@ static int xsk_create(struct net *net, struct socket *sock, int protocol, sk->sk_destruct = xsk_destruct; sk_refcnt_debug_inc(sk); + sock_set_flag(sk, SOCK_RCU_FREE); + xs = xdp_sk(sk); mutex_init(&xs->mutex); spin_lock_init(&xs->tx_completion_lock); |