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Subject[ 65/72] can: sja1000: fix isr hang when hw is unplugged under load
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oliver Hartkopp <socketcan@hartkopp.net>

commit a7762b10c12a70c5dbf2253142764b728ac88c3a upstream.

In the case of hotplug enabled devices (PCMCIA/PCIeC) the removal of the
hardware can cause an infinite loop in the common sja1000 isr.

Use the already retrieved status register to indicate a possible hardware
removal and double check by reading the mode register in sja1000_is_absent.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/can/sja1000/sja1000.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -95,11 +95,16 @@ static void sja1000_write_cmdreg(struct
spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
}

+static int sja1000_is_absent(struct sja1000_priv *priv)
+{
+ return (priv->read_reg(priv, REG_MOD) == 0xFF);
+}
+
static int sja1000_probe_chip(struct net_device *dev)
{
struct sja1000_priv *priv = netdev_priv(dev);

- if (priv->reg_base && (priv->read_reg(priv, 0) == 0xFF)) {
+ if (priv->reg_base && sja1000_is_absent(priv)) {
printk(KERN_INFO "%s: probing @0x%lX failed\n",
DRV_NAME, dev->base_addr);
return 0;
@@ -493,6 +498,9 @@ irqreturn_t sja1000_interrupt(int irq, v
while ((isrc = priv->read_reg(priv, REG_IR)) && (n < SJA1000_MAX_IRQ)) {
n++;
status = priv->read_reg(priv, REG_SR);
+ /* check for absent controller due to hw unplug */
+ if (status == 0xFF && sja1000_is_absent(priv))
+ return IRQ_NONE;

if (isrc & IRQ_WUI)
dev_warn(dev->dev.parent, "wakeup interrupt\n");
@@ -509,6 +517,9 @@ irqreturn_t sja1000_interrupt(int irq, v
while (status & SR_RBS) {
sja1000_rx(dev);
status = priv->read_reg(priv, REG_SR);
+ /* check for absent controller */
+ if (status == 0xFF && sja1000_is_absent(priv))
+ return IRQ_NONE;
}
}
if (isrc & (IRQ_DOI | IRQ_EI | IRQ_BEI | IRQ_EPI | IRQ_ALI)) {



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