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NET: am79c961: fix race in link status code

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The link status code operates from a timer, and writes the index
register without first taking a lock.  A well-placed interrupt
between writing the index register and reading the data register
could change the index register on us, which will return wrong data.
Add the necessary lock.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2011-09-05 08:58:29 +01:00
parent fb492c9160
commit 1df726ef0a
1 changed files with 3 additions and 0 deletions
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3
drivers/net/arm/am79c961a.c
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@ -308,8 +308,11 @@ static void am79c961_timer(unsigned long data)
struct net_device *dev = (struct net_device *)data;
struct dev_priv *priv = netdev_priv(dev);
unsigned int lnkstat, carrier;
unsigned long flags;
spin_lock_irqsave(&priv->chip_lock, flags);
lnkstat = read_ireg(dev->base_addr, ISALED0) & ISALED0_LNKST;
spin_unlock_irqrestore(&priv->chip_lock, flags);
carrier = netif_carrier_ok(dev);
if (lnkstat && !carrier) {