can: sja1000: fix {pre,post}_irq() handling and IRQ handler return value

commit 2fea6cd303c0d0cd9067da31d873b6a6d5bd75e7 upstream.

This patch fixes the issue that the sja1000_interrupt() function may have
returned IRQ_NONE without processing the optional pre_irq() and post_irq()
function before. Further the irq processing counter 'n' is moved to the end of
the while statement to return correct IRQ_[NONE|HANDLED] values at error
conditions.

Reported-by: Wolfgang Grandegger <wg@grandegger.com>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[bwh: Backported to 3.2: s/SJA1000_IER/REG_IER/; s/SJA1000_IR/REG_IR/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 6a1acfe..568b821 100644 (file)
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -488,19 +488,19 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
        uint8_t isrc, status;
        int n = 0;
 
-       /* Shared interrupts and IRQ off? */
-       if (priv->read_reg(priv, REG_IER) == IRQ_OFF)
-               return IRQ_NONE;
-
        if (priv->pre_irq)
                priv->pre_irq(priv);
 
+       /* Shared interrupts and IRQ off? */
+       if (priv->read_reg(priv, REG_IER) == IRQ_OFF)
+               goto out;
+
        while ((isrc = priv->read_reg(priv, REG_IR)) && (n < SJA1000_MAX_IRQ)) {
-               n++;
+
                status = priv->read_reg(priv, SJA1000_REG_SR);
                /* check for absent controller due to hw unplug */
                if (status == 0xFF && sja1000_is_absent(priv))
-                       return IRQ_NONE;
+                       goto out;
 
                if (isrc & IRQ_WUI)
                        dev_warn(dev->dev.parent, "wakeup interrupt\n");
@@ -519,7 +519,7 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
                                status = priv->read_reg(priv, SJA1000_REG_SR);
                                /* check for absent controller */
                                if (status == 0xFF && sja1000_is_absent(priv))
-                                       return IRQ_NONE;
+                                       goto out;
                        }
                }
                if (isrc & (IRQ_DOI | IRQ_EI | IRQ_BEI | IRQ_EPI | IRQ_ALI)) {
@@ -527,8 +527,9 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
                        if (sja1000_err(dev, isrc, status))
                                break;
                }
+               n++;
        }
-
+out:
        if (priv->post_irq)
                priv->post_irq(priv);