From: David Vrabel Date: Wed, 2 Jul 2014 15:09:15 +0000 (+0100) Subject: xen-netfront: call netif_carrier_off() only once when disconnecting X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f9feb1e6a25f9e197f9e6e6cb04bf04d2cccff93;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git 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 --- diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 6a37d62de40b..055222bae6e4 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);