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authorJakub Kicinski <jakub.kicinski@netronome.com>2017-10-09 10:30:14 -0700
committerDavid S. Miller <davem@davemloft.net>2017-10-10 12:30:16 -0700
commitd66f2b91f95b56e31772b9faa0d036cd2e53cb02 (patch)
tree7443577f00bc649d464047dba4b3ece5fa0fb7e2 /net/core
parentc9c35995bcf812ee8136f634c25bc6ccc3021d4c (diff)
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')
-rw-r--r--net/core/dst.c16
-rw-r--r--net/core/filter.c16
2 files changed, 25 insertions, 7 deletions
diff --git a/net/core/dst.c b/net/core/dst.c
index a6c47da7d0f8..8b2eafac984d 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -322,3 +322,19 @@ metadata_dst_alloc_percpu(u8 optslen, enum metadata_type type, gfp_t flags)
return md_dst;
}
EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);
+
+void metadata_dst_free_percpu(struct metadata_dst __percpu *md_dst)
+{
+ int cpu;
+
+#ifdef CONFIG_DST_CACHE
+ for_each_possible_cpu(cpu) {
+ struct metadata_dst *one_md_dst = per_cpu_ptr(md_dst, cpu);
+
+ if (one_md_dst->type == METADATA_IP_TUNNEL)
+ dst_cache_destroy(&one_md_dst->u.tun_info.dst_cache);
+ }
+#endif
+ free_percpu(md_dst);
+}
+EXPORT_SYMBOL_GPL(metadata_dst_free_percpu);
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) {