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authorJohn Fastabend <john.fastabend@gmail.com>2017-12-07 09:56:04 -0800
committerDavid S. Miller <davem@davemloft.net>2017-12-08 13:32:25 -0500
commit7bbde83b1860c28a1cc35516352c4e7e5172c29a (patch)
tree7561b35b1ac9ddcc6c3280ea74dc591656d72f10 /net/sched/sch_generic.c
parenta53851e2c3218aa30b77abd6e68cf1c371f15afe (diff)
downloadlinux-sh-7bbde83b1860c28a1cc35516352c4e7e5172c29a.tar.gz
net: sched: drop qdisc_reset from dev_graft_qdisc
In qdisc_graft_qdisc a "new" qdisc is attached and the 'qdisc_destroy' operation is called on the old qdisc. The destroy operation will wait a rcu grace period and call qdisc_rcu_free(). At which point gso_cpu_skb is free'd along with all stats so no need to zero stats and gso_cpu_skb from the graft operation itself. Further after dropping the qdisc locks we can not continue to call qdisc_reset before waiting an rcu grace period so that the qdisc is detached from all cpus. By removing the qdisc_reset() here we get the correct property of waiting an rcu grace period and letting the qdisc_destroy operation clean up the qdisc correctly. Note, a refcnt greater than 1 would cause the destroy operation to be aborted however if this ever happened the reference to the qdisc would be lost and we would have a memory leak. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_generic.c')
-rw-r--r--net/sched/sch_generic.c28
1 files changed, 19 insertions, 9 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index dfeabe319c56..482ba2234470 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -819,10 +819,6 @@ struct Qdisc *dev_graft_qdisc(struct netdev_queue *dev_queue,
root_lock = qdisc_lock(oqdisc);
spin_lock_bh(root_lock);
- /* Prune old scheduler */
- if (oqdisc && refcount_read(&oqdisc->refcnt) <= 1)
- qdisc_reset(oqdisc);
-
/* ... and graft new one */
if (qdisc == NULL)
qdisc = &noop_qdisc;
@@ -977,6 +973,16 @@ static bool some_qdisc_is_busy(struct net_device *dev)
return false;
}
+static void dev_qdisc_reset(struct net_device *dev,
+ struct netdev_queue *dev_queue,
+ void *none)
+{
+ struct Qdisc *qdisc = dev_queue->qdisc_sleeping;
+
+ if (qdisc)
+ qdisc_reset(qdisc);
+}
+
/**
* dev_deactivate_many - deactivate transmissions on several devices
* @head: list of devices to deactivate
@@ -987,7 +993,6 @@ static bool some_qdisc_is_busy(struct net_device *dev)
void dev_deactivate_many(struct list_head *head)
{
struct net_device *dev;
- bool sync_needed = false;
list_for_each_entry(dev, head, close_list) {
netdev_for_each_tx_queue(dev, dev_deactivate_queue,
@@ -997,20 +1002,25 @@ void dev_deactivate_many(struct list_head *head)
&noop_qdisc);
dev_watchdog_down(dev);
- sync_needed |= !dev->dismantle;
}
/* Wait for outstanding qdisc-less dev_queue_xmit calls.
* This is avoided if all devices are in dismantle phase :
* Caller will call synchronize_net() for us
*/
- if (sync_needed)
- synchronize_net();
+ synchronize_net();
/* Wait for outstanding qdisc_run calls. */
- list_for_each_entry(dev, head, close_list)
+ list_for_each_entry(dev, head, close_list) {
while (some_qdisc_is_busy(dev))
yield();
+ /* The new qdisc is assigned at this point so we can safely
+ * unwind stale skb lists and qdisc statistics
+ */
+ netdev_for_each_tx_queue(dev, dev_qdisc_reset, NULL);
+ if (dev_ingress_queue(dev))
+ dev_qdisc_reset(dev, dev_ingress_queue(dev), NULL);
+ }
}
void dev_deactivate(struct net_device *dev)