diff options
| -rw-r--r-- | drivers/net/xen-netback/common.h | 15 | ||||
| -rw-r--r-- | drivers/net/xen-netback/interface.c | 49 | ||||
| -rw-r--r-- | drivers/net/xen-netback/netback.c | 97 |
3 files changed, 123 insertions, 38 deletions
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h index 4a92fc19f410..ef3026f46a37 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -176,9 +176,9 @@ struct xenvif_queue { /* Per-queue data for xenvif */ struct xen_netif_rx_back_ring rx; struct sk_buff_head rx_queue; RING_IDX rx_last_skb_slots; - bool rx_queue_purge; + unsigned long status; - struct timer_list wake_queue; + struct timer_list rx_stalled; struct gnttab_copy grant_copy_op[MAX_GRANT_COPY_OPS]; @@ -200,7 +200,16 @@ struct xenvif_queue { /* Per-queue data for xenvif */ enum state_bit_shift { /* This bit marks that the vif is connected */ - VIF_STATUS_CONNECTED + VIF_STATUS_CONNECTED, + /* This bit signals the RX thread that queuing was stopped (in + * start_xmit), and either the timer fired or an RX interrupt came + */ + QUEUE_STATUS_RX_PURGE_EVENT, + /* This bit tells the interrupt handler that this queue was the reason + * for the carrier off, so it should kick the thread. Only queues which + * brought it down can turn on the carrier. + */ + QUEUE_STATUS_RX_STALLED }; struct xenvif { diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index fbdadb3d8220..48a55cda979b 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -78,8 +78,12 @@ int xenvif_poll(struct napi_struct *napi, int budget) /* This vif is rogue, we pretend we've there is nothing to do * for this vif to deschedule it from NAPI. But this interface * will be turned off in thread context later. + * Also, if a guest doesn't post enough slots to receive data on one of + * its queues, the carrier goes down and NAPI is descheduled here so + * the guest can't send more packets until it's ready to receive. */ - if (unlikely(queue->vif->disabled)) { + if (unlikely(queue->vif->disabled || + !netif_carrier_ok(queue->vif->dev))) { napi_complete(napi); return 0; } @@ -97,7 +101,16 @@ int xenvif_poll(struct napi_struct *napi, int budget) static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id) { struct xenvif_queue *queue = dev_id; + struct netdev_queue *net_queue = + netdev_get_tx_queue(queue->vif->dev, queue->id); + /* QUEUE_STATUS_RX_PURGE_EVENT is only set if either QDisc was off OR + * the carrier went down and this queue was previously blocked + */ + if (unlikely(netif_tx_queue_stopped(net_queue) || + (!netif_carrier_ok(queue->vif->dev) && + test_bit(QUEUE_STATUS_RX_STALLED, &queue->status)))) + set_bit(QUEUE_STATUS_RX_PURGE_EVENT, &queue->status); xenvif_kick_thread(queue); return IRQ_HANDLED; @@ -125,16 +138,14 @@ void xenvif_wake_queue(struct xenvif_queue *queue) netif_tx_wake_queue(netdev_get_tx_queue(dev, id)); } -/* Callback to wake the queue and drain it on timeout */ -static void xenvif_wake_queue_callback(unsigned long data) +/* Callback to wake the queue's thread and turn the carrier off on timeout */ +static void xenvif_rx_stalled(unsigned long data) { struct xenvif_queue *queue = (struct xenvif_queue *)data; if (xenvif_queue_stopped(queue)) { - netdev_err(queue->vif->dev, "draining TX queue\n"); - queue->rx_queue_purge = true; + set_bit(QUEUE_STATUS_RX_PURGE_EVENT, &queue->status); xenvif_kick_thread(queue); - xenvif_wake_queue(queue); } } @@ -183,11 +194,11 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) * drain. */ if (!xenvif_rx_ring_slots_available(queue, min_slots_needed)) { - queue->wake_queue.function = xenvif_wake_queue_callback; - queue->wake_queue.data = (unsigned long)queue; + queue->rx_stalled.function = xenvif_rx_stalled; + queue->rx_stalled.data = (unsigned long)queue; xenvif_stop_queue(queue); - mod_timer(&queue->wake_queue, - jiffies + rx_drain_timeout_jiffies); + mod_timer(&queue->rx_stalled, + jiffies + rx_drain_timeout_jiffies); } skb_queue_tail(&queue->rx_queue, skb); @@ -515,7 +526,7 @@ int xenvif_init_queue(struct xenvif_queue *queue) queue->grant_tx_handle[i] = NETBACK_INVALID_HANDLE; } - init_timer(&queue->wake_queue); + init_timer(&queue->rx_stalled); netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll, XENVIF_NAPI_WEIGHT); @@ -666,7 +677,7 @@ void xenvif_disconnect(struct xenvif *vif) queue = &vif->queues[queue_index]; if (queue->task) { - del_timer_sync(&queue->wake_queue); + del_timer_sync(&queue->rx_stalled); kthread_stop(queue->task); queue->task = NULL; } @@ -708,16 +719,12 @@ void xenvif_free(struct xenvif *vif) /* Here we want to avoid timeout messages if an skb can be legitimately * stuck somewhere else. Realistically this could be an another vif's * internal or QDisc queue. That another vif also has this - * rx_drain_timeout_msecs timeout, but the timer only ditches the - * internal queue. After that, the QDisc queue can put in worst case - * XEN_NETIF_RX_RING_SIZE / MAX_SKB_FRAGS skbs into that another vif's - * internal queue, so we need several rounds of such timeouts until we - * can be sure that no another vif should have skb's from us. We are - * not sending more skb's, so newly stuck packets are not interesting - * for us here. + * rx_drain_timeout_msecs timeout, so give it time to drain out. + * Although if that other guest wakes up just before its timeout happens + * and takes only one skb from QDisc, it can hold onto other skbs for a + * longer period. */ - unsigned int worst_case_skb_lifetime = (rx_drain_timeout_msecs/1000) * - DIV_ROUND_UP(XENVIF_QUEUE_LENGTH, (XEN_NETIF_RX_RING_SIZE / MAX_SKB_FRAGS)); + unsigned int worst_case_skb_lifetime = (rx_drain_timeout_msecs/1000); unregister_netdev(vif->dev); diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 6c4cc0f44da5..aa2093325be1 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1869,8 +1869,7 @@ void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx) static inline int rx_work_todo(struct xenvif_queue *queue) { return (!skb_queue_empty(&queue->rx_queue) && - xenvif_rx_ring_slots_available(queue, queue->rx_last_skb_slots)) || - queue->rx_queue_purge; + xenvif_rx_ring_slots_available(queue, queue->rx_last_skb_slots)); } static inline int tx_work_todo(struct xenvif_queue *queue) @@ -1935,6 +1934,75 @@ static void xenvif_start_queue(struct xenvif_queue *queue) xenvif_wake_queue(queue); } +/* Only called from the queue's thread, it handles the situation when the guest + * doesn't post enough requests on the receiving ring. + * First xenvif_start_xmit disables QDisc and start a timer, and then either the + * timer fires, or the guest send an interrupt after posting new request. If it + * is the timer, the carrier is turned off here. + * */ +static void xenvif_rx_purge_event(struct xenvif_queue *queue) +{ + /* Either the last unsuccesful skb or at least 1 slot should fit */ + int needed = queue->rx_last_skb_slots ? + queue->rx_last_skb_slots : 1; + + /* It is assumed that if the guest post new slots after this, the RX + * interrupt will set the QUEUE_STATUS_RX_PURGE_EVENT bit and wake up + * the thread again + */ + set_bit(QUEUE_STATUS_RX_STALLED, &queue->status); + if (!xenvif_rx_ring_slots_available(queue, needed)) { + rtnl_lock(); + if (netif_carrier_ok(queue->vif->dev)) { + /* Timer fired and there are still no slots. Turn off + * everything except the interrupts + */ + netif_carrier_off(queue->vif->dev); + skb_queue_purge(&queue->rx_queue); + queue->rx_last_skb_slots = 0; + if (net_ratelimit()) + netdev_err(queue->vif->dev, "Carrier off due to lack of guest response on queue %d\n", queue->id); + } else { + /* Probably an another queue already turned the carrier + * off, make sure nothing is stucked in the internal + * queue of this queue + */ + skb_queue_purge(&queue->rx_queue); + queue->rx_last_skb_slots = 0; + } + rtnl_unlock(); + } else if (!netif_carrier_ok(queue->vif->dev)) { + unsigned int num_queues = queue->vif->num_queues; + unsigned int i; + /* The carrier was down, but an interrupt kicked + * the thread again after new requests were + * posted + */ + clear_bit(QUEUE_STATUS_RX_STALLED, + &queue->status); + rtnl_lock(); + netif_carrier_on(queue->vif->dev); + netif_tx_wake_all_queues(queue->vif->dev); + rtnl_unlock(); + + for (i = 0; i < num_queues; i++) { + struct xenvif_queue *temp = &queue->vif->queues[i]; + + xenvif_napi_schedule_or_enable_events(temp); + } + if (net_ratelimit()) + netdev_err(queue->vif->dev, "Carrier on again\n"); + } else { + /* Queuing were stopped, but the guest posted + * new requests and sent an interrupt + */ + clear_bit(QUEUE_STATUS_RX_STALLED, + &queue->status); + del_timer_sync(&queue->rx_stalled); + xenvif_start_queue(queue); + } +} + int xenvif_kthread_guest_rx(void *data) { struct xenvif_queue *queue = data; @@ -1944,8 +2012,12 @@ int xenvif_kthread_guest_rx(void *data) wait_event_interruptible(queue->wq, rx_work_todo(queue) || queue->vif->disabled || + test_bit(QUEUE_STATUS_RX_PURGE_EVENT, &queue->status) || kthread_should_stop()); + if (kthread_should_stop()) + break; + /* This frontend is found to be rogue, disable it in * kthread context. Currently this is only set when * netback finds out frontend sends malformed packet, @@ -1955,24 +2027,21 @@ int xenvif_kthread_guest_rx(void *data) */ if (unlikely(queue->vif->disabled && queue->id == 0)) xenvif_carrier_off(queue->vif); - - if (kthread_should_stop()) - break; - - if (queue->rx_queue_purge) { + else if (unlikely(test_and_clear_bit(QUEUE_STATUS_RX_PURGE_EVENT, + &queue->status))) { + xenvif_rx_purge_event(queue); + } else if (!netif_carrier_ok(queue->vif->dev)) { + /* Another queue stalled and turned the carrier off, so + * purge the internal queue of queues which were not + * blocked + */ skb_queue_purge(&queue->rx_queue); - queue->rx_queue_purge = false; + queue->rx_last_skb_slots = 0; } if (!skb_queue_empty(&queue->rx_queue)) xenvif_rx_action(queue); - if (skb_queue_empty(&queue->rx_queue) && - xenvif_queue_stopped(queue)) { - del_timer_sync(&queue->wake_queue); - xenvif_start_queue(queue); - } - cond_resched(); } |