1 files changed, 138 insertions, 33 deletions

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 301cc037fda8..20e9defa1060 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -38,6 +38,7 @@
 
 #include <xen/events.h>
 #include <asm/xen/hypercall.h>
+#include <xen/balloon.h>
 
 #define XENVIF_QUEUE_LENGTH 32
 #define XENVIF_NAPI_WEIGHT  64
@@ -62,35 +63,20 @@ static int xenvif_poll(struct napi_struct *napi, int budget)
         struct xenvif *vif = container_of(napi, struct xenvif, napi);
         int work_done;
 
+        /* 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.
+         */
+        if (unlikely(vif->disabled)) {
+                napi_complete(napi);
+                return 0;
+        }
+
         work_done = xenvif_tx_action(vif, budget);
 
         if (work_done < budget) {
-                int more_to_do = 0;
-                unsigned long flags;
-
-                /* It is necessary to disable IRQ before calling
-                 * RING_HAS_UNCONSUMED_REQUESTS. Otherwise we might
-                 * lose event from the frontend.
-                 *
-                 * Consider:
-                 *   RING_HAS_UNCONSUMED_REQUESTS
-                 *   <frontend generates event to trigger napi_schedule>
-                 *   __napi_complete
-                 *
-                 * This handler is still in scheduled state so the
-                 * event has no effect at all. After __napi_complete
-                 * this handler is descheduled and cannot get
-                 * scheduled again. We lose event in this case and the ring
-                 * will be completely stalled.
-                 */
-
-                local_irq_save(flags);
-
-                RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
-                if (!more_to_do)
-                        __napi_complete(napi);
-
-                local_irq_restore(flags);
+                napi_complete(napi);
+                xenvif_napi_schedule_or_enable_events(vif);
         }
 
         return work_done;
@@ -113,6 +99,18 @@ static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
         return IRQ_HANDLED;
 }
 
+static void xenvif_wake_queue(unsigned long data)
+{
+        struct xenvif *vif = (struct xenvif *)data;
+
+        if (netif_queue_stopped(vif->dev)) {
+                netdev_err(vif->dev, "draining TX queue\n");
+                vif->rx_queue_purge = true;
+                xenvif_kick_thread(vif);
+                netif_wake_queue(vif->dev);
+        }
+}
+
 static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         struct xenvif *vif = netdev_priv(dev);
@@ -121,7 +119,9 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
         BUG_ON(skb->dev != dev);
 
         /* Drop the packet if vif is not ready */
-        if (vif->task == NULL || !xenvif_schedulable(vif))
+        if (vif->task == NULL ||
+            vif->dealloc_task == NULL ||
+            !xenvif_schedulable(vif))
                 goto drop;
 
         /* At best we'll need one slot for the header and one for each
@@ -139,8 +139,13 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
          * then turn off the queue to give the ring a chance to
          * drain.
          */
-        if (!xenvif_rx_ring_slots_available(vif, min_slots_needed))
+        if (!xenvif_rx_ring_slots_available(vif, min_slots_needed)) {
+                vif->wake_queue.function = xenvif_wake_queue;
+                vif->wake_queue.data = (unsigned long)vif;
                 xenvif_stop_queue(vif);
+                mod_timer(&vif->wake_queue,
+                        jiffies + rx_drain_timeout_jiffies);
+        }
 
         skb_queue_tail(&vif->rx_queue, skb);
         xenvif_kick_thread(vif);
@@ -165,7 +170,7 @@ static void xenvif_up(struct xenvif *vif)
         enable_irq(vif->tx_irq);
         if (vif->tx_irq != vif->rx_irq)
                 enable_irq(vif->rx_irq);
-        xenvif_check_rx_xenvif(vif);
+        xenvif_napi_schedule_or_enable_events(vif);
 }
 
 static void xenvif_down(struct xenvif *vif)
@@ -233,6 +238,28 @@ static const struct xenvif_stat {
                 "rx_gso_checksum_fixup",
                 offsetof(struct xenvif, rx_gso_checksum_fixup)
         },
+        /* If (sent != success + fail), there are probably packets never
+         * freed up properly!
+         */
+        {
+                "tx_zerocopy_sent",
+                offsetof(struct xenvif, tx_zerocopy_sent),
+        },
+        {
+                "tx_zerocopy_success",
+                offsetof(struct xenvif, tx_zerocopy_success),
+        },
+        {
+                "tx_zerocopy_fail",
+                offsetof(struct xenvif, tx_zerocopy_fail)
+        },
+        /* Number of packets exceeding MAX_SKB_FRAG slots. You should use
+         * a guest with the same MAX_SKB_FRAG
+         */
+        {
+                "tx_frag_overflow",
+                offsetof(struct xenvif, tx_frag_overflow)
+        },
 };
 
 static int xenvif_get_sset_count(struct net_device *dev, int string_set)
@@ -321,11 +348,15 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
         vif->ip_csum = 1;
         vif->dev = dev;
 
+        vif->disabled = false;
+
         vif->credit_bytes = vif->remaining_credit = ~0UL;
         vif->credit_usec  = 0UL;
         init_timer(&vif->credit_timeout);
         vif->credit_window_start = get_jiffies_64();
 
+        init_timer(&vif->wake_queue);
+
         dev->netdev_ops = &xenvif_netdev_ops;
         dev->hw_features = NETIF_F_SG |
                 NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
@@ -342,8 +373,26 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
         vif->pending_prod = MAX_PENDING_REQS;
         for (i = 0; i < MAX_PENDING_REQS; i++)
                 vif->pending_ring[i] = i;
-        for (i = 0; i < MAX_PENDING_REQS; i++)
-                vif->mmap_pages[i] = NULL;
+        spin_lock_init(&vif->callback_lock);
+        spin_lock_init(&vif->response_lock);
+        /* If ballooning is disabled, this will consume real memory, so you
+         * better enable it. The long term solution would be to use just a
+         * bunch of valid page descriptors, without dependency on ballooning
+         */
+        err = alloc_xenballooned_pages(MAX_PENDING_REQS,
+                                       vif->mmap_pages,
+                                       false);
+        if (err) {
+                netdev_err(dev, "Could not reserve mmap_pages\n");
+                return ERR_PTR(-ENOMEM);
+        }
+        for (i = 0; i < MAX_PENDING_REQS; i++) {
+                vif->pending_tx_info[i].callback_struct = (struct ubuf_info)
+                        { .callback = xenvif_zerocopy_callback,
+                          .ctx = NULL,
+                          .desc = i };
+                vif->grant_tx_handle[i] = NETBACK_INVALID_HANDLE;
+        }
 
         /*
          * Initialise a dummy MAC address. We choose the numerically
@@ -381,12 +430,14 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
 
         BUG_ON(vif->tx_irq);
         BUG_ON(vif->task);
+        BUG_ON(vif->dealloc_task);
 
         err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
         if (err < 0)
                 goto err;
 
         init_waitqueue_head(&vif->wq);
+        init_waitqueue_head(&vif->dealloc_wq);
 
         if (tx_evtchn == rx_evtchn) {
                 /* feature-split-event-channels == 0 */
@@ -420,8 +471,8 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
                 disable_irq(vif->rx_irq);
         }
 
-        task = kthread_create(xenvif_kthread,
-                              (void *)vif, "%s", vif->dev->name);
+        task = kthread_create(xenvif_kthread_guest_rx,
+                              (void *)vif, "%s-guest-rx", vif->dev->name);
         if (IS_ERR(task)) {
                 pr_warn("Could not allocate kthread for %s\n", vif->dev->name);
                 err = PTR_ERR(task);
@@ -430,6 +481,16 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
 
         vif->task = task;
 
+        task = kthread_create(xenvif_dealloc_kthread,
+                              (void *)vif, "%s-dealloc", vif->dev->name);
+        if (IS_ERR(task)) {
+                pr_warn("Could not allocate kthread for %s\n", vif->dev->name);
+                err = PTR_ERR(task);
+                goto err_rx_unbind;
+        }
+
+        vif->dealloc_task = task;
+
         rtnl_lock();
         if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
                 dev_set_mtu(vif->dev, ETH_DATA_LEN);
@@ -440,6 +501,7 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
         rtnl_unlock();
 
         wake_up_process(vif->task);
+        wake_up_process(vif->dealloc_task);
 
         return 0;
 
@@ -473,10 +535,16 @@ void xenvif_disconnect(struct xenvif *vif)
                 xenvif_carrier_off(vif);
 
         if (vif->task) {
+                del_timer_sync(&vif->wake_queue);
                 kthread_stop(vif->task);
                 vif->task = NULL;
         }
 
+        if (vif->dealloc_task) {
+                kthread_stop(vif->dealloc_task);
+                vif->dealloc_task = NULL;
+        }
+
         if (vif->tx_irq) {
                 if (vif->tx_irq == vif->rx_irq)
                         unbind_from_irqhandler(vif->tx_irq, vif);
@@ -492,6 +560,43 @@ void xenvif_disconnect(struct xenvif *vif)
 
 void xenvif_free(struct xenvif *vif)
 {
+        int i, unmap_timeout = 0;
+        /* 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.
+         */
+        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));
+
+        for (i = 0; i < MAX_PENDING_REQS; ++i) {
+                if (vif->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(vif->dev,
+                                           "Page still granted! Index: %x\n",
+                                           i);
+                        /* If there are still unmapped pages, reset the loop to
+                         * start checking again. We shouldn't exit here until
+                         * dealloc thread and NAPI instance release all the
+                         * pages. If a kernel bug causes the skbs to stall
+                         * somewhere, the interface cannot be brought down
+                         * properly.
+                         */
+                        i = -1;
+                }
+        }
+
+        free_xenballooned_pages(MAX_PENDING_REQS, vif->mmap_pages);
+
         netif_napi_del(&vif->napi);
 
         unregister_netdev(vif->dev);