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From 12b438d3f818974bc5dc2813013a61b93077569e Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 17 Nov 2009 12:02:43 +0100
Subject: [PATCH 031/270] drivers: net: at91_ether: Make mdio protection -rt
safe
Neither the phy interrupt nor the timer callback which updates the
link status in absense of a phy interrupt are taking lp->lock which
serializes the MDIO access. This works on mainline as at91 is an UP
machine. On preempt-rt the timer callback can run even in the
spin_lock_irq(&lp->lock) protected code pathes because spin_lock_irq
is neither disabling interrupts nor disabling preemption.
Fix this by adding proper locking to at91ether_phy_interrupt() and
at91_check_ether() which serializes the access on -rt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/net/ethernet/cadence/at91_ether.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/ethernet/cadence/at91_ether.c b/drivers/net/ethernet/cadence/at91_ether.c
index 9061170..6b9e006 100644
--- a/drivers/net/ethernet/cadence/at91_ether.c
+++ b/drivers/net/ethernet/cadence/at91_ether.c
@@ -201,7 +201,9 @@ static irqreturn_t at91ether_phy_interrupt(int irq, void *dev_id)
struct net_device *dev = (struct net_device *) dev_id;
struct at91_private *lp = netdev_priv(dev);
unsigned int phy;
+ unsigned long flags;
+ spin_lock_irqsave(&lp->lock, flags);
/*
* This hander is triggered on both edges, but the PHY chips expect
* level-triggering. We therefore have to check if the PHY actually has
@@ -243,6 +245,7 @@ static irqreturn_t at91ether_phy_interrupt(int irq, void *dev_id)
done:
disable_mdi();
+ spin_unlock_irqrestore(&lp->lock, flags);
return IRQ_HANDLED;
}
@@ -399,9 +402,11 @@ static void at91ether_check_link(unsigned long dev_id)
struct net_device *dev = (struct net_device *) dev_id;
struct at91_private *lp = netdev_priv(dev);
+ spin_lock_irq(&lp->lock);
enable_mdi();
update_linkspeed(dev, 1);
disable_mdi();
+ spin_unlock_irq(&lp->lock);
mod_timer(&lp->check_timer, jiffies + LINK_POLL_INTERVAL);
}
--
1.7.10.4
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