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SubjectRe: Linux 2.6.21-rc5

* Ingo Molnar <mingo@elte.hu> wrote:

> my first quick guess was to extend np->priv locking to the whole of
> nv_start_xmit/nv_start_xmit_optimized - while that appeared to make
> the crash a bit less likely, it did not prevent it. So there must be
> some other, more fundamental problem be left as well. At first glance
> the SMP locking looks OK, so maybe the ring indices are messed up
> somehow and we got into a 'ring head bites the tail' scenario?

to be specific, the patch below is what i tried - but it didnt
completely fix the crash.

Ingo

---
drivers/net/forcedeth.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
Index: linux/drivers/net/forcedeth.c
===================================================================
--- linux.orig/drivers/net/forcedeth.c
+++ linux/drivers/net/forcedeth.c
@@ -1650,9 +1650,10 @@ static int nv_start_xmit(struct sk_buff
((skb_shinfo(skb)->frags[i].size & (NV_TX2_TSO_MAX_SIZE-1)) ? 1 : 0);
}

+ spin_lock_irq(&np->lock);
+
empty_slots = nv_get_empty_tx_slots(np);
if (unlikely(empty_slots <= entries)) {
- spin_lock_irq(&np->lock);
netif_stop_queue(dev);
np->tx_stop = 1;
spin_unlock_irq(&np->lock);
@@ -1718,8 +1719,6 @@ static int nv_start_xmit(struct sk_buff
tx_flags_extra = skb->ip_summed == CHECKSUM_PARTIAL ?
NV_TX2_CHECKSUM_L3 | NV_TX2_CHECKSUM_L4 : 0;

- spin_lock_irq(&np->lock);
-
/* set tx flags */
start_tx->flaglen |= cpu_to_le32(tx_flags | tx_flags_extra);
np->put_tx.orig = put_tx;
@@ -1766,9 +1765,10 @@ static int nv_start_xmit_optimized(struc
((skb_shinfo(skb)->frags[i].size & (NV_TX2_TSO_MAX_SIZE-1)) ? 1 : 0);
}

+ spin_lock_irq(&np->lock);
+
empty_slots = nv_get_empty_tx_slots(np);
if (unlikely(empty_slots <= entries)) {
- spin_lock_irq(&np->lock);
netif_stop_queue(dev);
np->tx_stop = 1;
spin_unlock_irq(&np->lock);
@@ -1846,8 +1846,6 @@ static int nv_start_xmit_optimized(struc
start_tx->txvlan = 0;
}

- spin_lock_irq(&np->lock);
-
/* set tx flags */
start_tx->flaglen |= cpu_to_le32(tx_flags | tx_flags_extra);
np->put_tx.ex = put_tx;
@@ -3484,6 +3482,7 @@ static void nv_do_nic_poll(unsigned long
struct net_device *dev = (struct net_device *) data;
struct fe_priv *np = netdev_priv(dev);
u8 __iomem *base = get_hwbase(dev);
+ unsigned long flags;
u32 mask = 0;

/*
@@ -3519,7 +3518,7 @@ static void nv_do_nic_poll(unsigned long
printk(KERN_INFO "forcedeth: MAC in recoverable error state\n");
if (netif_running(dev)) {
netif_tx_lock_bh(dev);
- spin_lock(&np->lock);
+ spin_lock_irqsave(&np->lock, flags);
/* stop engines */
nv_stop_rx(dev);
nv_stop_tx(dev);
@@ -3545,7 +3544,7 @@ static void nv_do_nic_poll(unsigned long
/* restart rx engine */
nv_start_rx(dev);
nv_start_tx(dev);
- spin_unlock(&np->lock);
+ spin_unlock_irqrestore(&np->lock, flags);
netif_tx_unlock_bh(dev);
}
}
-
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