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netdev: Fix lockdep warnings in multiqueue configurations. 

When support for multiple TX queues were added, the
netif_tx_lock() routines we converted to iterate over
all TX queues and grab each queue's spinlock.

This causes heartburn for lockdep and it's not a healthy
thing to do with lots of TX queues anyways.

So modify this to use a top-level lock and a "frozen"
state for the individual TX queues.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2008-07-31 16:58:50 -07:00
parent 967ab999a0
commit c3f26a269c
7 changed files with 81 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/net/ifb.c
View File

@ -69,18 +69,20 @@ static void ri_tasklet(unsigned long dev)
struct net_device *_dev = (struct net_device *)dev;
struct ifb_private *dp = netdev_priv(_dev);
struct net_device_stats *stats = &_dev->stats;
struct netdev_queue *txq;
struct sk_buff *skb;
txq = netdev_get_tx_queue(_dev, 0);
dp->st_task_enter++;
if ((skb = skb_peek(&dp->tq)) == NULL) {
dp->st_txq_refl_try++;
if (netif_tx_trylock(_dev)) {
if (__netif_tx_trylock(txq)) {
dp->st_rxq_enter++;
while ((skb = skb_dequeue(&dp->rq)) != NULL) {
skb_queue_tail(&dp->tq, skb);
dp->st_rx2tx_tran++;
}
netif_tx_unlock(_dev);
__netif_tx_unlock(txq);
} else {
/* reschedule */
dp->st_rxq_notenter++;
@ -115,7 +117,7 @@ static void ri_tasklet(unsigned long dev)
BUG();
}
if (netif_tx_trylock(_dev)) {
if (__netif_tx_trylock(txq)) {
dp->st_rxq_check++;
if ((skb = skb_peek(&dp->rq)) == NULL) {
dp->tasklet_pending = 0;
@ -123,10 +125,10 @@ static void ri_tasklet(unsigned long dev)
netif_wake_queue(_dev);
} else {
dp->st_rxq_rsch++;
netif_tx_unlock(_dev);
__netif_tx_unlock(txq);
goto resched;
}
netif_tx_unlock(_dev);
__netif_tx_unlock(txq);
} else {
resched:
dp->tasklet_pending = 1;

92
include/linux/netdevice.h
View File

@ -440,6 +440,7 @@ static inline void napi_synchronize(const struct napi_struct *n)
enum netdev_queue_state_t
{
__QUEUE_STATE_XOFF,
__QUEUE_STATE_FROZEN,
};
struct netdev_queue {
@ -636,7 +637,7 @@ struct net_device
unsigned int real_num_tx_queues;
unsigned long tx_queue_len; /* Max frames per queue allowed */
spinlock_t tx_global_lock;
/*
* One part is mostly used on xmit path (device)
*/
@ -1099,6 +1100,11 @@ static inline int netif_queue_stopped(const struct net_device *dev)
return netif_tx_queue_stopped(netdev_get_tx_queue(dev, 0));
}
static inline int netif_tx_queue_frozen(const struct netdev_queue *dev_queue)
{
return test_bit(__QUEUE_STATE_FROZEN, &dev_queue->state);
}
/**
* netif_running - test if up
* @dev: network device
@ -1475,30 +1481,6 @@ static inline void __netif_tx_lock_bh(struct netdev_queue *txq)
txq->xmit_lock_owner = smp_processor_id();
}
/**
* netif_tx_lock - grab network device transmit lock
* @dev: network device
* @cpu: cpu number of lock owner
*
* Get network device transmit lock
*/
static inline void netif_tx_lock(struct net_device *dev)
{
int cpu = smp_processor_id();
unsigned int i;
for (i = 0; i < dev->num_tx_queues; i++) {
struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
__netif_tx_lock(txq, cpu);
}
}
static inline void netif_tx_lock_bh(struct net_device *dev)
{
local_bh_disable();
netif_tx_lock(dev);
}
static inline int __netif_tx_trylock(struct netdev_queue *txq)
{
int ok = spin_trylock(&txq->_xmit_lock);
@ -1507,11 +1489,6 @@ static inline int __netif_tx_trylock(struct netdev_queue *txq)
return ok;
}
static inline int netif_tx_trylock(struct net_device *dev)
{
return __netif_tx_trylock(netdev_get_tx_queue(dev, 0));
}
static inline void __netif_tx_unlock(struct netdev_queue *txq)
{
txq->xmit_lock_owner = -1;
@ -1524,15 +1501,57 @@ static inline void __netif_tx_unlock_bh(struct netdev_queue *txq)
spin_unlock_bh(&txq->_xmit_lock);
}
/**
* netif_tx_lock - grab network device transmit lock
* @dev: network device
* @cpu: cpu number of lock owner
*
* Get network device transmit lock
*/
static inline void netif_tx_lock(struct net_device *dev)
{
unsigned int i;
int cpu;
spin_lock(&dev->tx_global_lock);
cpu = smp_processor_id();
for (i = 0; i < dev->num_tx_queues; i++) {
struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
/* We are the only thread of execution doing a
* freeze, but we have to grab the _xmit_lock in
* order to synchronize with threads which are in
* the ->hard_start_xmit() handler and already
* checked the frozen bit.
*/
__netif_tx_lock(txq, cpu);
set_bit(__QUEUE_STATE_FROZEN, &txq->state);
__netif_tx_unlock(txq);
}
}
static inline void netif_tx_lock_bh(struct net_device *dev)
{
local_bh_disable();
netif_tx_lock(dev);
}
static inline void netif_tx_unlock(struct net_device *dev)
{
unsigned int i;
for (i = 0; i < dev->num_tx_queues; i++) {
struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
__netif_tx_unlock(txq);
}
/* No need to grab the _xmit_lock here. If the
* queue is not stopped for another reason, we
* force a schedule.
*/
clear_bit(__QUEUE_STATE_FROZEN, &txq->state);
if (!test_bit(__QUEUE_STATE_XOFF, &txq->state))
__netif_schedule(txq->qdisc);
}
spin_unlock(&dev->tx_global_lock);
}
static inline void netif_tx_unlock_bh(struct net_device *dev)
@ -1556,13 +1575,18 @@ static inline void netif_tx_unlock_bh(struct net_device *dev)
static inline void netif_tx_disable(struct net_device *dev)
{
unsigned int i;
int cpu;
netif_tx_lock_bh(dev);
local_bh_disable();
cpu = smp_processor_id();
for (i = 0; i < dev->num_tx_queues; i++) {
struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
__netif_tx_lock(txq, cpu);
netif_tx_stop_queue(txq);
__netif_tx_unlock(txq);
}
netif_tx_unlock_bh(dev);
local_bh_enable();
}
static inline void netif_addr_lock(struct net_device *dev)

1
net/core/dev.c
View File

@ -4200,6 +4200,7 @@ static void netdev_init_queues(struct net_device *dev)
{
netdev_init_one_queue(dev, &dev->rx_queue, NULL);
netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
spin_lock_init(&dev->tx_global_lock);
}
/**

1
net/core/netpoll.c
View File

@ -70,6 +70,7 @@ static void queue_process(struct work_struct *work)
local_irq_save(flags);
__netif_tx_lock(txq, smp_processor_id());
if (netif_tx_queue_stopped(txq) ||
netif_tx_queue_frozen(txq) ||
dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
skb_queue_head(&npinfo->txq, skb);
__netif_tx_unlock(txq);

7
net/core/pktgen.c
View File

@ -3305,6 +3305,7 @@ static __inline__ void pktgen_xmit(struct pktgen_dev *pkt_dev)
txq = netdev_get_tx_queue(odev, queue_map);
if (netif_tx_queue_stopped(txq) ||
netif_tx_queue_frozen(txq) ||
need_resched()) {
idle_start = getCurUs();
@ -3320,7 +3321,8 @@ static __inline__ void pktgen_xmit(struct pktgen_dev *pkt_dev)
pkt_dev->idle_acc += getCurUs() - idle_start;
if (netif_tx_queue_stopped(txq)) {
if (netif_tx_queue_stopped(txq) ||
netif_tx_queue_frozen(txq)) {
pkt_dev->next_tx_us = getCurUs(); /* TODO */
pkt_dev->next_tx_ns = 0;
goto out; /* Try the next interface */
@ -3352,7 +3354,8 @@ static __inline__ void pktgen_xmit(struct pktgen_dev *pkt_dev)
txq = netdev_get_tx_queue(odev, queue_map);
__netif_tx_lock_bh(txq);
if (!netif_tx_queue_stopped(txq)) {
if (!netif_tx_queue_stopped(txq) &&
!netif_tx_queue_frozen(txq)) {
atomic_inc(&(pkt_dev->skb->users));
retry_now:

6
net/sched/sch_generic.c
View File

@ -135,7 +135,8 @@ static inline int qdisc_restart(struct Qdisc *q)
txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
HARD_TX_LOCK(dev, txq, smp_processor_id());
if (!netif_subqueue_stopped(dev, skb))
if (!netif_tx_queue_stopped(txq) &&
!netif_tx_queue_frozen(txq))
ret = dev_hard_start_xmit(skb, dev, txq);
HARD_TX_UNLOCK(dev, txq);
@ -162,7 +163,8 @@ static inline int qdisc_restart(struct Qdisc *q)
break;
}
if (ret && netif_tx_queue_stopped(txq))
if (ret && (netif_tx_queue_stopped(txq) ||
netif_tx_queue_frozen(txq)))
ret = 0;
return ret;

9
net/sched/sch_teql.c
View File

@ -305,10 +305,11 @@ restart:
switch (teql_resolve(skb, skb_res, slave)) {
case 0:
if (netif_tx_trylock(slave)) {
if (!__netif_subqueue_stopped(slave, subq) &&
if (__netif_tx_trylock(slave_txq)) {
if (!netif_tx_queue_stopped(slave_txq) &&
!netif_tx_queue_frozen(slave_txq) &&
slave->hard_start_xmit(skb, slave) == 0) {
netif_tx_unlock(slave);
__netif_tx_unlock(slave_txq);
master->slaves = NEXT_SLAVE(q);
netif_wake_queue(dev);
master->stats.tx_packets++;
@ -316,7 +317,7 @@ restart:
qdisc_pkt_len(skb);
return 0;
}
netif_tx_unlock(slave);
__netif_tx_unlock(slave_txq);
}
if (netif_queue_stopped(dev))
busy = 1;