Merge branch 'xen-netback'

David Vrabel says:

====================
xen-netback: guest Rx queue drain and stall fixes

This series fixes two critical xen-netback bugs.

1. Netback may consume all of host memory by queuing an unlimited
   number of skb on the internal guest Rx queue.  This behaviour is
   guest triggerable.

2. Carrier flapping under high traffic rates which reduces
   performance.

The first patch is a prerequite.  Removing support for frontends with
feature-rx-notify makes it easier to reason about the correctness of
netback since it no longer has to support this outdated and broken
mode.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 17 deletions

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index d4eb8d2e9cb7..083ecc93fe5e 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -176,10 +176,11 @@ struct xenvif_queue { /* Per-queue data for xenvif */
 	char rx_irq_name[IRQ_NAME_SIZE]; /* DEVNAME-qN-rx */
 	struct xen_netif_rx_back_ring rx;
 	struct sk_buff_head rx_queue;
-	RING_IDX rx_last_skb_slots;
-	unsigned long status;
 
-	struct timer_list rx_stalled;
+	unsigned int rx_queue_max;
+	unsigned int rx_queue_len;
+	unsigned long last_rx_time;
+	bool stalled;
 
 	struct gnttab_copy grant_copy_op[MAX_GRANT_COPY_OPS];
 
@@ -199,18 +200,14 @@ struct xenvif_queue { /* Per-queue data for xenvif */
 	struct xenvif_stats stats;
 };
 
+/* Maximum number of Rx slots a to-guest packet may use, including the
+ * slot needed for GSO meta-data.
+ */
+#define XEN_NETBK_RX_SLOTS_MAX (MAX_SKB_FRAGS + 1)
+
 enum state_bit_shift {
 	/* This bit marks that the vif is 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 {
@@ -228,9 +225,6 @@ struct xenvif {
 	u8 ip_csum:1;
 	u8 ipv6_csum:1;
 
-	/* Internal feature information. */
-	u8 can_queue:1;	    /* can queue packets for receiver? */
-
 	/* Is this interface disabled? True when backend discovers
 	 * frontend is rogue.
 	 */
@@ -240,6 +234,9 @@ struct xenvif {
 	/* Queues */
 	struct xenvif_queue *queues;
 	unsigned int num_queues; /* active queues, resource allocated */
+	unsigned int stalled_queues;
+
+	spinlock_t lock;
 
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *xenvif_dbg_root;
@@ -249,6 +246,14 @@ struct xenvif {
 	struct net_device *dev;
 };
 
+struct xenvif_rx_cb {
+	unsigned long expires;
+	int meta_slots_used;
+	bool full_coalesce;
+};
+
+#define XENVIF_RX_CB(skb) ((struct xenvif_rx_cb *)(skb)->cb)
+
 static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif *vif)
 {
 	return to_xenbus_device(vif->dev->dev.parent);
@@ -272,8 +277,6 @@ void xenvif_xenbus_fini(void);
 
 int xenvif_schedulable(struct xenvif *vif);
 
-int xenvif_must_stop_queue(struct xenvif_queue *queue);
-
 int xenvif_queue_stopped(struct xenvif_queue *queue);
 void xenvif_wake_queue(struct xenvif_queue *queue);
 
@@ -296,6 +299,8 @@ void xenvif_kick_thread(struct xenvif_queue *queue);
 
 int xenvif_dealloc_kthread(void *data);
 
+void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb);
+
 /* Determine whether the needed number of slots (req) are available,
  * and set req_event if not.
  */