From: Jakub Kicinski kuba@kernel.org
net-next inclusion from net-next-v5.17-rc5 commit faab39f63c1fc4bcdf135690f03bd596b578c67e category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4VZN0?from=project-issue
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?...
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Sprinkle for each loops to allow netdevices to be unregistered out of order, as their refs are released.
This prevents problems caused by dependencies between netdevs which want to release references in their ->priv_destructor. See commit d6ff94afd90b ("vlan: move dev_put into vlan_dev_uninit") for example.
Eric has removed the only known ordering requirement in commit c002496babfd ("Merge branch 'ipv6-loopback'") so let's try this and see if anything explodes...
Reviewed-by: Eric Dumazet edumazet@google.com Reviewed-by: Xin Long lucien.xin@gmail.com Link: https://lore.kernel.org/r/20220215225310.3679266-2-kuba@kernel.org Signed-off-by: Jakub Kicinski kuba@kernel.org Conflicts: net/core/dev.c Signed-off-by: Ziyang Xuan william.xuanziyang@huawei.com Reviewed-by: Wei Yongjun weiyongjun1@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- net/core/dev.c | 59 +++++++++++++++++++++++++++++--------------------- 1 file changed, 34 insertions(+), 25 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c index 2c2fd376306c..d035234ce00f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10244,8 +10244,8 @@ EXPORT_SYMBOL(netdev_refcnt_read); #define WAIT_REFS_MIN_MSECS 1 #define WAIT_REFS_MAX_MSECS 250 /** - * netdev_wait_allrefs - wait until all references are gone. - * @dev: target net_device + * netdev_wait_allrefs_any - wait until all references are gone. + * @list: list of net_devices to wait on * * This is called when unregistering network devices. * @@ -10255,37 +10255,45 @@ EXPORT_SYMBOL(netdev_refcnt_read); * We can get stuck here if buggy protocols don't correctly * call dev_put. */ -static void netdev_wait_allrefs(struct net_device *dev) +static struct net_device *netdev_wait_allrefs_any(struct list_head *list) { unsigned long rebroadcast_time, warning_time; - int wait = 0, refcnt; + struct net_device *dev; + int wait = 0;
- linkwatch_forget_dev(dev); + list_for_each_entry(dev, list, todo_list) + linkwatch_forget_dev(dev);
rebroadcast_time = warning_time = jiffies; - refcnt = netdev_refcnt_read(dev);
- while (refcnt != 0) { + list_for_each_entry(dev, list, todo_list) + if (netdev_refcnt_read(dev) == 0) + return dev; + + while (true) { if (time_after(jiffies, rebroadcast_time + 1 * HZ)) { rtnl_lock();
/* Rebroadcast unregister notification */ - call_netdevice_notifiers(NETDEV_UNREGISTER, dev); + list_for_each_entry(dev, list, todo_list) + call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
__rtnl_unlock(); rcu_barrier(); rtnl_lock();
- if (test_bit(__LINK_STATE_LINKWATCH_PENDING, - &dev->state)) { - /* We must not have linkwatch events - * pending on unregister. If this - * happens, we simply run the queue - * unscheduled, resulting in a noop - * for this device. - */ - linkwatch_run_queue(); - } + list_for_each_entry(dev, list, todo_list) + if (test_bit(__LINK_STATE_LINKWATCH_PENDING, + &dev->state)) { + /* We must not have linkwatch events + * pending on unregister. If this + * happens, we simply run the queue + * unscheduled, resulting in a noop + * for this device. + */ + linkwatch_run_queue(); + break; + }
__rtnl_unlock();
@@ -10300,11 +10308,14 @@ static void netdev_wait_allrefs(struct net_device *dev) wait = min(wait << 1, WAIT_REFS_MAX_MSECS); }
- refcnt = netdev_refcnt_read(dev); + list_for_each_entry(dev, list, todo_list) + if (netdev_refcnt_read(dev) == 0) + return dev;
- if (refcnt && time_after(jiffies, warning_time + 10 * HZ)) { - pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n", - dev->name, refcnt); + if (time_after(jiffies, warning_time + 10 * HZ)) { + list_for_each_entry(dev, list, todo_list) + pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n", + dev->name, netdev_refcnt_read(dev)); warning_time = jiffies; } } @@ -10372,11 +10383,9 @@ void netdev_run_todo(void) }
while (!list_empty(&list)) { - dev = list_first_entry(&list, struct net_device, todo_list); + dev = netdev_wait_allrefs_any(&list); list_del(&dev->todo_list);
- netdev_wait_allrefs(dev); - /* paranoia */ BUG_ON(netdev_refcnt_read(dev)); BUG_ON(!list_empty(&dev->ptype_all));