From: Jason Wang <jasowang@redhat.com>
To: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Jason Wang <jasowang@redhat.com>,
Stephen Hemminger <stephen@networkplumber.org>
Subject: [PATCH 2/2] tuntap: limit the number of flow caches
Date: Wed, 23 Jan 2013 21:59:13 +0800 [thread overview]
Message-ID: <1358949553-30309-2-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1358949553-30309-1-git-send-email-jasowang@redhat.com>
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>
---
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
next prev parent reply other threads:[~2013-01-23 14:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-23 13:59 [PATCH 1/2] tuntap: reduce memory using of queues Jason Wang
2013-01-23 13:59 ` Jason Wang [this message]
2013-01-23 18:50 ` [PATCH 2/2] tuntap: limit the number of flow caches David Miller
2013-01-24 3:22 ` Jason Wang
2013-01-23 15:16 ` [PATCH 1/2] tuntap: reduce memory using of queues Michael S. Tsirkin
2013-01-23 18:47 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1358949553-30309-2-git-send-email-jasowang@redhat.com \
--to=jasowang@redhat.com \
--cc=davem@davemloft.net \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=stephen@networkplumber.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).