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authorYunsheng Lin <linyunsheng@huawei.com>2019-06-28 09:13:19 +0800
committerDavid S. Miller <davem@davemloft.net>2019-07-01 19:02:47 -0700
commit27ba4059e06b3bbd38a7d944fd5a78cdf47534f4 (patch)
tree717af81b11215303a6c0a7d5fbfeee53284e1825 /net
parent0d0bcacc54e65540b8a3d680c130b741010e23a3 (diff)
downloadlinux-27ba4059e06b3bbd38a7d944fd5a78cdf47534f4.tar.bz2
net: link_watch: prevent starvation when processing linkwatch wq
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> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/link_watch.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/net/core/link_watch.c b/net/core/link_watch.c
index 04fdc9535772..f153e0601838 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);