From: Dale Farnsworth Date: Tue, 23 Jan 2007 16:52:25 +0000 (-0700) Subject: mv643xx_eth: Fix race condition in mv643xx_eth_free_tx_descs X-Git-Tag: v2.6.20-rc6~6^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d344bff9c36db17dc4765215495aaa7212c1eb6c;p=linux-2.6 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 and Jarek Poplawski . 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 --- diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c index c41ae4286e..b3bf864227 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_device *dev, int force) 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_device *dev, int force) 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