can: sja1000: fix isr hang when hw is unplugged under load

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>

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 04a3f1b..192b0d1 100644 (file)
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -95,11 +95,16 @@ static void sja1000_write_cmdreg(struct sja1000_priv *priv, u8 val)
        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, void *dev_id)
        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, void *dev_id)
                        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)) {