pkt_sched: Use qdisc_lock() on already sampled root qdisc.
Based upon a bug report by Jeff Kirsher.
Don't use qdisc_root_lock() in these cases as the root
qdisc could have been changed, and we'd thus lock the
wrong object.
Tested by Emil S Tantilov who confirms that this seems
to fix the problem.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 69320a5..da7acac 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1796,7 +1796,7 @@
skb->tc_verd = SET_TC_AT(skb->tc_verd,AT_EGRESS);
#endif
if (q->enqueue) {
- spinlock_t *root_lock = qdisc_root_lock(q);
+ spinlock_t *root_lock = qdisc_lock(q);
spin_lock(root_lock);
@@ -1995,7 +1995,7 @@
smp_mb__before_clear_bit();
clear_bit(__QDISC_STATE_SCHED, &q->state);
- root_lock = qdisc_root_lock(q);
+ root_lock = qdisc_lock(q);
if (spin_trylock(root_lock)) {
qdisc_run(q);
spin_unlock(root_lock);