netem: dont call vfree() under spinlock and BH disabled

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>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index eb3b9a86c6ed..a4ab207cdc59 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -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;
 }