From 443457242beb6716b43db4d62fe148eab5515505 Mon Sep 17 00:00:00 2001 From: Octavian Purdila Date: Mon, 13 Dec 2010 12:44:07 +0000 Subject: [PATCH] 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: Octavian Purdila Signed-off-by: David S. Miller --- include/net/sch_generic.h | 1 + net/core/dev.c | 118 ++++++++++++++++++++++++-------------- net/sched/sch_generic.c | 29 +++++++--- 3 files changed, 99 insertions(+), 49 deletions(-) diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index ea1f8a83160..786cc396cb4 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 7ac26d2b972..794b20de5d4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1222,52 +1222,90 @@ 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(); - /* - * 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); + 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. + */ + 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_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); /* - * 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); + } + /* 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); + /* 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 0918834ee4a..34dc598440a 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, -- 2.20.1