From 26c0e102585d5a4d311f5d6eb7f524d288e7f6b7 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Thu, 18 Dec 2014 11:13:06 +0000 Subject: xen-netback: support frontends without feature-rx-notify again Commit bc96f648df1bbc2729abbb84513cf4f64273a1f1 (xen-netback: make feature-rx-notify mandatory) incorrectly assumed that there were no frontends in use that did not support this feature. But the frontend driver in MiniOS does not and since this is used by (qemu) stubdoms, these stopped working. Netback sort of works as-is in this mode except: - If there are no Rx requests and the internal Rx queue fills, only the drain timeout will wake the thread. The default drain timeout of 10 s would give unacceptable pauses. - If an Rx stall was detected and the internal Rx queue is drained, then the Rx thread would never wake. Handle these two cases (when feature-rx-notify is disabled) by: - Reducing the drain timeout to 30 ms. - Disabling Rx stall detection. Reported-by: John Tested-by: John Signed-off-by: David Vrabel Reviewed-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/common.h | 4 +++- drivers/net/xen-netback/interface.c | 4 +++- drivers/net/xen-netback/netback.c | 27 ++++++++++++++------------- drivers/net/xen-netback/xenbus.c | 12 +++++++++--- 4 files changed, 29 insertions(+), 18 deletions(-) (limited to 'drivers/net/xen-netback') diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h index 083ecc9..5f1fda4 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -230,6 +230,8 @@ struct xenvif { */ bool disabled; unsigned long status; + unsigned long drain_timeout; + unsigned long stall_timeout; /* Queues */ struct xenvif_queue *queues; @@ -328,7 +330,7 @@ irqreturn_t xenvif_interrupt(int irq, void *dev_id); extern bool separate_tx_rx_irq; extern unsigned int rx_drain_timeout_msecs; -extern unsigned int rx_drain_timeout_jiffies; +extern unsigned int rx_stall_timeout_msecs; extern unsigned int xenvif_max_queues; #ifdef CONFIG_DEBUG_FS diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index a6a32d3..9259a73 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -166,7 +166,7 @@ static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev) goto drop; cb = XENVIF_RX_CB(skb); - cb->expires = jiffies + rx_drain_timeout_jiffies; + cb->expires = jiffies + vif->drain_timeout; xenvif_rx_queue_tail(queue, skb); xenvif_kick_thread(queue); @@ -414,6 +414,8 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, vif->ip_csum = 1; vif->dev = dev; vif->disabled = false; + vif->drain_timeout = msecs_to_jiffies(rx_drain_timeout_msecs); + vif->stall_timeout = msecs_to_jiffies(rx_stall_timeout_msecs); /* Start out with no queues. */ vif->queues = NULL; diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 4a509f7..908e65e 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -60,14 +60,12 @@ module_param(separate_tx_rx_irq, bool, 0644); */ 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; +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); @@ -2020,7 +2018,7 @@ static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue) return !queue->stalled && prod - cons < XEN_NETBK_RX_SLOTS_MAX && time_after(jiffies, - queue->last_rx_time + rx_stall_timeout_jiffies); + queue->last_rx_time + queue->vif->stall_timeout); } static bool xenvif_rx_queue_ready(struct xenvif_queue *queue) @@ -2038,8 +2036,9 @@ 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) + || (queue->vif->stall_timeout && + (xenvif_rx_queue_stalled(queue) + || xenvif_rx_queue_ready(queue))) || kthread_should_stop() || queue->vif->disabled; } @@ -2092,6 +2091,9 @@ int xenvif_kthread_guest_rx(void *data) struct xenvif_queue *queue = data; struct xenvif *vif = queue->vif; + if (!vif->stall_timeout) + xenvif_queue_carrier_on(queue); + for (;;) { xenvif_wait_for_rx_work(queue); @@ -2118,10 +2120,12 @@ int xenvif_kthread_guest_rx(void *data) * 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); + if (vif->stall_timeout) { + 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 @@ -2192,9 +2196,6 @@ static int __init netback_init(void) if (rc) 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); if (IS_ERR_OR_NULL(xen_netback_dbg_root)) diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c index d44cd19..efbaf2a 100644 --- a/drivers/net/xen-netback/xenbus.c +++ b/drivers/net/xen-netback/xenbus.c @@ -887,9 +887,15 @@ static int read_xenbus_vif_flags(struct backend_info *be) return -EOPNOTSUPP; if (xenbus_scanf(XBT_NIL, dev->otherend, - "feature-rx-notify", "%d", &val) < 0 || val == 0) { - xenbus_dev_fatal(dev, -EINVAL, "feature-rx-notify is mandatory"); - return -EINVAL; + "feature-rx-notify", "%d", &val) < 0) + val = 0; + if (!val) { + /* - Reduce drain timeout to poll more frequently for + * Rx requests. + * - Disable Rx stall detection. + */ + be->vif->drain_timeout = msecs_to_jiffies(30); + be->vif->stall_timeout = 0; } if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg", -- cgit v1.1