netem: dont call vfree() under spinlock and BH disabled
Eric Dumazet [Fri, 23 Dec 2011 19:28:51 +0000 (19:28 +0000)]
commit 6373a9a286 (netem: use vmalloc for distribution table) added a
regression, since vfree() is called while holding a spinlock and BH
being disabled.

Fix this by doing the pointers swap in critical section, and freeing
after spinlock release.

Also add __GFP_NOWARN to the kmalloc() try, since we fallback to
vmalloc().

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_netem.c

index eb3b9a8..a4ab207 100644 (file)
@@ -488,7 +488,7 @@ static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
                return -EINVAL;
 
        s = sizeof(struct disttable) + n * sizeof(s16);
-       d = kmalloc(s, GFP_KERNEL);
+       d = kmalloc(s, GFP_KERNEL | __GFP_NOWARN);
        if (!d)
                d = vmalloc(s);
        if (!d)
@@ -501,9 +501,10 @@ static int get_dist_table(struct Qdisc *sch, const struct nlattr *attr)
        root_lock = qdisc_root_sleeping_lock(sch);
 
        spin_lock_bh(root_lock);
-       dist_free(q->delay_dist);
-       q->delay_dist = d;
+       swap(q->delay_dist, d);
        spin_unlock_bh(root_lock);
+
+       dist_free(d);
        return 0;
 }