diff options
| author |   Jakub Kicinski <jakub.kicinski@netronome.com> | 2017-10-09 10:30:14 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-10-10 12:30:16 -0700 |
| commit | d66f2b91f95b56e31772b9faa0d036cd2e53cb02 (patch) | |
| tree | 7443577f00bc649d464047dba4b3ece5fa0fb7e2 /net/core/filter.c | |
| parent | tools: bpftool: use the kernel's instruction printer (diff) | |
| download | linux-dev-d66f2b91f95b56e31772b9faa0d036cd2e53cb02.tar.xz linux-dev-d66f2b91f95b56e31772b9faa0d036cd2e53cb02.zip | |
bpf: don't rely on the verifier lock for metadata_dst allocation
bpf_skb_set_tunnel_*() functions require allocation of per-cpu
metadata_dst. The allocation happens upon verification of the
first program using those helpers. In preparation for removing
the verifier lock, use cmpxchg() to make sure we only allocate
the metadata_dsts once.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/filter.c')
| -rw-r--r-- | net/core/filter.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index b7e8caa1e790..140fa9f9c0f4 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -43,6 +43,7 @@ #include <linux/timer.h> #include <linux/uaccess.h> #include <asm/unaligned.h> +#include <asm/cmpxchg.h> #include <linux/filter.h> #include <linux/ratelimit.h> #include <linux/seccomp.h> @@ -2987,14 +2988,15 @@ static const struct bpf_func_proto * bpf_get_skb_set_tunnel_proto(enum bpf_func_id which) { if (!md_dst) { - /* Race is not possible, since it's called from verifier - * that is holding verifier mutex. - */ - md_dst = metadata_dst_alloc_percpu(IP_TUNNEL_OPTS_MAX, - METADATA_IP_TUNNEL, - GFP_KERNEL); - if (!md_dst) + struct metadata_dst __percpu *tmp; + + tmp = metadata_dst_alloc_percpu(IP_TUNNEL_OPTS_MAX, + METADATA_IP_TUNNEL, + GFP_KERNEL); + if (!tmp) return NULL; + if (cmpxchg(&md_dst, NULL, tmp)) + metadata_dst_free_percpu(tmp); } switch (which) { |