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authorJason Wang <jasowang@redhat.com>2013-01-23 03:59:13 +0000
committerDavid S. Miller <davem@davemloft.net>2013-01-23 13:47:06 -0500
commitb8732fb7f8920e2f6216d2b67faf8b0b0d67ca81 (patch)
tree9e4f5052cea423ec1302e2175211d58adee0e300 /drivers/net/tun.c
parentedfb6a148ce62e5e19354a1dcd9a34e00815c2a1 (diff)
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tuntap: limit the number of flow caches
We create new flow caches when a new flow is identified by tuntap, This may lead some issues: - userspace may produce a huge amount of short live flows to exhaust host memory - the unlimited number of flow caches may produce a long list which increase the time in the linear searching Solve this by introducing a limit of total number of flow caches. Cc: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tun.c')
-rw-r--r--drivers/net/tun.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 8939d2117de..cc09b67c23b 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -113,6 +113,7 @@ struct tap_filter {
* the netdevice to be fit in one page. So we can make sure the success of
* memory allocation. TODO: increase the limit. */
#define MAX_TAP_QUEUES DEFAULT_MAX_NUM_RSS_QUEUES
+#define MAX_TAP_FLOWS 4096
#define TUN_FLOW_EXPIRE (3 * HZ)
@@ -185,6 +186,7 @@ struct tun_struct {
unsigned int numdisabled;
struct list_head disabled;
void *security;
+ u32 flow_count;
};
static inline u32 tun_hashfn(u32 rxhash)
@@ -218,6 +220,7 @@ static struct tun_flow_entry *tun_flow_create(struct tun_struct *tun,
e->queue_index = queue_index;
e->tun = tun;
hlist_add_head_rcu(&e->hash_link, head);
+ ++tun->flow_count;
}
return e;
}
@@ -228,6 +231,7 @@ static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e)
e->rxhash, e->queue_index);
hlist_del_rcu(&e->hash_link);
kfree_rcu(e, rcu);
+ --tun->flow_count;
}
static void tun_flow_flush(struct tun_struct *tun)
@@ -317,7 +321,8 @@ static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
e->updated = jiffies;
} else {
spin_lock_bh(&tun->lock);
- if (!tun_flow_find(head, rxhash))
+ if (!tun_flow_find(head, rxhash) &&
+ tun->flow_count < MAX_TAP_FLOWS)
tun_flow_create(tun, head, rxhash, queue_index);
if (!timer_pending(&tun->flow_gc_timer))