[PATCH 3.4 209/214] can: sja1000: fix {pre,post}_irq() handling and IRQ handler return value

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Acked-by: Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
[bwh: Backported to 3.2: s/SJA1000_IER/REG_IER/; s/SJA1000_IR/REG_IR/]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Qiang Huang <h.huangqiang@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/can/sja1000/sja1000.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -487,19 +487,19 @@ irqreturn_t sja1000_interrupt(int irq, v
 	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)
 			netdev_warn(dev, "wakeup interrupt\n");
@@ -518,7 +518,7 @@ irqreturn_t sja1000_interrupt(int irq, v
 				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)) {
@@ -526,8 +526,9 @@ irqreturn_t sja1000_interrupt(int irq, v
 			if (sja1000_err(dev, isrc, status))
 				break;
 		}
+		n++;
 	}
-
+out:
 	if (priv->post_irq)
 		priv->post_irq(priv);
 


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