From: ebiederm@xmission•com (Eric W. Biederman)
To: Francesco Ruggeri <fruggeri@aristanetworks•com>
Cc: "David S. Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>, Jiri Pirko <jiri@resnulli•us>,
Alexander Duyck <alexander.h.duyck@intel•com>,
Cong Wang <amwang@redhat•com>,
netdev@vger•kernel.org
Subject: [CFT][PATCH] net: Delay default_device_exit_batch until no devices are unregistering
Date: Mon, 16 Sep 2013 20:49:31 -0700 [thread overview]
Message-ID: <87mwncaz04.fsf_-_@xmission.com> (raw)
In-Reply-To: <CA+HUmGih9akzhpRrb_0WEapi4jGcuSV8qO==QeRWHoqnxzFyng@mail.gmail.com> (Francesco Ruggeri's message of "Mon, 16 Sep 2013 13:30:50 -0700")
The implementation is a little rough but the logic should be right.
Device registration and unregistration is serialized with the rtnl_lock.
The final pieces of device unregistration do not happen under the
rtnl_lock resulting in the possibility that while we wait for the
refcount of a device to drop to zero the network namespace is
unregistered while no locks are held.
Prevent that by keeping a count of the network devices that are being
unregistered and before we make the final pass through a network
namespace to flush out all of the network devices, wait for the count of
network devices being unregistered to drop to zero.
Reported-by: Francesco Ruggeri <fruggeri@aristanetworks•com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission•com>
---
Francesco could you take a look at this. I am about 99% certain this is
right but I am starting to fade. So it is entirely possible I missed
something.
net/core/dev.c | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 5d702fe..c25e6f3 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5002,10 +5002,13 @@ static int dev_new_index(struct net *net)
/* Delayed registration/unregisteration */
static LIST_HEAD(net_todo_list);
+static atomic_t netdev_unregistering = ATOMIC_INIT(0);
+static DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wait);
static void net_set_todo(struct net_device *dev)
{
list_add_tail(&dev->todo_list, &net_todo_list);
+ atomic_inc(&netdev_unregistering);
}
static void rollback_registered_many(struct list_head *head)
@@ -5673,6 +5676,9 @@ void netdev_run_todo(void)
if (dev->destructor)
dev->destructor(dev);
+ if (atomic_dec_and_test(&netdev_unregistering))
+ wake_up(&netdev_unregistering_wait);
+
/* Free network device */
kobject_put(&dev->dev.kobj);
}
@@ -6369,7 +6375,13 @@ static void __net_exit default_device_exit_batch(struct list_head *net_list)
struct net *net;
LIST_HEAD(dev_kill_list);
+retry:
+ wait_event(netdev_unregistering_wait, (atomic_read(&netdev_unregistering) == 0));
rtnl_lock();
+ if (atomic_read(&netdev_unregistering) != 0) {
+ __rtnl_unlock();
+ goto retry;
+ }
list_for_each_entry(net, net_list, exit_list) {
for_each_netdev_reverse(net, dev) {
if (dev->rtnl_link_ops)
--
1.7.5.4
next prev parent reply other threads:[~2013-09-17 5:10 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1379008796-2121-1-git-send-email-fruggeri@aristanetworks.com>
2013-09-12 20:06 ` [PATCH 1/1] net: race condition when removing virtual net_device Eric W. Biederman
2013-09-12 21:48 ` Francesco Ruggeri
2013-09-12 22:02 ` Francesco Ruggeri
2013-09-13 5:50 ` Eric W. Biederman
2013-09-13 17:54 ` Francesco Ruggeri
2013-09-14 1:46 ` Eric W. Biederman
2013-09-16 2:54 ` Francesco Ruggeri
2013-09-16 10:45 ` Eric W. Biederman
2013-09-16 20:30 ` Francesco Ruggeri
2013-09-16 23:52 ` [PATCH net-next] net loopback: Set loopback_dev to NULL when freed Eric W. Biederman
2013-09-17 0:50 ` Eric Dumazet
2013-09-17 1:34 ` David Miller
2013-09-17 1:41 ` Eric Dumazet
2013-09-17 1:52 ` Eric W. Biederman
2013-09-17 23:05 ` David Miller
2013-09-17 0:25 ` [PATCH 1/1] net: race condition when removing virtual net_device Eric W. Biederman
2013-09-17 5:12 ` Francesco Ruggeri
2013-09-17 3:49 ` Eric W. Biederman [this message]
2013-09-17 6:54 ` [CFT][PATCH] net: Delay default_device_exit_batch until no devices are unregistering Francesco Ruggeri
2013-09-17 9:38 ` Eric W. Biederman
2013-09-17 17:14 ` Francesco Ruggeri
2013-09-17 23:21 ` David Miller
2013-09-17 23:41 ` Eric W. Biederman
2013-09-18 0:15 ` David Miller
2013-09-18 3:50 ` Francesco Ruggeri
2013-09-18 3:52 ` David Miller
2013-09-18 8:19 ` Eric W. Biederman
2013-09-20 16:34 ` Francesco Ruggeri
2013-09-24 4:19 ` [PATCH] net: Delay default_device_exit_batch until no devices are unregistering v2 Eric W. Biederman
2013-09-24 17:54 ` Francesco Ruggeri
2013-09-28 22:14 ` David Miller
2013-09-14 0:16 ` [PATCH 1/1] net: race condition when removing virtual net_device David Miller
2013-09-14 1:32 ` Eric W. Biederman
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