diff options
| author | Arjan van de Ven <arjan@infradead.org> | 2006-07-05 15:00:40 +0200 |
|---|---|---|
| committer | Jeff Garzik <jeff@garzik.org> | 2006-07-05 14:29:26 -0400 |
| commit | bce305f4fe779f29d99d414685243f5da0803254 (patch) | |
| tree | 67072c37319f3c6b091dec8094d342118fe3fd62 /drivers/net/8139too.c | |
| parent | 20ed7c094dfe33b0e15e8c60f60012b9278631d3 (diff) | |
| download | lwn-bce305f4fe779f29d99d414685243f5da0803254.tar.gz lwn-bce305f4fe779f29d99d414685243f5da0803254.zip | |
[PATCH] 8139too deadlock fix
> stack backtrace:
> [<f9099d31>] rtl8139_start_xmit+0xd9/0xff [8139too]
> [<c11ad5ea>] netpoll_send_skb+0x98/0xea
This seems to be a real deadlock...
So netpoll_send_skb takes the _xmit_lock, which is all nitty gritty
but then rtl8139_start_xmit comes around while that lock is taken, and
does
spin_unlock_irq(&tp->lock);
which.. enables interrupts and softirqs; this is quite bad because the
xmit lock is taken in softirq context for the watchdog like this:
[<c1200376>] _spin_lock+0x23/0x32
[<c11af282>] dev_watchdog+0x14/0xb1
[<c101dab2>] run_timer_softirq+0xf2/0x14a
[<c101a691>] __do_softirq+0x55/0xb0
[<c1004a8d>] do_softirq+0x58/0xbd
Which would deadlock now that the spin_unlock_irq() has enabled
irqs/softirqs while the _xmit_lock is still held.
The patch below turns this into a irqsave/irqrestore pair so that
interrupts don't get enabled unconditionally.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'drivers/net/8139too.c')
| -rw-r--r-- | drivers/net/8139too.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/net/8139too.c b/drivers/net/8139too.c index cd9718512d1c..e4f4eaff7679 100644 --- a/drivers/net/8139too.c +++ b/drivers/net/8139too.c @@ -1709,6 +1709,7 @@ static int rtl8139_start_xmit (struct sk_buff *skb, struct net_device *dev) void __iomem *ioaddr = tp->mmio_addr; unsigned int entry; unsigned int len = skb->len; + unsigned long flags; /* Calculate the next Tx descriptor entry. */ entry = tp->cur_tx % NUM_TX_DESC; @@ -1725,7 +1726,7 @@ static int rtl8139_start_xmit (struct sk_buff *skb, struct net_device *dev) return 0; } - spin_lock_irq(&tp->lock); + spin_lock_irqsave(&tp->lock, flags); RTL_W32_F (TxStatus0 + (entry * sizeof (u32)), tp->tx_flag | max(len, (unsigned int)ETH_ZLEN)); @@ -1736,7 +1737,7 @@ static int rtl8139_start_xmit (struct sk_buff *skb, struct net_device *dev) if ((tp->cur_tx - NUM_TX_DESC) == tp->dirty_tx) netif_stop_queue (dev); - spin_unlock_irq(&tp->lock); + spin_unlock_irqrestore(&tp->lock, flags); if (netif_msg_tx_queued(tp)) printk (KERN_DEBUG "%s: Queued Tx packet size %u to slot %d.\n", |