From: Pavel Emelyanov <xemul@parallels•com>
To: David Miller <davem@davemloft•net>,
Eric Dumazet <eric.dumazet@gmail•com>,
"Eric W. Biederman" <ebiederm@xmission•com>,
Linux Netdev List <netdev@vger•kernel.org>,
Ben Hutchings <bhutchings@solarflare•com>
Subject: [PATCH 4/5] net: Make ifindex generation per-net namespace
Date: Thu, 09 Aug 2012 11:53:19 +0400 [thread overview]
Message-ID: <50236C6F.10503@parallels.com> (raw)
In-Reply-To: <50236C20.4050108@parallels.com>
Strictly speaking this is only _really_ required for checkpoint-restore to
make loopback device always have the same index.
This change appears to be safe wrt "ifindex should be unique per-system"
concept, as all the ifindex usage is either already made per net namespace
of is explicitly limited with init_net only.
There are two cool side effects of this. The first one -- ifindices of
devices in container are always small, regardless of how many containers
we've started (and re-started) so far. The second one is -- we can speed
up the loopback ifidex access as shown in the next patch.
v2: Place ifindex right after dev_base_seq : avoid two holes and use the
same cache line, dirtied in list_netdevice()/unlist_netdevice()
Signed-off-by: Pavel Emelyanov <xemul@parallels•com>
Acked-by: Eric Dumazet <edumazet@google•com>
---
include/net/net_namespace.h | 1 +
net/core/dev.c | 4 ++--
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index ae1cd6c..6dc3db3 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -66,6 +66,7 @@ struct net {
struct hlist_head *dev_name_head;
struct hlist_head *dev_index_head;
unsigned int dev_base_seq; /* protected by rtnl_mutex */
+ int ifindex;
/* core fib_rules */
struct list_head rules_ops;
diff --git a/net/core/dev.c b/net/core/dev.c
index 3ca300d..1f06df8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5221,12 +5221,12 @@ int dev_ioctl(struct net *net, unsigned int cmd, void __user *arg)
*/
static int dev_new_index(struct net *net)
{
- static int ifindex;
+ int ifindex = net->ifindex;
for (;;) {
if (++ifindex <= 0)
ifindex = 1;
if (!__dev_get_by_index(net, ifindex))
- return ifindex;
+ return net->ifindex = ifindex;
}
}
--
1.7.6.5
next prev parent reply other threads:[~2012-08-09 7:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-09 7:52 [PATCH net-next 0/5] Per-net and on-demand link indices (and related) v3 Pavel Emelyanov
2012-08-09 7:52 ` [PATCH 1/5] net: Dont use ifindices in hash fns Pavel Emelyanov
2012-08-09 7:52 ` [PATCH 2/5] net: Allow to create links with given ifindex Pavel Emelyanov
2012-08-09 7:53 ` [PATCH 3/5] veth: Allow to create peer link " Pavel Emelyanov
2012-08-09 7:53 ` Pavel Emelyanov [this message]
2012-08-09 7:53 ` [PATCH 5/5] net: Loopback ifindex is constant now Pavel Emelyanov
2012-08-09 23:18 ` [PATCH net-next 0/5] Per-net and on-demand link indices (and related) v3 David Miller
-- strict thread matches above, loose matches on Subject: below --
2012-08-06 10:30 [PATCH net-next 0/5] Per-net and on-demand link indices (and related) Pavel Emelyanov
2012-08-06 10:31 ` [PATCH 4/5] net: Make ifindex generation per-net namespace Pavel Emelyanov
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=50236C6F.10503@parallels.com \
--to=xemul@parallels$(echo .)com \
--cc=bhutchings@solarflare$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=ebiederm@xmission$(echo .)com \
--cc=eric.dumazet@gmail$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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