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

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.

Cc: stable@kernel.org [3.2+]
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 04a3f1b756a8..192b0d118df4 100644
--- 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)) {