[PATCH 2/2] tuntap: limit the number of flow caches
From: Jason Wang <hidden>
Date: 2013-01-23 14:07:59
Also in:
lkml
Subsystem:
networking drivers, the rest, tun/tap driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Willem de Bruijn, Jason Wang
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 <redacted> --- drivers/net/tun.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 8939d21..cc09b67 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))
--
1.7.1