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authorEric Dumazet <eric.dumazet@gmail.com>2010-12-06 09:29:43 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2011-01-07 13:58:27 -0800
commit414bdc25810282f9cf56a3335e695c263e487727 (patch)
tree6b0e48246096d87c42579b49957b64b3d73b1b6b /net
parent3e73328da09594bc4d40736c8b05c845558f0074 (diff)
filter: fix sk_filter rcu handling
[ Upstream commit 46bcf14f44d8f31ecfdc8b6708ec15a3b33316d9 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'net')
-rw-r--r--net/core/filter.c19
1 files changed, 6 insertions, 13 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index f68e49774829..71a433cdf7d3 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
@@ -650,7 +643,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
rcu_read_unlock_bh();
if (old_fp)
- sk_filter_delayed_uncharge(sk, old_fp);
+ sk_filter_uncharge(sk, old_fp);
return 0;
}
EXPORT_SYMBOL_GPL(sk_attach_filter);
@@ -664,7 +657,7 @@ int sk_detach_filter(struct sock *sk)
filter = rcu_dereference_bh(sk->sk_filter);
if (filter) {
rcu_assign_pointer(sk->sk_filter, NULL);
- sk_filter_delayed_uncharge(sk, filter);
+ sk_filter_uncharge(sk, filter);
ret = 0;
}
rcu_read_unlock_bh();