Commit 44345724 authored by Octavian Purdila's avatar Octavian Purdila Committed by David S. Miller

net: factorize sync-rcu call in unregister_netdevice_many

Add dev_close_many and dev_deactivate_many to factorize another
sync-rcu operation on the netdevice unregister path.

$ modprobe dummy numdummies=10000
$ ip link set dev dummy* up
$ time rmmod dummy

Without the patch           With the patch

real    0m 24.63s           real    0m 5.15s
user    0m 0.00s            user    0m 0.00s
sys     0m 6.05s            sys     0m 5.14s
Signed-off-by: default avatarOctavian Purdila <opurdila@ixiacom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c6c8fea2
......@@ -321,6 +321,7 @@ extern void dev_init_scheduler(struct net_device *dev);
extern void dev_shutdown(struct net_device *dev);
extern void dev_activate(struct net_device *dev);
extern void dev_deactivate(struct net_device *dev);
extern void dev_deactivate_many(struct list_head *head);
extern struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
struct Qdisc *qdisc);
extern void qdisc_reset(struct Qdisc *qdisc);
......
......@@ -1222,13 +1222,14 @@ int dev_open(struct net_device *dev)
}
EXPORT_SYMBOL(dev_open);
static int __dev_close(struct net_device *dev)
static int __dev_close_many(struct list_head *head)
{
const struct net_device_ops *ops = dev->netdev_ops;
struct net_device *dev;
ASSERT_RTNL();
might_sleep();
list_for_each_entry(dev, head, unreg_list) {
/*
* Tell people we are going down, so that they can
* prepare to death, when device is still operating.
......@@ -1237,15 +1238,19 @@ static int __dev_close(struct net_device *dev)
clear_bit(__LINK_STATE_START, &dev->state);
/* Synchronize to scheduled poll. We cannot touch poll list,
* it can be even on different cpu. So just clear netif_running().
/* Synchronize to scheduled poll. We cannot touch poll list, it
* can be even on different cpu. So just clear netif_running().
*
* dev->stop() will invoke napi_disable() on all of it's
* napi_struct instances on this device.
*/
smp_mb__after_clear_bit(); /* Commit netif_running(). */
}
dev_deactivate_many(head);
dev_deactivate(dev);
list_for_each_entry(dev, head, unreg_list) {
const struct net_device_ops *ops = dev->netdev_ops;
/*
* Call the device specific close. This cannot fail.
......@@ -1267,7 +1272,40 @@ static int __dev_close(struct net_device *dev)
* Shutdown NET_DMA
*/
net_dmaengine_put();
}
return 0;
}
static int __dev_close(struct net_device *dev)
{
LIST_HEAD(single);
list_add(&dev->unreg_list, &single);
return __dev_close_many(&single);
}
int dev_close_many(struct list_head *head)
{
struct net_device *dev, *tmp;
LIST_HEAD(tmp_list);
list_for_each_entry_safe(dev, tmp, head, unreg_list)
if (!(dev->flags & IFF_UP))
list_move(&dev->unreg_list, &tmp_list);
__dev_close_many(head);
/*
* Tell people we are down
*/
list_for_each_entry(dev, head, unreg_list) {
rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
call_netdevice_notifiers(NETDEV_DOWN, dev);
}
/* rollback_registered_many needs the complete original list */
list_splice(&tmp_list, head);
return 0;
}
......@@ -1282,16 +1320,10 @@ static int __dev_close(struct net_device *dev)
*/
int dev_close(struct net_device *dev)
{
if (!(dev->flags & IFF_UP))
return 0;
__dev_close(dev);
LIST_HEAD(single);
/*
* Tell people we are down
*/
rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
call_netdevice_notifiers(NETDEV_DOWN, dev);
list_add(&dev->unreg_list, &single);
dev_close_many(&single);
return 0;
}
......@@ -4963,10 +4995,12 @@ static void rollback_registered_many(struct list_head *head)
}
BUG_ON(dev->reg_state != NETREG_REGISTERED);
}
/* If device is running, close it first. */
dev_close(dev);
dev_close_many(head);
list_for_each_entry(dev, head, unreg_list) {
/* And unlink it from device chain. */
unlist_netdevice(dev);
......
......@@ -810,22 +810,37 @@ static bool some_qdisc_is_busy(struct net_device *dev)
return false;
}
void dev_deactivate(struct net_device *dev)
void dev_deactivate_many(struct list_head *head)
{
netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
struct net_device *dev;
list_for_each_entry(dev, head, unreg_list) {
netdev_for_each_tx_queue(dev, dev_deactivate_queue,
&noop_qdisc);
if (dev_ingress_queue(dev))
dev_deactivate_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
dev_deactivate_queue(dev, dev_ingress_queue(dev),
&noop_qdisc);
dev_watchdog_down(dev);
}
/* Wait for outstanding qdisc-less dev_queue_xmit calls. */
synchronize_rcu();
/* Wait for outstanding qdisc_run calls. */
list_for_each_entry(dev, head, unreg_list)
while (some_qdisc_is_busy(dev))
yield();
}
void dev_deactivate(struct net_device *dev)
{
LIST_HEAD(single);
list_add(&dev->unreg_list, &single);
dev_deactivate_many(&single);
}
static void dev_init_scheduler_queue(struct net_device *dev,
struct netdev_queue *dev_queue,
void *_qdisc)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment