From 1df726ef0a700587a712a3660b2caa8e533c7de9 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Mon, 5 Sep 2011 08:58:29 +0100
Subject: [PATCH] NET: am79c961: fix race in link status code
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>
---
drivers/net/arm/am79c961a.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/net/arm/am79c961a.c b/drivers/net/arm/am79c961a.c
index 52fe21e1e2cd..3b1416e3d217 100644
--- a/drivers/net/arm/am79c961a.c
+++ b/drivers/net/arm/am79c961a.c
@@ -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) {
--
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