1 files changed, 201 insertions, 118 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 08f65996534c..6563f0713fc0 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -55,13 +55,20 @@
 bool separate_tx_rx_irq = 1;
 module_param(separate_tx_rx_irq, bool, 0644);
 
-/* When guest ring is filled up, qdisc queues the packets for us, but we have
- * to timeout them, otherwise other guests' packets can get stuck there
+/* The time that packets can stay on the guest Rx internal queue
+ * before they are dropped.
  */
 unsigned int rx_drain_timeout_msecs = 10000;
 module_param(rx_drain_timeout_msecs, uint, 0444);
 unsigned int rx_drain_timeout_jiffies;
 
+/* The length of time before the frontend is considered unresponsive
+ * because it isn't providing Rx slots.
+ */
+static unsigned int rx_stall_timeout_msecs = 60000;
+module_param(rx_stall_timeout_msecs, uint, 0444);
+static unsigned int rx_stall_timeout_jiffies;
+
 unsigned int xenvif_max_queues;
 module_param_named(max_queues, xenvif_max_queues, uint, 0644);
 MODULE_PARM_DESC(max_queues,
@@ -83,7 +90,6 @@ static void make_tx_response(struct xenvif_queue *queue,
                              s8       st);
 
 static inline int tx_work_todo(struct xenvif_queue *queue);
-static inline int rx_work_todo(struct xenvif_queue *queue);
 
 static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
                                              u16      id,
@@ -163,6 +169,69 @@ bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue, int needed)
         return false;
 }
 
+void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&queue->rx_queue.lock, flags);
+
+        __skb_queue_tail(&queue->rx_queue, skb);
+
+        queue->rx_queue_len += skb->len;
+        if (queue->rx_queue_len > queue->rx_queue_max)
+                netif_tx_stop_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
+
+        spin_unlock_irqrestore(&queue->rx_queue.lock, flags);
+}
+
+static struct sk_buff *xenvif_rx_dequeue(struct xenvif_queue *queue)
+{
+        struct sk_buff *skb;
+
+        spin_lock_irq(&queue->rx_queue.lock);
+
+        skb = __skb_dequeue(&queue->rx_queue);
+        if (skb)
+                queue->rx_queue_len -= skb->len;
+
+        spin_unlock_irq(&queue->rx_queue.lock);
+
+        return skb;
+}
+
+static void xenvif_rx_queue_maybe_wake(struct xenvif_queue *queue)
+{
+        spin_lock_irq(&queue->rx_queue.lock);
+
+        if (queue->rx_queue_len < queue->rx_queue_max)
+                netif_tx_wake_queue(netdev_get_tx_queue(queue->vif->dev, queue->id));
+
+        spin_unlock_irq(&queue->rx_queue.lock);
+}
+
+
+static void xenvif_rx_queue_purge(struct xenvif_queue *queue)
+{
+        struct sk_buff *skb;
+        while ((skb = xenvif_rx_dequeue(queue)) != NULL)
+                kfree_skb(skb);
+}
+
+static void xenvif_rx_queue_drop_expired(struct xenvif_queue *queue)
+{
+        struct sk_buff *skb;
+
+        for(;;) {
+                skb = skb_peek(&queue->rx_queue);
+                if (!skb)
+                        break;
+                if (time_before(jiffies, XENVIF_RX_CB(skb)->expires))
+                        break;
+                xenvif_rx_dequeue(queue);
+                kfree_skb(skb);
+        }
+}
+
 /*
  * Returns true if we should start a new receive buffer instead of
  * adding 'size' bytes to a buffer which currently contains 'offset'
@@ -237,13 +306,6 @@ static struct xenvif_rx_meta *get_next_rx_buffer(struct xenvif_queue *queue,
         return meta;
 }
 
-struct xenvif_rx_cb {
-        int meta_slots_used;
-        bool full_coalesce;
-};
-
-#define XENVIF_RX_CB(skb) ((struct xenvif_rx_cb *)(skb)->cb)
-
 /*
  * Set up the grant operations for this fragment. If it's a flipping
  * interface, we also set up the unmap request from here.
@@ -587,12 +649,15 @@ static void xenvif_rx_action(struct xenvif_queue *queue)
 
         skb_queue_head_init(&rxq);
 
-        while ((skb = skb_dequeue(&queue->rx_queue)) != NULL) {
+        while (xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX)
+               && (skb = xenvif_rx_dequeue(queue)) != NULL) {
                 RING_IDX max_slots_needed;
                 RING_IDX old_req_cons;
                 RING_IDX ring_slots_used;
                 int i;
 
+                queue->last_rx_time = jiffies;
+
                 /* We need a cheap worse case estimate for the number of
                  * slots we'll use.
                  */
@@ -634,15 +699,6 @@ static void xenvif_rx_action(struct xenvif_queue *queue)
                     skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6))
                         max_slots_needed++;
 
-                /* If the skb may not fit then bail out now */
-                if (!xenvif_rx_ring_slots_available(queue, max_slots_needed)) {
-                        skb_queue_head(&queue->rx_queue, skb);
-                        need_to_notify = true;
-                        queue->rx_last_skb_slots = max_slots_needed;
-                        break;
-                } else
-                        queue->rx_last_skb_slots = 0;
-
                 old_req_cons = queue->rx.req_cons;
                 XENVIF_RX_CB(skb)->meta_slots_used = xenvif_gop_skb(skb, &npo, queue);
                 ring_slots_used = queue->rx.req_cons - old_req_cons;
@@ -1869,12 +1925,6 @@ 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));
-}
-
 static inline int tx_work_todo(struct xenvif_queue *queue)
 {
         if (likely(RING_HAS_UNCONSUMED_REQUESTS(&queue->tx)))
@@ -1931,92 +1981,121 @@ err:
         return err;
 }
 
-static void xenvif_start_queue(struct xenvif_queue *queue)
+static void xenvif_queue_carrier_off(struct xenvif_queue *queue)
 {
-        if (xenvif_schedulable(queue->vif))
-                xenvif_wake_queue(queue);
+        struct xenvif *vif = queue->vif;
+
+        queue->stalled = true;
+
+        /* At least one queue has stalled? Disable the carrier. */
+        spin_lock(&vif->lock);
+        if (vif->stalled_queues++ == 0) {
+                netdev_info(vif->dev, "Guest Rx stalled");
+                netif_carrier_off(vif->dev);
+        }
+        spin_unlock(&vif->lock);
 }
 
-/* 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)
+static void xenvif_queue_carrier_on(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;
+        struct xenvif *vif = queue->vif;
 
-        /* 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();
+        queue->last_rx_time = jiffies; /* Reset Rx stall detection. */
+        queue->stalled = false;
 
-                for (i = 0; i < num_queues; i++) {
-                        struct xenvif_queue *temp = &queue->vif->queues[i];
+        /* All queues are ready? Enable the carrier. */
+        spin_lock(&vif->lock);
+        if (--vif->stalled_queues == 0) {
+                netdev_info(vif->dev, "Guest Rx ready");
+                netif_carrier_on(vif->dev);
+        }
+        spin_unlock(&vif->lock);
+}
 
-                        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);
+static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue)
+{
+        RING_IDX prod, cons;
+
+        prod = queue->rx.sring->req_prod;
+        cons = queue->rx.req_cons;
+
+        return !queue->stalled
+                && prod - cons < XEN_NETBK_RX_SLOTS_MAX
+                && time_after(jiffies,
+                              queue->last_rx_time + rx_stall_timeout_jiffies);
+}
+
+static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
+{
+        RING_IDX prod, cons;
+
+        prod = queue->rx.sring->req_prod;
+        cons = queue->rx.req_cons;
+
+        return queue->stalled
+                && prod - cons >= XEN_NETBK_RX_SLOTS_MAX;
+}
+
+static bool xenvif_have_rx_work(struct xenvif_queue *queue)
+{
+        return (!skb_queue_empty(&queue->rx_queue)
+                && xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX))
+                || xenvif_rx_queue_stalled(queue)
+                || xenvif_rx_queue_ready(queue)
+                || kthread_should_stop()
+                || queue->vif->disabled;
+}
+
+static long xenvif_rx_queue_timeout(struct xenvif_queue *queue)
+{
+        struct sk_buff *skb;
+        long timeout;
+
+        skb = skb_peek(&queue->rx_queue);
+        if (!skb)
+                return MAX_SCHEDULE_TIMEOUT;
+
+        timeout = XENVIF_RX_CB(skb)->expires - jiffies;
+        return timeout < 0 ? 0 : timeout;
+}
+
+/* Wait until the guest Rx thread has work.
+ *
+ * The timeout needs to be adjusted based on the current head of the
+ * queue (and not just the head at the beginning).  In particular, if
+ * the queue is initially empty an infinite timeout is used and this
+ * needs to be reduced when a skb is queued.
+ *
+ * This cannot be done with wait_event_timeout() because it only
+ * calculates the timeout once.
+ */
+static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
+{
+        DEFINE_WAIT(wait);
+
+        if (xenvif_have_rx_work(queue))
+                return;
+
+        for (;;) {
+                long ret;
+
+                prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
+                if (xenvif_have_rx_work(queue))
+                        break;
+                ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
+                if (!ret)
+                        break;
         }
+        finish_wait(&queue->wq, &wait);
 }
 
 int xenvif_kthread_guest_rx(void *data)
 {
         struct xenvif_queue *queue = data;
-        struct sk_buff *skb;
+        struct xenvif *vif = queue->vif;
 
-        while (!kthread_should_stop()) {
-                wait_event_interruptible(queue->wq,
-                                         rx_work_todo(queue) ||
-                                         queue->vif->disabled ||
-                                         test_bit(QUEUE_STATUS_RX_PURGE_EVENT, &queue->status) ||
-                                         kthread_should_stop());
+        for (;;) {
+                xenvif_wait_for_rx_work(queue);
 
                 if (kthread_should_stop())
                         break;
@@ -2028,35 +2107,38 @@ int xenvif_kthread_guest_rx(void *data)
                  * context so we defer it here, if this thread is
                  * associated with queue 0.
                  */
-                if (unlikely(queue->vif->disabled && queue->id == 0)) {
-                        xenvif_carrier_off(queue->vif);
-                } else if (unlikely(queue->vif->disabled)) {
-                        /* kthread_stop() would be called upon this thread soon,
-                         * be a bit proactive
-                         */
-                        skb_queue_purge(&queue->rx_queue);
-                        queue->rx_last_skb_slots = 0;
-                } 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_last_skb_slots = 0;
+                if (unlikely(vif->disabled && queue->id == 0)) {
+                        xenvif_carrier_off(vif);
+                        xenvif_rx_queue_purge(queue);
+                        continue;
                 }
 
                 if (!skb_queue_empty(&queue->rx_queue))
                         xenvif_rx_action(queue);
 
+                /* If the guest hasn't provided any Rx slots for a
+                 * while it's probably not responsive, drop the
+                 * carrier so packets are dropped earlier.
+                 */
+                if (xenvif_rx_queue_stalled(queue))
+                        xenvif_queue_carrier_off(queue);
+                else if (xenvif_rx_queue_ready(queue))
+                        xenvif_queue_carrier_on(queue);
+
+                /* Queued packets may have foreign pages from other
+                 * domains.  These cannot be queued indefinitely as
+                 * this would starve guests of grant refs and transmit
+                 * slots.
+                 */
+                xenvif_rx_queue_drop_expired(queue);
+
+                xenvif_rx_queue_maybe_wake(queue);
+
                 cond_resched();
         }
 
         /* Bin any remaining skbs */
-        while ((skb = skb_dequeue(&queue->rx_queue)) != NULL)
-                dev_kfree_skb(skb);
+        xenvif_rx_queue_purge(queue);
 
         return 0;
 }
@@ -2113,6 +2195,7 @@ static int __init netback_init(void)
                 goto failed_init;
 
         rx_drain_timeout_jiffies = msecs_to_jiffies(rx_drain_timeout_msecs);
+        rx_stall_timeout_jiffies = msecs_to_jiffies(rx_stall_timeout_msecs);
 
 #ifdef CONFIG_DEBUG_FS
         xen_netback_dbg_root = debugfs_create_dir("xen-netback", NULL);