>From Dale Farnsworth <[EMAIL PROTECTED]>
mv643xx_eth: Fix race condition in mv643xx_eth_free_tx_descs
This bug was found and isolated by Thibaut VARENE <[EMAIL PROTECTED]>
and Jarek Poplawski <[EMAIL PROTECTED]>. 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.
---
drivers/net/mv643xx_eth.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index c41ae42..b3bf864 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -314,6 +314,13 @@ int mv643xx_eth_free_tx_descs(struct net
while (mp->tx_desc_count > 0) {
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;
desc = &mp->p_tx_desc_area[tx_index];
cmd_sts = desc->cmd_sts;
@@ -332,13 +339,13 @@ int mv643xx_eth_free_tx_descs(struct net
if (skb)
mp->tx_skb[tx_index] = NULL;
- spin_unlock_irqrestore(&mp->lock, flags);
-
if (cmd_sts & ETH_ERROR_SUMMARY) {
printk("%s: Error in TX\n", dev->name);
mp->stats.tx_errors++;
}
+ spin_unlock_irqrestore(&mp->lock, flags);
+
if (cmd_sts & ETH_TX_FIRST_DESC)
dma_unmap_single(NULL, addr, count, DMA_TO_DEVICE);
else
-
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