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Diffstat (limited to 'net/sched/sch_generic.c')
-rw-r--r--net/sched/sch_generic.c219
1 files changed, 115 insertions, 104 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index f4d34480a09..c81649cf0b9 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -11,27 +11,19 @@
* - Ingress support
*/
-#include <asm/uaccess.h>
-#include <asm/system.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
-#include <linux/mm.h>
-#include <linux/socket.h>
-#include <linux/sockios.h>
-#include <linux/in.h>
#include <linux/errno.h>
-#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/rcupdate.h>
#include <linux/list.h>
-#include <net/sock.h>
#include <net/pkt_sched.h>
/* Main transmission queue. */
@@ -59,122 +51,143 @@ void qdisc_unlock_tree(struct net_device *dev)
spin_unlock_bh(&dev->queue_lock);
}
-/*
- dev->queue_lock serializes queue accesses for this device
- AND dev->qdisc pointer itself.
+static inline int qdisc_qlen(struct Qdisc *q)
+{
+ return q->q.qlen;
+}
- netif_tx_lock serializes accesses to device driver.
+static inline int dev_requeue_skb(struct sk_buff *skb, struct net_device *dev,
+ struct Qdisc *q)
+{
+ if (unlikely(skb->next))
+ dev->gso_skb = skb;
+ else
+ q->ops->requeue(skb, q);
- dev->queue_lock and netif_tx_lock are mutually exclusive,
- if one is grabbed, another must be free.
- */
+ netif_schedule(dev);
+ return 0;
+}
+static inline struct sk_buff *dev_dequeue_skb(struct net_device *dev,
+ struct Qdisc *q)
+{
+ struct sk_buff *skb;
-/* Kick device.
+ if ((skb = dev->gso_skb))
+ dev->gso_skb = NULL;
+ else
+ skb = q->dequeue(q);
- Returns: 0 - queue is empty or throttled.
- >0 - queue is not empty.
+ return skb;
+}
- NOTE: Called under dev->queue_lock with locally disabled BH.
-*/
+static inline int handle_dev_cpu_collision(struct sk_buff *skb,
+ struct net_device *dev,
+ struct Qdisc *q)
+{
+ int ret;
+ if (unlikely(dev->xmit_lock_owner == smp_processor_id())) {
+ /*
+ * Same CPU holding the lock. It may be a transient
+ * configuration error, when hard_start_xmit() recurses. We
+ * detect it by checking xmit owner and drop the packet when
+ * deadloop is detected. Return OK to try the next skb.
+ */
+ kfree_skb(skb);
+ if (net_ratelimit())
+ printk(KERN_WARNING "Dead loop on netdevice %s, "
+ "fix it urgently!\n", dev->name);
+ ret = qdisc_qlen(q);
+ } else {
+ /*
+ * Another cpu is holding lock, requeue & delay xmits for
+ * some time.
+ */
+ __get_cpu_var(netdev_rx_stat).cpu_collision++;
+ ret = dev_requeue_skb(skb, dev, q);
+ }
+
+ return ret;
+}
+
+/*
+ * NOTE: Called under dev->queue_lock with locally disabled BH.
+ *
+ * __LINK_STATE_QDISC_RUNNING guarantees only one CPU can process this
+ * device at a time. dev->queue_lock serializes queue accesses for
+ * this device AND dev->qdisc pointer itself.
+ *
+ * netif_tx_lock serializes accesses to device driver.
+ *
+ * dev->queue_lock and netif_tx_lock are mutually exclusive,
+ * if one is grabbed, another must be free.
+ *
+ * Note, that this procedure can be called by a watchdog timer
+ *
+ * Returns to the caller:
+ * 0 - queue is empty or throttled.
+ * >0 - queue is not empty.
+ *
+ */
static inline int qdisc_restart(struct net_device *dev)
{
struct Qdisc *q = dev->qdisc;
struct sk_buff *skb;
+ unsigned lockless;
+ int ret;
/* Dequeue packet */
- if (((skb = dev->gso_skb)) || ((skb = q->dequeue(q)))) {
- unsigned nolock = (dev->features & NETIF_F_LLTX);
+ if (unlikely((skb = dev_dequeue_skb(dev, q)) == NULL))
+ return 0;
+
+ /*
+ * When the driver has LLTX set, it does its own locking in
+ * start_xmit. These checks are worth it because even uncongested
+ * locks can be quite expensive. The driver can do a trylock, as
+ * is being done here; in case of lock contention it should return
+ * NETDEV_TX_LOCKED and the packet will be requeued.
+ */
+ lockless = (dev->features & NETIF_F_LLTX);
- dev->gso_skb = NULL;
+ if (!lockless && !netif_tx_trylock(dev)) {
+ /* Another CPU grabbed the driver tx lock */
+ return handle_dev_cpu_collision(skb, dev, q);
+ }
- /*
- * When the driver has LLTX set it does its own locking
- * in start_xmit. No need to add additional overhead by
- * locking again. These checks are worth it because
- * even uncongested locks can be quite expensive.
- * The driver can do trylock like here too, in case
- * of lock congestion it should return -1 and the packet
- * will be requeued.
- */
- if (!nolock) {
- if (!netif_tx_trylock(dev)) {
- collision:
- /* So, someone grabbed the driver. */
-
- /* It may be transient configuration error,
- when hard_start_xmit() recurses. We detect
- it by checking xmit owner and drop the
- packet when deadloop is detected.
- */
- if (dev->xmit_lock_owner == smp_processor_id()) {
- kfree_skb(skb);
- if (net_ratelimit())
- printk(KERN_DEBUG "Dead loop on netdevice %s, fix it urgently!\n", dev->name);
- goto out;
- }
- __get_cpu_var(netdev_rx_stat).cpu_collision++;
- goto requeue;
- }
- }
+ /* And release queue */
+ spin_unlock(&dev->queue_lock);
- {
- /* And release queue */
- spin_unlock(&dev->queue_lock);
-
- if (!netif_queue_stopped(dev)) {
- int ret;
-
- ret = dev_hard_start_xmit(skb, dev);
- if (ret == NETDEV_TX_OK) {
- if (!nolock) {
- netif_tx_unlock(dev);
- }
- spin_lock(&dev->queue_lock);
- q = dev->qdisc;
- goto out;
- }
- if (ret == NETDEV_TX_LOCKED && nolock) {
- spin_lock(&dev->queue_lock);
- q = dev->qdisc;
- goto collision;
- }
- }
+ ret = dev_hard_start_xmit(skb, dev);
- /* NETDEV_TX_BUSY - we need to requeue */
- /* Release the driver */
- if (!nolock) {
- netif_tx_unlock(dev);
- }
- spin_lock(&dev->queue_lock);
- q = dev->qdisc;
- }
+ if (!lockless)
+ netif_tx_unlock(dev);
- /* Device kicked us out :(
- This is possible in three cases:
+ spin_lock(&dev->queue_lock);
+ q = dev->qdisc;
- 0. driver is locked
- 1. fastroute is enabled
- 2. device cannot determine busy state
- before start of transmission (f.e. dialout)
- 3. device is buggy (ppp)
- */
+ switch (ret) {
+ case NETDEV_TX_OK:
+ /* Driver sent out skb successfully */
+ ret = qdisc_qlen(q);
+ break;
-requeue:
- if (unlikely(q == &noop_qdisc))
- kfree_skb(skb);
- else if (skb->next)
- dev->gso_skb = skb;
- else
- q->ops->requeue(skb, q);
- netif_schedule(dev);
+ case NETDEV_TX_LOCKED:
+ /* Driver try lock failed */
+ ret = handle_dev_cpu_collision(skb, dev, q);
+ break;
+
+ default:
+ /* Driver returned NETDEV_TX_BUSY - requeue skb */
+ if (unlikely (ret != NETDEV_TX_BUSY && net_ratelimit()))
+ printk(KERN_WARNING "BUG %s code %d qlen %d\n",
+ dev->name, ret, q->q.qlen);
+
+ ret = dev_requeue_skb(skb, dev, q);
+ break;
}
- return 0;
-out:
- BUG_ON((int) q->q.qlen < 0);
- return q->q.qlen;
+ return ret;
}
void __qdisc_run(struct net_device *dev)
@@ -493,9 +506,7 @@ void qdisc_destroy(struct Qdisc *qdisc)
return;
list_del(&qdisc->list);
-#ifdef CONFIG_NET_ESTIMATOR
gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);
-#endif
if (ops->reset)
ops->reset(qdisc);
if (ops->destroy)
generated by cgit v1.2.3 (git 2.25.1) at 2024-10-30 02:33:03 +0000