[12/22] Cyclades PC300 driver: locking improvements
From: Andrea Shepard <hidden>
Date: 2012-01-30 02:54:22
Also in:
lkml
Subsystem:
cyclades pc300 driver, networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Avoid redundant do/while in CPC_LOCK/CPC_UNLOCK macros; hold the lock during DMA buffer writes in cpc_queue_xmit() to avert a potential race condition. Signed-off-by: Andrea Shepard <redacted>
diff --git a/drivers/net/wan/pc300_drv.c b/drivers/net/wan/pc300_drv.c
index 36cf3b0..14500eb 100644
--- a/drivers/net/wan/pc300_drv.c
+++ b/drivers/net/wan/pc300_drv.c@@ -243,15 +243,15 @@ static char rcsid[] = #include "pc300.h" -#define CPC_LOCK(card,flags) \ - do { \ - spin_lock_irqsave(&card->card_lock, flags); \ - } while (0) +#define CPC_LOCK(card, flags) \ + { \ + spin_lock_irqsave(&((card)->card_lock), (flags)); \ + } -#define CPC_UNLOCK(card,flags) \ - do { \ - spin_unlock_irqrestore(&card->card_lock, flags); \ - } while (0) +#define CPC_UNLOCK(card, flags) \ + { \ + spin_unlock_irqrestore(&((card)->card_lock), (flags)); \ + } #undef PC300_DEBUG_PCI #undef PC300_DEBUG_INTR
@@ -1971,8 +1971,10 @@ static int cpc_queue_xmit(struct sk_buff *skb, struct net_device *dev) return 0; } + CPC_LOCK(card, flags); /* Write buffer to DMA buffers */ if (dma_buf_write(card, ch, (u8 *) skb->data, skb->len) != 0) { + CPC_UNLOCK(card, flags); printk(KERN_ERR "%s: write error. Dropping TX packet.\n", dev->name); #ifdef PC300_DEBUG_QUEUE
@@ -1985,7 +1987,8 @@ static int cpc_queue_xmit(struct sk_buff *skb, struct net_device *dev) stats->tx_errors++; stats->tx_dropped++; return 0; - } + } else + CPC_UNLOCK(card, flags); #ifdef PC300_DEBUG_TX printk("%s T:", dev->name); for (i = 0; i < skb->len; i++)