From 2561cc15e3816e4323f9e79a6890bff94c0bbec2 Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Mon, 11 Aug 2014 13:01:44 +0100 Subject: xen-netback: Don't deschedule NAPI when carrier off In the patch called "xen-netback: Turn off the carrier if the guest is not able to receive" NAPI was descheduled when the carrier was set off. That's not what most of the drivers do, and we don't have any specific reason to do so as well, so revert that change. Signed-off-by: Zoltan Kiss Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xenproject.org Acked-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 48a55cda979b..bfd10cb9c8de 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -78,12 +78,8 @@ 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 || - !netif_carrier_ok(queue->vif->dev))) { + if (unlikely(queue->vif->disabled)) { napi_complete(napi); return 0; } -- cgit v1.2.3 From ea2c5e134237eadc9924ce821ded678750024549 Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Tue, 12 Aug 2014 11:48:06 +0100 Subject: xen-netback: move NAPI add/remove calls Originally netif_napi_add was in xenvif_init_queue and netif_napi_del was in xenvif_deinit_queue, while kthreads were handled in xenvif_connect and xenvif_disconnect. Move netif_napi_add and netif_napi_del to xenvif_connect and xenvif_disconnect so that they reside together with kthread operations. Signed-off-by: Wei Liu Cc: Ian Campbell Cc: Zoltan Kiss Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index bfd10cb9c8de..5f3d6c06fcf7 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -524,9 +524,6 @@ int xenvif_init_queue(struct xenvif_queue *queue) init_timer(&queue->rx_stalled); - netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll, - XENVIF_NAPI_WEIGHT); - return 0; } @@ -614,6 +611,9 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref, wake_up_process(queue->task); wake_up_process(queue->dealloc_task); + netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll, + XENVIF_NAPI_WEIGHT); + return 0; err_rx_unbind: @@ -672,6 +672,8 @@ void xenvif_disconnect(struct xenvif *vif) for (queue_index = 0; queue_index < num_queues; ++queue_index) { queue = &vif->queues[queue_index]; + netif_napi_del(&queue->napi); + if (queue->task) { del_timer_sync(&queue->rx_stalled); kthread_stop(queue->task); @@ -704,7 +706,6 @@ void xenvif_disconnect(struct xenvif *vif) void xenvif_deinit_queue(struct xenvif_queue *queue) { free_xenballooned_pages(MAX_PENDING_REQS, queue->mmap_pages); - netif_napi_del(&queue->napi); } void xenvif_free(struct xenvif *vif) -- cgit v1.2.3 From a64bd934528e26e8956112e43a279fba2ee0634e Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Tue, 12 Aug 2014 11:48:07 +0100 Subject: xen-netback: don't stop dealloc kthread too early Reference count the number of packets in host stack, so that we don't stop the deallocation thread too early. If not, we can end up with xenvif_free permanently waiting for deallocation thread to unmap grefs. Reported-by: Thomas Leonard Signed-off-by: Wei Liu Cc: Ian Campbell Cc: Zoltan Kiss Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 5f3d6c06fcf7..0aaca902699a 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -43,6 +43,23 @@ #define XENVIF_QUEUE_LENGTH 32 #define XENVIF_NAPI_WEIGHT 64 +/* This function is used to set SKBTX_DEV_ZEROCOPY as well as + * increasing the inflight counter. We need to increase the inflight + * counter because core driver calls into xenvif_zerocopy_callback + * which calls xenvif_skb_zerocopy_complete. + */ +void xenvif_skb_zerocopy_prepare(struct xenvif_queue *queue, + struct sk_buff *skb) +{ + skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; + atomic_inc(&queue->inflight_packets); +} + +void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue) +{ + atomic_dec(&queue->inflight_packets); +} + static inline void xenvif_stop_queue(struct xenvif_queue *queue) { struct net_device *dev = queue->vif->dev; @@ -557,6 +574,7 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref, init_waitqueue_head(&queue->wq); init_waitqueue_head(&queue->dealloc_wq); + atomic_set(&queue->inflight_packets, 0); if (tx_evtchn == rx_evtchn) { /* feature-split-event-channels == 0 */ -- cgit v1.2.3 From b1252858213f39700dac1bc3295b6e88f6cce24b Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Tue, 12 Aug 2014 11:48:08 +0100 Subject: xen-netback: remove loop waiting function The original implementation relies on a loop to check if all inflight packets are freed. Now we have proper reference counting, there's no need to use loop anymore. Signed-off-by: Wei Liu Cc: Ian Campbell Cc: Zoltan Kiss Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 29 ----------------------------- 1 file changed, 29 deletions(-) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 0aaca902699a..e29e15dca86e 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -660,25 +660,6 @@ void xenvif_carrier_off(struct xenvif *vif) rtnl_unlock(); } -static void xenvif_wait_unmap_timeout(struct xenvif_queue *queue, - unsigned int worst_case_skb_lifetime) -{ - int i, unmap_timeout = 0; - - for (i = 0; i < MAX_PENDING_REQS; ++i) { - if (queue->grant_tx_handle[i] != NETBACK_INVALID_HANDLE) { - unmap_timeout++; - schedule_timeout(msecs_to_jiffies(1000)); - if (unmap_timeout > worst_case_skb_lifetime && - net_ratelimit()) - netdev_err(queue->vif->dev, - "Page still granted! Index: %x\n", - i); - i = -1; - } - } -} - void xenvif_disconnect(struct xenvif *vif) { struct xenvif_queue *queue = NULL; @@ -731,21 +712,11 @@ void xenvif_free(struct xenvif *vif) struct xenvif_queue *queue = NULL; unsigned int num_queues = vif->num_queues; unsigned int queue_index; - /* 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, 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); unregister_netdev(vif->dev); for (queue_index = 0; queue_index < num_queues; ++queue_index) { queue = &vif->queues[queue_index]; - xenvif_wait_unmap_timeout(queue, worst_case_skb_lifetime); xenvif_deinit_queue(queue); } -- cgit v1.2.3 From e24f8191cc35ae3780b4656a6befae8b8657edc2 Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Mon, 25 Aug 2014 16:44:00 +0100 Subject: xen-netback: move netif_napi_add before binding interrupt Interrupt is enabled when bind_interdomain_evtchn_to_irqhandler returns. If there's interrupt pending interrupt handler is invoked. NAPI needs to be initialised before binding interrupt otherwise the interrupt handler will try to scheduling a NAPI instance that is not initialised yet, resulting in kernel OOPS. This fixes a regression introduced in ea2c5e13 ("xen-netback: move NAPI add/remove calls"). Ideally function calls to create kthreads should also be moved before binding but I intent to fix this regression with minimal changes and refactor the code with another patch. Reported-by: Thomas Leonard Signed-off-by: Wei Liu Cc: Ian Campbell Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index e29e15dca86e..f379689dde30 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -576,6 +576,9 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref, init_waitqueue_head(&queue->dealloc_wq); atomic_set(&queue->inflight_packets, 0); + netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll, + XENVIF_NAPI_WEIGHT); + if (tx_evtchn == rx_evtchn) { /* feature-split-event-channels == 0 */ err = bind_interdomain_evtchn_to_irqhandler( @@ -629,9 +632,6 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref, wake_up_process(queue->task); wake_up_process(queue->dealloc_task); - netif_napi_add(queue->vif->dev, &queue->napi, xenvif_poll, - XENVIF_NAPI_WEIGHT); - return 0; err_rx_unbind: -- cgit v1.2.3 From bc96f648df1bbc2729abbb84513cf4f64273a1f1 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 22 Oct 2014 14:08:53 +0100 Subject: xen-netback: make feature-rx-notify mandatory Frontends that do not provide feature-rx-notify may stall because netback depends on the notification from frontend to wake the guest Rx thread (even if can_queue is false). This could be fixed but feature-rx-notify was introduced in 2006 and I am not aware of any frontends that do not implement this. Signed-off-by: David Vrabel Acked-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index f379689dde30..c6759b1ec18d 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -60,16 +60,6 @@ void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue) atomic_dec(&queue->inflight_packets); } -static inline void xenvif_stop_queue(struct xenvif_queue *queue) -{ - struct net_device *dev = queue->vif->dev; - - if (!queue->vif->can_queue) - return; - - netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id)); -} - int xenvif_schedulable(struct xenvif *vif) { return netif_running(vif->dev) && @@ -209,7 +199,7 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) if (!xenvif_rx_ring_slots_available(queue, min_slots_needed)) { queue->rx_stalled.function = xenvif_rx_stalled; queue->rx_stalled.data = (unsigned long)queue; - xenvif_stop_queue(queue); + netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id)); mod_timer(&queue->rx_stalled, jiffies + rx_drain_timeout_jiffies); } -- cgit v1.2.3 From f48da8b14d04ca87ffcffe68829afd45f926ec6a Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 22 Oct 2014 14:08:54 +0100 Subject: xen-netback: fix unlimited guest Rx internal queue and carrier flapping Netback needs to discard old to-guest skb's (guest Rx queue drain) and it needs detect guest Rx stalls (to disable the carrier so packets are discarded earlier), but the current implementation is very broken. 1. The check in hard_start_xmit of the slot availability did not consider the number of packets that were already in the guest Rx queue. This could allow the queue to grow without bound. The guest stops consuming packets and the ring was allowed to fill leaving S slot free. Netback queues a packet requiring more than S slots (ensuring that the ring stays with S slots free). Netback queue indefinately packets provided that then require S or fewer slots. 2. The Rx stall detection is not triggered in this case since the (host) Tx queue is not stopped. 3. If the Tx queue is stopped and a guest Rx interrupt occurs, netback will consider this an Rx purge event which may result in it taking the carrier down unnecessarily. It also considers a queue with only 1 slot free as unstalled (even though the next packet might not fit in this). The internal guest Rx queue is limited by a byte length (to 512 Kib, enough for half the ring). The (host) Tx queue is stopped and started based on this limit. This sets an upper bound on the amount of memory used by packets on the internal queue. This allows the estimatation of the number of slots for an skb to be removed (it wasn't a very good estimate anyway). Instead, the guest Rx thread just waits for enough free slots for a maximum sized packet. skbs queued on the internal queue have an 'expires' time (set to the current time plus the drain timeout). The guest Rx thread will detect when the skb at the head of the queue has expired and discard expired skbs. This sets a clear upper bound on the length of time an skb can be queued for. For a guest being destroyed the maximum time needed to wait for all the packets it sent to be dropped is still the drain timeout (10 s) since it will not be sending new packets. Rx stall detection is reintroduced in a later commit. Signed-off-by: David Vrabel Reviewed-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 59 +++++++------------------------------ 1 file changed, 11 insertions(+), 48 deletions(-) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index c6759b1ec18d..a134d52f55b4 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -43,6 +43,9 @@ #define XENVIF_QUEUE_LENGTH 32 #define XENVIF_NAPI_WEIGHT 64 +/* Number of bytes allowed on the internal guest Rx queue. */ +#define XENVIF_RX_QUEUE_BYTES (XEN_NETIF_RX_RING_SIZE/2 * PAGE_SIZE) + /* This function is used to set SKBTX_DEV_ZEROCOPY as well as * increasing the inflight counter. We need to increase the inflight * counter because core driver calls into xenvif_zerocopy_callback @@ -63,7 +66,8 @@ void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue) int xenvif_schedulable(struct xenvif *vif) { return netif_running(vif->dev) && - test_bit(VIF_STATUS_CONNECTED, &vif->status); + test_bit(VIF_STATUS_CONNECTED, &vif->status) && + !vif->disabled; } static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id) @@ -104,16 +108,7 @@ 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; @@ -141,24 +136,13 @@ void xenvif_wake_queue(struct xenvif_queue *queue) netif_tx_wake_queue(netdev_get_tx_queue(dev, id)); } -/* 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)) { - set_bit(QUEUE_STATUS_RX_PURGE_EVENT, &queue->status); - xenvif_kick_thread(queue); - } -} - static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct xenvif *vif = netdev_priv(dev); struct xenvif_queue *queue = NULL; unsigned int num_queues = vif->num_queues; u16 index; - int min_slots_needed; + struct xenvif_rx_cb *cb; BUG_ON(skb->dev != dev); @@ -181,30 +165,10 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) !xenvif_schedulable(vif)) goto drop; - /* At best we'll need one slot for the header and one for each - * frag. - */ - min_slots_needed = 1 + skb_shinfo(skb)->nr_frags; + cb = XENVIF_RX_CB(skb); + cb->expires = jiffies + rx_drain_timeout_jiffies; - /* If the skb is GSO then we'll also need an extra slot for the - * metadata. - */ - if (skb_is_gso(skb)) - min_slots_needed++; - - /* If the skb can't possibly fit in the remaining slots - * then turn off the queue to give the ring a chance to - * drain. - */ - if (!xenvif_rx_ring_slots_available(queue, min_slots_needed)) { - queue->rx_stalled.function = xenvif_rx_stalled; - queue->rx_stalled.data = (unsigned long)queue; - netif_tx_stop_queue(netdev_get_tx_queue(dev, queue->id)); - mod_timer(&queue->rx_stalled, - jiffies + rx_drain_timeout_jiffies); - } - - skb_queue_tail(&queue->rx_queue, skb); + xenvif_rx_queue_tail(queue, skb); xenvif_kick_thread(queue); return NETDEV_TX_OK; @@ -498,6 +462,8 @@ int xenvif_init_queue(struct xenvif_queue *queue) init_timer(&queue->credit_timeout); queue->credit_window_start = get_jiffies_64(); + queue->rx_queue_max = XENVIF_RX_QUEUE_BYTES; + skb_queue_head_init(&queue->rx_queue); skb_queue_head_init(&queue->tx_queue); @@ -529,8 +495,6 @@ int xenvif_init_queue(struct xenvif_queue *queue) queue->grant_tx_handle[i] = NETBACK_INVALID_HANDLE; } - init_timer(&queue->rx_stalled); - return 0; } @@ -664,7 +628,6 @@ void xenvif_disconnect(struct xenvif *vif) netif_napi_del(&queue->napi); if (queue->task) { - del_timer_sync(&queue->rx_stalled); kthread_stop(queue->task); queue->task = NULL; } -- cgit v1.2.3 From ecf08d2dbb96d5a4b4bcc53a39e8d29cc8fef02e Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 22 Oct 2014 14:08:55 +0100 Subject: xen-netback: reintroduce guest Rx stall detection If a frontend not receiving packets it is useful to detect this and turn off the carrier so packets are dropped early instead of being queued and drained when they expire. A to-guest queue is stalled if it doesn't have enough free slots for a an extended period of time (default 60 s). If at least one queue is stalled, the carrier is turned off (in the expectation that the other queues will soon stall as well). The carrier is only turned on once all queues are ready. When the frontend connects, all the queues start in the stalled state and only become ready once the frontend queues enough Rx requests. Signed-off-by: David Vrabel Reviewed-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/net/xen-netback/interface.c') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index a134d52f55b4..895fe84011e7 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -419,6 +419,8 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, vif->queues = NULL; vif->num_queues = 0; + spin_lock_init(&vif->lock); + dev->netdev_ops = &xenvif_netdev_ops; dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM | @@ -505,7 +507,6 @@ void xenvif_carrier_on(struct xenvif *vif) dev_set_mtu(vif->dev, ETH_DATA_LEN); netdev_update_features(vif->dev); set_bit(VIF_STATUS_CONNECTED, &vif->status); - netif_carrier_on(vif->dev); if (netif_running(vif->dev)) xenvif_up(vif); rtnl_unlock(); @@ -565,6 +566,8 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref, disable_irq(queue->rx_irq); } + queue->stalled = true; + task = kthread_create(xenvif_kthread_guest_rx, (void *)queue, "%s-guest-rx", queue->name); if (IS_ERR(task)) { -- cgit v1.2.3