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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>
This commit is contained in:
David S. Miller 2008-08-02 20:02:43 -07:00
parent 82f97b8d3c
commit 5fb662297b
2 changed files with 8 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
net/core/dev.c
View File

@ -1796,7 +1796,7 @@ gso:
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 @@ static void net_tx_action(struct softirq_action *h)
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);

12
net/sched/sch_generic.c
View File

@ -29,7 +29,7 @@
/* Main transmission queue. */
/* Modifications to data participating in scheduling must be protected with
* qdisc_root_lock(qdisc) spinlock.
* qdisc_lock(qdisc) spinlock.
*
* The idea is the following:
* - enqueue, dequeue are serialized via qdisc root lock
@ -126,7 +126,7 @@ static inline int qdisc_restart(struct Qdisc *q)
if (unlikely((skb = dequeue_skb(q)) == NULL))
return 0;
root_lock = qdisc_root_lock(q);
root_lock = qdisc_lock(q);
/* And release qdisc */
spin_unlock(root_lock);
@ -507,7 +507,7 @@ errout:
}
EXPORT_SYMBOL(qdisc_create_dflt);
/* Under qdisc_root_lock(qdisc) and BH! */
/* Under qdisc_lock(qdisc) and BH! */
void qdisc_reset(struct Qdisc *qdisc)
{
@ -543,7 +543,7 @@ static void __qdisc_destroy(struct rcu_head *head)
kfree((char *) qdisc - qdisc->padded);
}
/* Under qdisc_root_lock(qdisc) and BH! */
/* Under qdisc_lock(qdisc) and BH! */
void qdisc_destroy(struct Qdisc *qdisc)
{
@ -659,7 +659,7 @@ static bool some_qdisc_is_running(struct net_device *dev, int lock)
dev_queue = netdev_get_tx_queue(dev, i);
q = dev_queue->qdisc;
root_lock = qdisc_root_lock(q);
root_lock = qdisc_lock(q);
if (lock)
spin_lock_bh(root_lock);
@ -735,7 +735,7 @@ static void shutdown_scheduler_queue(struct net_device *dev,
struct Qdisc *qdisc_default = _qdisc_default;
if (qdisc) {
spinlock_t *root_lock = qdisc_root_lock(qdisc);
spinlock_t *root_lock = qdisc_lock(qdisc);
dev_queue->qdisc = qdisc_default;
dev_queue->qdisc_sleeping = qdisc_default;