From: David Wragg <david-1SEAoVOfG6VEzL6FDj/jAg@public.gmane.org>
To: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
dev-yBygre7rU0TnMu66kgdUjQ@public.gmane.org
Cc: David Wragg <david-1SEAoVOfG6VEzL6FDj/jAg@public.gmane.org>,
Tom Herbert <tom-BjP2VixgY4xUbtYUoyoikg@public.gmane.org>
Subject: [PATCH net] geneve: Refine MTU limit
Date: Tue, 16 Feb 2016 12:33:19 +0000 [thread overview]
Message-ID: <1455625999-9781-1-git-send-email-david@weave.works> (raw)
While GENEVE allows variable length options, the maximum length of the
options is 63 * 4 bytes. So we can reasonably set an MTU limit other
than IP_MAX_MTU, as the other tunnel devices do.
Signed-off-by: David Wragg <david@weave.works>
---
drivers/net/geneve.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 028e387..f57f9bc 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -37,6 +37,9 @@ MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
#define GENEVE_VER 0
#define GENEVE_BASE_HLEN (sizeof(struct udphdr) + sizeof(struct genevehdr))
+#define GENEVE_MAX_OPTIONS_LEN (63 * 4)
+#define GENEVE_MAX_MTU (IP_MAX_MTU - sizeof(struct iphdr) - GENEVE_BASE_HLEN \
+ - GENEVE_MAX_OPTIONS_LEN)
/* per-network namespace private data for this module */
struct geneve_net {
@@ -1041,11 +1044,9 @@ static netdev_tx_t geneve_xmit(struct sk_buff *skb, struct net_device *dev)
static int geneve_change_mtu(struct net_device *dev, int new_mtu)
{
- /* GENEVE overhead is not fixed, so we can't enforce a more
- * precise max MTU.
- */
- if (new_mtu < 68 || new_mtu > IP_MAX_MTU)
+ if (new_mtu < 68 || new_mtu > GENEVE_MAX_MTU)
return -EINVAL;
+
dev->mtu = new_mtu;
return 0;
}
@@ -1459,7 +1460,7 @@ struct net_device *geneve_dev_create_fb(struct net *net, const char *name,
/* openvswitch users expect packet sizes to be unrestricted,
* so set the largest MTU we can.
*/
- err = geneve_change_mtu(dev, IP_MAX_MTU);
+ err = geneve_change_mtu(dev, GENEVE_MAX_MTU);
if (err)
goto err;
--
2.5.0
_______________________________________________
dev mailing list
dev@openvswitch.org
http://openvswitch.org/mailman/listinfo/dev
next reply other threads:[~2016-02-16 12:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-16 12:33 David Wragg [this message]
[not found] ` <1455625999-9781-1-git-send-email-david-1SEAoVOfG6VEzL6FDj/jAg@public.gmane.org>
2016-02-16 18:32 ` [PATCH net] geneve: Refine MTU limit Jesse Gross
2016-02-18 16:41 ` David Wragg
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=1455625999-9781-1-git-send-email-david@weave.works \
--to=david-1seaovofg6vezl6fdj/jag@public.gmane.org \
--cc=dev-yBygre7rU0TnMu66kgdUjQ@public.gmane.org \
--cc=netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=tom-BjP2VixgY4xUbtYUoyoikg@public.gmane.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).