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authorJesper Dangaard Brouer <brouer@redhat.com>2013-03-27 05:55:25 +0000
committerDavid S. Miller <davem@davemloft.net>2013-03-27 12:48:33 -0400
commit68399ac37e571c2d695ea3b08aa82235874b5158 (patch)
tree03e6d64768df3178e8bb4ef897e5d8c6ca1cb24c
parent167bfa71844a7a7415da0fa8c75e672f3bd438c8 (diff)
downloadlinux-68399ac37e571c2d695ea3b08aa82235874b5158.tar.bz2
net: frag, avoid several CPUs grabbing same frag queue during LRU evictor loop
The LRU list is protected by its own lock, since commit 3ef0eb0db4 (net: frag, move LRU list maintenance outside of rwlock), and no-longer by a read_lock. This makes it possible, to remove the inet_frag_queue, which is about to be "evicted", from the LRU list head. This avoids the problem, of several CPUs grabbing the same frag queue. Note, cannot remove the inet_frag_lru_del() call in fq_unlink() called by inet_frag_kill(), because inet_frag_kill() is also used in other situations. Thus, we use list_del_init() to allow this double list_del to work. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/inet_fragment.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 2bff045bec60..8ba548a8efce 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -204,6 +204,9 @@ int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f, bool force)
q = list_first_entry(&nf->lru_list,
struct inet_frag_queue, lru_list);
atomic_inc(&q->refcnt);
+ /* Remove q from list to avoid several CPUs grabbing it */
+ list_del_init(&q->lru_list);
+
spin_unlock(&nf->lru_lock);
spin_lock(&q->lock);