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netdev: Fix lockdep warnings in multiqueue configurations.

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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
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92
include/linux/netdevice.h
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@@ -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)