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-rw-r--r--drivers/net/xen-netback/common.h15
-rw-r--r--drivers/net/xen-netback/interface.c49
-rw-r--r--drivers/net/xen-netback/netback.c97
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();
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-20 09:04:25 +0000