netfront contains two locking problems found by lockdep:
1. rx_lock is a normal spinlock, and tx_lock is an irq spinlock. This
means that in normal use, tx_lock may be taken by an interrupt routine
while rx_lock is held. However, netif_disconnect_backend takes them
in the order tx_lock->rx_lock, which could lead to a deadlock. Reverse
them.
2. rx_lock can also be used in softirq context, so it should be taken/released
with spin_(un)lock_bh.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxxxx>
Cc: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>
diff -r a69029562c74 linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c Thu Apr 12
14:13:33 2007 -0700
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c Thu Apr 12
14:19:42 2007 -0700
@@ -622,14 +622,14 @@ static int network_open(struct net_devic
memset(&np->stats, 0, sizeof(np->stats));
- spin_lock(&np->rx_lock);
+ spin_lock_bh(&np->rx_lock);
if (netfront_carrier_ok(np)) {
network_alloc_rx_buffers(dev);
np->rx.sring->rsp_event = np->rx.rsp_cons + 1;
if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
netif_rx_schedule(dev);
}
- spin_unlock(&np->rx_lock);
+ spin_unlock_bh(&np->rx_lock);
network_maybe_wake_tx(dev);
@@ -1307,10 +1307,10 @@ static int netif_poll(struct net_device
int pages_flipped = 0;
int err;
- spin_lock(&np->rx_lock);
+ spin_lock_bh(&np->rx_lock);
if (unlikely(!netfront_carrier_ok(np))) {
- spin_unlock(&np->rx_lock);
+ spin_unlock_bh(&np->rx_lock);
return 0;
}
@@ -1478,7 +1478,7 @@ err:
local_irq_restore(flags);
}
- spin_unlock(&np->rx_lock);
+ spin_unlock_bh(&np->rx_lock);
return more_to_do;
}
@@ -1520,7 +1520,7 @@ static void netif_release_rx_bufs(struct
skb_queue_head_init(&free_list);
- spin_lock(&np->rx_lock);
+ spin_lock_bh(&np->rx_lock);
for (id = 0; id < NET_RX_RING_SIZE; id++) {
if ((ref = np->grant_rx_ref[id]) == GRANT_INVALID_REF) {
@@ -1588,7 +1588,7 @@ static void netif_release_rx_bufs(struct
while ((skb = __skb_dequeue(&free_list)) != NULL)
dev_kfree_skb(skb);
- spin_unlock(&np->rx_lock);
+ spin_unlock_bh(&np->rx_lock);
}
static int network_close(struct net_device *dev)
@@ -1708,8 +1708,8 @@ static int network_connect(struct net_de
IPRINTK("device %s has %sing receive path.\n",
dev->name, np->copying_receiver ? "copy" : "flipp");
+ spin_lock_bh(&np->rx_lock);
spin_lock_irq(&np->tx_lock);
- spin_lock(&np->rx_lock);
/*
* Recovery procedure:
@@ -1761,7 +1761,7 @@ static int network_connect(struct net_de
network_tx_buf_gc(dev);
network_alloc_rx_buffers(dev);
- spin_unlock(&np->rx_lock);
+ spin_unlock_bh(&np->rx_lock);
spin_unlock_irq(&np->tx_lock);
return 0;
@@ -1818,7 +1818,7 @@ static ssize_t store_rxbuf_min(struct cl
if (target > RX_MAX_TARGET)
target = RX_MAX_TARGET;
- spin_lock(&np->rx_lock);
+ spin_lock_bh(&np->rx_lock);
if (target > np->rx_max_target)
np->rx_max_target = target;
np->rx_min_target = target;
@@ -1827,7 +1827,7 @@ static ssize_t store_rxbuf_min(struct cl
network_alloc_rx_buffers(netdev);
- spin_unlock(&np->rx_lock);
+ spin_unlock_bh(&np->rx_lock);
return len;
}
@@ -1861,7 +1861,7 @@ static ssize_t store_rxbuf_max(struct cl
if (target > RX_MAX_TARGET)
target = RX_MAX_TARGET;
- spin_lock(&np->rx_lock);
+ spin_lock_bh(&np->rx_lock);
if (target < np->rx_min_target)
np->rx_min_target = target;
np->rx_max_target = target;
@@ -1870,7 +1870,7 @@ static ssize_t store_rxbuf_max(struct cl
network_alloc_rx_buffers(netdev);
- spin_unlock(&np->rx_lock);
+ spin_unlock_bh(&np->rx_lock);
return len;
}
@@ -2033,10 +2033,10 @@ static void netif_disconnect_backend(str
static void netif_disconnect_backend(struct netfront_info *info)
{
/* Stop old i/f to prevent errors whilst we rebuild the state. */
+ spin_lock_bh(&info->rx_lock);
spin_lock_irq(&info->tx_lock);
- spin_lock(&info->rx_lock);
netfront_carrier_off(info);
- spin_unlock(&info->rx_lock);
+ spin_unlock_bh(&info->rx_lock);
spin_unlock_irq(&info->tx_lock);
if (info->irq)
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