diff options
| author | Daniel Borkmann | 2016-11-09 22:02:34 +0100 |
|---|---|---|
| committer | David S. Miller | 2016-11-12 23:31:57 -0500 |
| commit | c540594f864bb4645573c2c0a304919fabb3d7ea (patch) | |
| tree | bbc81f35747fb25416c9015d23fc7071d54feb11 /kernel/bpf | |
| parent | b602e491a518439abd98a25ccded85e1347b9a14 (diff) | |
bpf, mlx4: fix prog refcount in mlx4_en_try_alloc_resources error path
Commit 67f8b1dcb9ee ("net/mlx4_en: Refactor the XDP forwarding rings
scheme") added a bug in that the prog's reference count is not dropped
in the error path when mlx4_en_try_alloc_resources() is failing from
mlx4_xdp_set().
We previously took bpf_prog_add(prog, priv->rx_ring_num - 1), that we
need to release again. Earlier in the call path, dev_change_xdp_fd()
itself holds a reference to the prog as well (hence the '- 1' in the
bpf_prog_add()), so a simple atomic_sub() is safe to use here. When
an error is propagated, then bpf_prog_put() is called eventually from
dev_change_xdp_fd()
Fixes: 67f8b1dcb9ee ("net/mlx4_en: Refactor the XDP forwarding rings scheme")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/syscall.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 228f962447a5..23eb2050f15e 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -680,6 +680,17 @@ struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i) } EXPORT_SYMBOL_GPL(bpf_prog_add); +void bpf_prog_sub(struct bpf_prog *prog, int i) +{ + /* Only to be used for undoing previous bpf_prog_add() in some + * error path. We still know that another entity in our call + * path holds a reference to the program, thus atomic_sub() can + * be safely used in such cases! + */ + WARN_ON(atomic_sub_return(i, &prog->aux->refcnt) == 0); +} +EXPORT_SYMBOL_GPL(bpf_prog_sub); + struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog) { return bpf_prog_add(prog, 1); |