From f9feb1e6a25f9e197f9e6e6cb04bf04d2cccff93 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 2 Jul 2014 16:09:15 +0100 Subject: [PATCH] xen-netfront: call netif_carrier_off() only once when disconnecting In xennet_disconnect_backend(), netif_carrier_off() was called once per queue when it needs to only be called once. The queue locking around the netif_carrier_off() call looked very odd. I think they were supposed to synchronize any NAPI instances with the expectation that no further NAPI instances would be scheduled because of the carrier being off (see the check in xennet_rx_interrupt()). But I can't easily tell if this works correctly. Instead, add a napi_synchronize() call after disabling the interrupts. This is obviously correct as with no Rx interrupts, no further NAPI instances will be scheduled. Signed-off-by: David Vrabel Signed-off-by: David S. Miller --- drivers/net/xen-netfront.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 6a37d62..055222b 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -1439,16 +1439,11 @@ static void xennet_disconnect_backend(struct netfront_info *info) unsigned int i = 0; unsigned int num_queues = info->netdev->real_num_tx_queues; + netif_carrier_off(info->netdev); + for (i = 0; i < num_queues; ++i) { struct netfront_queue *queue = &info->queues[i]; - /* Stop old i/f to prevent errors whilst we rebuild the state. */ - spin_lock_bh(&queue->rx_lock); - spin_lock_irq(&queue->tx_lock); - netif_carrier_off(queue->info->netdev); - spin_unlock_irq(&queue->tx_lock); - spin_unlock_bh(&queue->rx_lock); - if (queue->tx_irq && (queue->tx_irq == queue->rx_irq)) unbind_from_irqhandler(queue->tx_irq, queue); if (queue->tx_irq && (queue->tx_irq != queue->rx_irq)) { @@ -1458,6 +1453,8 @@ static void xennet_disconnect_backend(struct netfront_info *info) queue->tx_evtchn = queue->rx_evtchn = 0; queue->tx_irq = queue->rx_irq = 0; + napi_synchronize(&queue->napi); + /* End access and free the pages */ xennet_end_access(queue->tx_ring_ref, queue->tx.sring); xennet_end_access(queue->rx_ring_ref, queue->rx.sring); -- 2.7.4