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pkt_sched: fq: do not hold qdisc lock while allocating memory

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Resizing fq hash table allocates memory while holding qdisc spinlock,
with BH disabled.

This is definitely not good, as allocation might sleep.

We can drop the lock and get it when needed, we hold RTNL so no other
changes can happen at the same time.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: afe4fd0624 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-03-06 22:57:52 -08:00 • committed by David S. Miller
commit 2d8d40afd1
1 changed files with 15 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

21
net/sched/sch_fq.c
View file

@ -601,6 +601,7 @@ static int fq_resize(struct Qdisc *sch, u32 log)
{
struct fq_sched_data *q = qdisc_priv(sch);
struct rb_root *array;
void *old_fq_root;
u32 idx;
if (q->fq_root && log == q->fq_trees_log)
@ -615,13 +616,19 @@ static int fq_resize(struct Qdisc *sch, u32 log)
for (idx = 0; idx < (1U << log); idx++)
array[idx] = RB_ROOT;
if (q->fq_root) {
fq_rehash(q, q->fq_root, q->fq_trees_log, array, log);
fq_free(q->fq_root);
}
sch_tree_lock(sch);
old_fq_root = q->fq_root;
if (old_fq_root)
fq_rehash(q, old_fq_root, q->fq_trees_log, array, log);
q->fq_root = array;
q->fq_trees_log = log;
sch_tree_unlock(sch);
fq_free(old_fq_root);
return 0;
}
@ -697,9 +704,11 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt)
q->flow_refill_delay = usecs_to_jiffies(usecs_delay);
}
if (!err)
if (!err) {
sch_tree_unlock(sch);
err = fq_resize(sch, fq_log);
sch_tree_lock(sch);
}
while (sch->q.qlen > sch->limit) {
struct sk_buff *skb = fq_dequeue(sch);