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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-12-06 17:29:43 (GMT) |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-12-06 17:29:43 (GMT) |
| commit | 46bcf14f44d8f31ecfdc8b6708ec15a3b33316d9 (patch) | |
| tree | 4d2a200387242e1ed2d95ccd367c77750379e8cc | |
| parent | e7dfc8dbdf9a7fa1ef04c63100a71f4102b82ed3 (diff) | |
| download | linux-46bcf14f44d8f31ecfdc8b6708ec15a3b33316d9.tar.xz | |
filter: fix sk_filter rcu handling
Pavel Emelyanov tried to fix a race between sk_filter_(de|at)tach and
sk_clone() in commit 47e958eac280c263397
Problem is we can have several clones sharing a common sk_filter, and
these clones might want to sk_filter_attach() their own filters at the
same time, and can overwrite old_filter->rcu, corrupting RCU queues.
We can not use filter->rcu without being sure no other thread could do
the same thing.
Switch code to a more conventional ref-counting technique : Do the
atomic decrement immediately and queue one rcu call back when last
reference is released.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/sock.h | 4 | ||||
| -rw-r--r-- | net/core/filter.c | 19 |
2 files changed, 9 insertions, 14 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index a6338d0..659d968d9 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1155,6 +1155,8 @@ extern void sk_common_release(struct sock *sk); /* Initialise core socket variables */ extern void sock_init_data(struct socket *sock, struct sock *sk); +extern void sk_filter_release_rcu(struct rcu_head *rcu); + /** * sk_filter_release - release a socket filter * @fp: filter to remove @@ -1165,7 +1167,7 @@ extern void sock_init_data(struct socket *sock, struct sock *sk); static inline void sk_filter_release(struct sk_filter *fp) { if (atomic_dec_and_test(&fp->refcnt)) - kfree(fp); + call_rcu_bh(&fp->rcu, sk_filter_release_rcu); } static inline void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp) diff --git a/net/core/filter.c b/net/core/filter.c index c1ee800..ae21a0d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -589,23 +589,16 @@ int sk_chk_filter(struct sock_filter *filter, int flen) EXPORT_SYMBOL(sk_chk_filter); /** - * sk_filter_rcu_release - Release a socket filter by rcu_head + * sk_filter_release_rcu - Release a socket filter by rcu_head * @rcu: rcu_head that contains the sk_filter to free */ -static void sk_filter_rcu_release(struct rcu_head *rcu) +void sk_filter_release_rcu(struct rcu_head *rcu) { struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); - sk_filter_release(fp); -} - -static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp) -{ - unsigned int size = sk_filter_len(fp); - - atomic_sub(size, &sk->sk_omem_alloc); - call_rcu_bh(&fp->rcu, sk_filter_rcu_release); + kfree(fp); } +EXPORT_SYMBOL(sk_filter_release_rcu); /** * sk_attach_filter - attach a socket filter @@ -649,7 +642,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) rcu_assign_pointer(sk->sk_filter, fp); if (old_fp) - sk_filter_delayed_uncharge(sk, old_fp); + sk_filter_uncharge(sk, old_fp); return 0; } EXPORT_SYMBOL_GPL(sk_attach_filter); @@ -663,7 +656,7 @@ int sk_detach_filter(struct sock *sk) sock_owned_by_user(sk)); if (filter) { rcu_assign_pointer(sk->sk_filter, NULL); - sk_filter_delayed_uncharge(sk, filter); + sk_filter_uncharge(sk, filter); ret = 0; } return ret; |