From c3f26a269c2421f97f10cf8ed05d5099b573af4d Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 31 Jul 2008 16:58:50 -0700 Subject: [PATCH] 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 --- drivers/net/ifb.c | 12 +++--- include/linux/netdevice.h | 86 +++++++++++++++++++++++++-------------- net/core/dev.c | 1 + net/core/netpoll.c | 1 + net/core/pktgen.c | 7 +++- net/sched/sch_generic.c | 6 ++- net/sched/sch_teql.c | 9 ++-- 7 files changed, 78 insertions(+), 44 deletions(-) diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c index 0960e69b2da4..e4fbefc8c82f 100644 --- a/drivers/net/ifb.c +++ b/drivers/net/ifb.c @@ -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; diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index b4d056ceab96..ee583f642a9f 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -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) diff --git a/net/core/dev.c b/net/core/dev.c index 63d6bcddbf46..69320a56a084 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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); } /** diff --git a/net/core/netpoll.c b/net/core/netpoll.c index c12720895ecf..6c7af390be0a 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -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); diff --git a/net/core/pktgen.c b/net/core/pktgen.c index c7d484f7e1c4..3284605f2ec7 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -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: diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 345838a2e369..9c9cd4d94890 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -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; diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c index 537223642b6e..2c35c678563b 100644 --- a/net/sched/sch_teql.c +++ b/net/sched/sch_teql.c @@ -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; -- 2.20.1