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Date: Mon, 13 Dec 2010 16:18:23 +0200
From: Octavian Purdila <opurdila@...acom.com>
To: netdev@...r.kernel.org
Cc: Lucian Adrian Grijincu <lucian.grijincu@...il.com>,
Vlad Dogaru <ddvlad@...edu.org>,
Octavian Purdila <opurdila@...acom.com>
Subject: [PATCH net-next-2.6] net: add dev_close_many
Add dev_close_many and dev_deactivate_many to factorize another
expensive sync-rcu operation in 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: Octavian Purdila <opurdila@...acom.com>
---
include/net/sch_generic.h | 1 +
net/core/dev.c | 121 ++++++++++++++++++++++++++++----------------
net/sched/sch_generic.c | 29 ++++++++---
3 files changed, 100 insertions(+), 51 deletions(-)
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index ea1f8a8..786cc39 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -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);
diff --git a/net/core/dev.c b/net/core/dev.c
index d28b3a0..7cab19f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1222,51 +1222,88 @@ 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) {
+ ASSERT_RTNL();
+ might_sleep();
- /*
- * Tell people we are going down, so that they can
- * prepare to death, when device is still operating.
- */
- call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
+ /*
+ * Tell people we are going down, so that they can
+ * prepare to death, when device is still operating.
+ */
+ call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
- clear_bit(__LINK_STATE_START, &dev->state);
+ 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().
- *
- * 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(). */
+ /* 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(dev);
+ dev_deactivate_many(head);
- /*
- * Call the device specific close. This cannot fail.
- * Only if device is UP
- *
- * We allow it to be called even after a DETACH hot-plug
- * event.
- */
- if (ops->ndo_stop)
- ops->ndo_stop(dev);
+ list_for_each_entry(dev, head, unreg_list) {
+ const struct net_device_ops *ops = dev->netdev_ops;
- /*
- * Device is now down.
- */
+ /*
+ * Call the device specific close. This cannot fail.
+ * Only if device is UP
+ *
+ * We allow it to be called even after a DETACH hot-plug
+ * event.
+ */
+ if (ops->ndo_stop)
+ ops->ndo_stop(dev);
+
+ /*
+ * Device is now down.
+ */
+
+ dev->flags &= ~IFF_UP;
+
+ /*
+ * Shutdown NET_DMA
+ */
+ net_dmaengine_put();
+ }
- dev->flags &= ~IFF_UP;
+ 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_for_each_entry_safe(dev, tmp, head, unreg_list)
+ if (!(dev->flags & IFF_UP)) {
+ list_del(&dev->unreg_list);
+ continue;
+ }
+
+ __dev_close_many(head);
/*
- * Shutdown NET_DMA
+ * Tell people we are down
*/
- net_dmaengine_put();
+ list_for_each_entry(dev, head, unreg_list) {
+ rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
+ call_netdevice_notifiers(NETDEV_DOWN, dev);
+ }
return 0;
}
@@ -1282,16 +1319,10 @@ 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;
}
@@ -4958,10 +4989,12 @@ 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);
+ /* If device is running, close it first. */
+ dev_close_many(head);
+ list_for_each_entry(dev, head, unreg_list) {
/* And unlink it from device chain. */
unlist_netdevice(dev);
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 0918834..34dc598 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -810,20 +810,35 @@ 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);
- if (dev_ingress_queue(dev))
- dev_deactivate_queue(dev, dev_ingress_queue(dev), &noop_qdisc);
+ struct net_device *dev;
- dev_watchdog_down(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_watchdog_down(dev);
+ }
/* Wait for outstanding qdisc-less dev_queue_xmit calls. */
synchronize_rcu();
/* Wait for outstanding qdisc_run calls. */
- while (some_qdisc_is_busy(dev))
- yield();
+ 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,
--
1.7.1
--
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