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mv643xx_eth: Fix race condition in mv643xx_eth_free_tx_descs 

mv643xx_eth: Fix race condition in mv643xx_eth_free_tx_descs

This bug was found and isolated by Thibaut VARENE <T-Bone@parisc-linux.org>
and Jarek Poplawski <jarkao2@o2.pl>.  This patch is a modification of their
fixes.  We acquire and release the lock for each descriptor that is freed
to minimize the time the lock is held.

Signed-off-by: Jeff Garzik <jeff@garzik.org>
This commit is contained in:
Dale Farnsworth 2007-01-23 09:52:25 -07:00 committed by Jeff Garzik
parent 3196265e97
commit d344bff9c3
1 changed files with 9 additions and 2 deletions
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11
drivers/net/mv643xx_eth.c
View File

@ -314,6 +314,13 @@ int mv643xx_eth_free_tx_descs(struct net_device *dev, int force)
while (mp->tx_desc_count > 0) { while (mp->tx_desc_count > 0) {
spin_lock_irqsave(&mp->lock, flags); spin_lock_irqsave(&mp->lock, flags);
/* tx_desc_count might have changed before acquiring the lock */
if (mp->tx_desc_count <= 0) {
spin_unlock_irqrestore(&mp->lock, flags);
return released;
}
tx_index = mp->tx_used_desc_q; tx_index = mp->tx_used_desc_q;
desc = &mp->p_tx_desc_area[tx_index]; desc = &mp->p_tx_desc_area[tx_index];
cmd_sts = desc->cmd_sts; cmd_sts = desc->cmd_sts;
@ -332,13 +339,13 @@ int mv643xx_eth_free_tx_descs(struct net_device *dev, int force)
if (skb) if (skb)
mp->tx_skb[tx_index] = NULL; mp->tx_skb[tx_index] = NULL;
spin_unlock_irqrestore(&mp->lock, flags);
if (cmd_sts & ETH_ERROR_SUMMARY) { if (cmd_sts & ETH_ERROR_SUMMARY) {
printk("%s: Error in TX\n", dev->name); printk("%s: Error in TX\n", dev->name);
mp->stats.tx_errors++; mp->stats.tx_errors++;
} }
spin_unlock_irqrestore(&mp->lock, flags);
if (cmd_sts & ETH_TX_FIRST_DESC) if (cmd_sts & ETH_TX_FIRST_DESC)
dma_unmap_single(NULL, addr, count, DMA_TO_DEVICE); dma_unmap_single(NULL, addr, count, DMA_TO_DEVICE);
else else