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Date: Tue, 12 Aug 2014 10:35:31 -0400
From: Sowmini Varadhan <sowmini.varadhan@...cle.com>
To: sowmini.varadhan@...cle.com, davem@...emloft.net,
raghuram.kothakota@...cle.com
Cc: netdev@...r.kernel.org
Subject: [PATCH net-next 3/3] sunvnet: Schedule maybe_tx_wakeup as a tasklet
from ldc_rx path
This patch must be applied after
"[PATCH net-next 2/3] sunvnet: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN"
At the tail of vnet_event(), if we hit the maybe_tx_wakeup()
condition, we try to take the netif_tx_lock() in the
recv-interrupt-context and can deadlock with dev_watchdog().
Two changes to fix this:
- The contents of maybe_tx_wakeup() should be moved into
vnet_tx_timeout
- vnet_event() should kick off a tasklet that triggers
netif_wake_queue()
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
Acked-by: Raghuram Kothakota <raghuram.kothakota@...cle.com>
---
drivers/net/ethernet/sun/sunvnet.c | 52 +++++++++++++++++++++++---------------
drivers/net/ethernet/sun/sunvnet.h | 4 +++
2 files changed, 36 insertions(+), 20 deletions(-)
diff --git a/drivers/net/ethernet/sun/sunvnet.c b/drivers/net/ethernet/sun/sunvnet.c
index 39c39bf..c75a638 100644
--- a/drivers/net/ethernet/sun/sunvnet.c
+++ b/drivers/net/ethernet/sun/sunvnet.c
@@ -32,6 +32,8 @@ MODULE_DESCRIPTION("Sun LDOM virtual network driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_MODULE_VERSION);
+static void vnet_tx_timeout(struct net_device *dev);
+
/* Heuristic for the number of times to exponentially backoff and
* retry sending an LDC trigger when EAGAIN is encountered
*/
@@ -489,28 +491,13 @@ static int handle_mcast(struct vnet_port *port, void *msgbuf)
return 0;
}
-static void maybe_tx_wakeup(struct vnet *vp)
+static void maybe_tx_wakeup(unsigned long param)
{
+ struct vnet *vp = (struct vnet *)param;
struct net_device *dev = vp->dev;
netif_tx_lock(dev);
- if (likely(netif_queue_stopped(dev))) {
- struct vnet_port *port;
- int wake = 1;
-
- list_for_each_entry(port, &vp->port_list, list) {
- struct vio_dring_state *dr;
-
- dr = &port->vio.drings[VIO_DRIVER_TX_RING];
- if (vnet_tx_dring_avail(dr) <
- VNET_TX_WAKEUP_THRESH(dr)) {
- wake = 0;
- break;
- }
- }
- if (wake)
- netif_wake_queue(dev);
- }
+ vnet_tx_timeout(dev);
netif_tx_unlock(dev);
}
@@ -587,8 +574,13 @@ static void vnet_event(void *arg, int event)
break;
}
spin_unlock(&vio->lock);
+ /* Kick off a tasklet to wake the queue. We cannot call
+ * maybe_tx_wakeup directly here because we could deadlock on
+ * netif_tx_lock() with dev_watchdog()
+ */
if (unlikely(tx_wakeup && err != -ECONNRESET))
- maybe_tx_wakeup(port->vp);
+ tasklet_schedule(&port->vp->vnet_tx_wakeup);
+
local_irq_restore(flags);
}
@@ -764,7 +756,25 @@ out_dropped:
static void vnet_tx_timeout(struct net_device *dev)
{
- /* XXX Implement me XXX */
+ struct vnet *vp = netdev_priv(dev);
+
+ if (likely(netif_queue_stopped(dev))) {
+ struct vnet_port *port;
+ int wake = 1;
+
+ list_for_each_entry(port, &vp->port_list, list) {
+ struct vio_dring_state *dr;
+
+ dr = &port->vio.drings[VIO_DRIVER_TX_RING];
+ if (vnet_tx_dring_avail(dr) <
+ VNET_TX_WAKEUP_THRESH(dr)) {
+ wake = 0;
+ break;
+ }
+ }
+ if (wake)
+ netif_wake_queue(dev);
+ }
}
static int vnet_open(struct net_device *dev)
@@ -1071,6 +1081,7 @@ static struct vnet *vnet_new(const u64 *local_mac)
vp = netdev_priv(dev);
spin_lock_init(&vp->lock);
+ tasklet_init(&vp->vnet_tx_wakeup, maybe_tx_wakeup, (unsigned long)vp);
vp->dev = dev;
INIT_LIST_HEAD(&vp->port_list);
@@ -1130,6 +1141,7 @@ static void vnet_cleanup(void)
vp = list_first_entry(&vnet_list, struct vnet, list);
list_del(&vp->list);
dev = vp->dev;
+ tasklet_kill(&vp->vnet_tx_wakeup);
/* vio_unregister_driver() should have cleaned up port_list */
BUG_ON(!list_empty(&vp->port_list));
unregister_netdev(dev);
diff --git a/drivers/net/ethernet/sun/sunvnet.h b/drivers/net/ethernet/sun/sunvnet.h
index d347a5b..0e872aa 100644
--- a/drivers/net/ethernet/sun/sunvnet.h
+++ b/drivers/net/ethernet/sun/sunvnet.h
@@ -1,6 +1,8 @@
#ifndef _SUNVNET_H
#define _SUNVNET_H
+#include <linux/interrupt.h>
+
#define DESC_NCOOKIES(entry_size) \
((entry_size) - sizeof(struct vio_net_desc))
@@ -78,6 +80,8 @@ struct vnet {
struct list_head list;
u64 local_mac;
+
+ struct tasklet_struct vnet_tx_wakeup;
};
#endif /* _SUNVNET_H */
--
1.8.4.2
--
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