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Commit c3f26a26 authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parent 967ab999

drivers/net/ifb.c

+7 −5
Original line number Diff line number Diff line
@@ -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;

include/linux/netdevice.h

+55 −31
Original line number Diff line number Diff line
@@ -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
@@ -1475,6 +1481,26 @@ static inline void __netif_tx_lock_bh(struct netdev_queue *txq) 
	txq->xmit_lock_owner = smp_processor_id();

}



static inline int __netif_tx_trylock(struct netdev_queue *txq)

{

	int ok = spin_trylock(&txq->_xmit_lock);

	if (likely(ok))

		txq->xmit_lock_owner = smp_processor_id();

	return ok;

}



static inline void __netif_tx_unlock(struct netdev_queue *txq)

{

	txq->xmit_lock_owner = -1;

	spin_unlock(&txq->_xmit_lock);

}



static inline void __netif_tx_unlock_bh(struct netdev_queue *txq)

{

	txq->xmit_lock_owner = -1;

	spin_unlock_bh(&txq->_xmit_lock);

}



/**

 *	netif_tx_lock - grab network device transmit lock

 *	@dev: network device
@@ -1484,12 +1510,23 @@ static inline void __netif_tx_lock_bh(struct netdev_queue *txq) 
 */

static inline void netif_tx_lock(struct net_device *dev)

{

	int cpu = smp_processor_id();

	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);

	}

}
@@ -1499,40 +1536,22 @@ static inline void netif_tx_lock_bh(struct net_device *dev) 
	netif_tx_lock(dev);

}



static inline int __netif_tx_trylock(struct netdev_queue *txq)

{

	int ok = spin_trylock(&txq->_xmit_lock);

	if (likely(ok))

		txq->xmit_lock_owner = smp_processor_id();

	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;

	spin_unlock(&txq->_xmit_lock);

}



static inline void __netif_tx_unlock_bh(struct netdev_queue *txq)

{

	txq->xmit_lock_owner = -1;

	spin_unlock_bh(&txq->_xmit_lock);

}



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)

net/core/dev.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

}



/**

net/core/netpoll.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

net/core/pktgen.c

+5 −2
Original line number Diff line number Diff line
@@ -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: