| Message ID | 1561684399-235123-1-git-send-email-linyunsheng@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,net-next] net: link_watch: prevent starvation when processing linkwatch wq | expand |
From: Yunsheng Lin <linyunsheng@huawei.com> Date: Fri, 28 Jun 2019 09:13:19 +0800 > When user has configured a large number of virtual netdev, such > as 4K vlans, the carrier on/off operation of the real netdev > will also cause it's virtual netdev's link state to be processed > in linkwatch. Currently, the processing is done in a work queue, > which may cause rtnl locking starvation problem and worker > starvation problem for other work queue, such as irqfd_inject wq. > > This patch releases the cpu when link watch worker has processed > a fixed number of netdev' link watch event, and schedule the > work queue again when there is still link watch event remaining. > > Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> > --- > V2: use cond_resched and rtnl_unlock after processing a fixed > number of events > V3: fall back to v1 and change commit log to reflect that. Applied, thanks.
diff --git a/net/core/link_watch.c b/net/core/link_watch.c index 04fdc95..f153e06 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -163,9 +163,16 @@ static void linkwatch_do_dev(struct net_device *dev) static void __linkwatch_run_queue(int urgent_only) { +#define MAX_DO_DEV_PER_LOOP 100 + + int do_dev = MAX_DO_DEV_PER_LOOP; struct net_device *dev; LIST_HEAD(wrk); + /* Give urgent case more budget */ + if (urgent_only) + do_dev += MAX_DO_DEV_PER_LOOP; + /* * Limit the number of linkwatch events to one * per second so that a runaway driver does not @@ -184,7 +191,7 @@ static void __linkwatch_run_queue(int urgent_only) spin_lock_irq(&lweventlist_lock); list_splice_init(&lweventlist, &wrk); - while (!list_empty(&wrk)) { + while (!list_empty(&wrk) && do_dev > 0) { dev = list_first_entry(&wrk, struct net_device, link_watch_list); list_del_init(&dev->link_watch_list); @@ -195,9 +202,13 @@ static void __linkwatch_run_queue(int urgent_only) } spin_unlock_irq(&lweventlist_lock); linkwatch_do_dev(dev); + do_dev--; spin_lock_irq(&lweventlist_lock); } + /* Add the remaining work back to lweventlist */ + list_splice_init(&wrk, &lweventlist); + if (!list_empty(&lweventlist)) linkwatch_schedule_work(0); spin_unlock_irq(&lweventlist_lock);
When user has configured a large number of virtual netdev, such as 4K vlans, the carrier on/off operation of the real netdev will also cause it's virtual netdev's link state to be processed in linkwatch. Currently, the processing is done in a work queue, which may cause rtnl locking starvation problem and worker starvation problem for other work queue, such as irqfd_inject wq. This patch releases the cpu when link watch worker has processed a fixed number of netdev' link watch event, and schedule the work queue again when there is still link watch event remaining. Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> --- V2: use cond_resched and rtnl_unlock after processing a fixed number of events V3: fall back to v1 and change commit log to reflect that. --- --- net/core/link_watch.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)