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Date: Fri, 9 May 2014 10:47:33 -0700
From: Cong Wang <xiyou.wangcong@...il.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Cong Wang <xiyou.wangcong@...il.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Cong Wang <cwang@...pensource.com>
Subject: [Patch net] rtnetlink: call rtnl_lock_unregistering() in rtnl_link_unregister()
From: Cong Wang <cwang@...pensource.com>
commit 50624c934db18ab90 (net: Delay default_device_exit_batch until no
devices are unregistering) introduced rtnl_lock_unregistering() for
default_device_exit_batch(). Same race could happen we when rmmod a driver
which calls rtnl_link_unregister() as we call dev->destructor without rtnl
lock.
I know making rtnl_lock_unregistering() a macro is ugly, but I don't find
any less ugly way to fix it unless we duplicate the code. For long term,
I think we should clean up the mess of netdev_run_todo() and net namespce
exit code.
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: David S. Miller <davem@...emloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
Signed-off-by: Cong Wang <cwang@...pensource.com>
---
include/linux/rtnetlink.h | 31 +++++++++++++++++++++++++++++++
net/core/dev.c | 32 ++------------------------------
net/core/rtnetlink.c | 2 +-
3 files changed, 34 insertions(+), 31 deletions(-)
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 8e3e66a..e70218d 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -4,6 +4,7 @@
#include <linux/mutex.h>
#include <linux/netdevice.h>
+#include <linux/wait.h>
#include <uapi/linux/rtnetlink.h>
extern int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, u32 group, int echo);
@@ -22,6 +23,36 @@ extern void rtnl_lock(void);
extern void rtnl_unlock(void);
extern int rtnl_trylock(void);
extern int rtnl_is_locked(void);
+
+extern wait_queue_head_t netdev_unregistering_wq;
+/* Return with the rtnl_lock held when there are no network
+ * devices unregistering in any network namespace in net_list.
+ */
+#define rtnl_lock_unregistering(net_list, member) \
+do { \
+ struct net *net; \
+ bool unregistering; \
+ DEFINE_WAIT(wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(&netdev_unregistering_wq, &wait, \
+ TASK_UNINTERRUPTIBLE); \
+ unregistering = false; \
+ rtnl_lock(); \
+ list_for_each_entry(net, net_list, member) { \
+ if (net->dev_unreg_count > 0) { \
+ unregistering = true; \
+ break; \
+ } \
+ } \
+ if (!unregistering) \
+ break; \
+ __rtnl_unlock(); \
+ schedule(); \
+ } \
+ finish_wait(&netdev_unregistering_wq, &wait); \
+} while (0)
+
#ifdef CONFIG_PROVE_LOCKING
extern int lockdep_rtnl_is_held(void);
#else
diff --git a/net/core/dev.c b/net/core/dev.c
index c619b86..25f7ed2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5541,7 +5541,7 @@ static int dev_new_index(struct net *net)
/* Delayed registration/unregisteration */
static LIST_HEAD(net_todo_list);
-static DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);
+DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);
static void net_set_todo(struct net_device *dev)
{
@@ -6926,34 +6926,6 @@ static void __net_exit default_device_exit(struct net *net)
rtnl_unlock();
}
-static void __net_exit rtnl_lock_unregistering(struct list_head *net_list)
-{
- /* Return with the rtnl_lock held when there are no network
- * devices unregistering in any network namespace in net_list.
- */
- struct net *net;
- bool unregistering;
- DEFINE_WAIT(wait);
-
- for (;;) {
- prepare_to_wait(&netdev_unregistering_wq, &wait,
- TASK_UNINTERRUPTIBLE);
- unregistering = false;
- rtnl_lock();
- list_for_each_entry(net, net_list, exit_list) {
- if (net->dev_unreg_count > 0) {
- unregistering = true;
- break;
- }
- }
- if (!unregistering)
- break;
- __rtnl_unlock();
- schedule();
- }
- finish_wait(&netdev_unregistering_wq, &wait);
-}
-
static void __net_exit default_device_exit_batch(struct list_head *net_list)
{
/* At exit all network devices most be removed from a network
@@ -6976,7 +6948,7 @@ static void __net_exit default_device_exit_batch(struct list_head *net_list)
* will run in the rtnl_unlock() at the end of
* default_device_exit_batch.
*/
- rtnl_lock_unregistering(net_list);
+ rtnl_lock_unregistering(net_list, exit_list);
list_for_each_entry(net, net_list, exit_list) {
for_each_netdev_reverse(net, dev) {
if (dev->rtnl_link_ops)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 9837beb..fd33a83 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -359,7 +359,7 @@ EXPORT_SYMBOL_GPL(__rtnl_link_unregister);
*/
void rtnl_link_unregister(struct rtnl_link_ops *ops)
{
- rtnl_lock();
+ rtnl_lock_unregistering(&net_namespace_list, list);
__rtnl_link_unregister(ops);
rtnl_unlock();
}
--
1.8.3.1
--
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