linux-kernel - [PATCH 3.2 096/185] can: sja1000: fix {pre,post}_irq() handling and IRQ handler return value

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Date:	Sun, 29 Dec 2013 03:08:44 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Oliver Hartkopp" <socketcan@...tkopp.net>,
	"Marc Kleine-Budde" <mkl@...gutronix.de>,
	"Wolfgang Grandegger" <wg@...ndegger.com>
Subject: [PATCH 3.2 096/185] can: sja1000: fix {pre,post}_irq() handling
 and IRQ handler return value

3.2.54-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Oliver Hartkopp <socketcan@...tkopp.net>

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@...ndegger.com>
Acked-by: Wolfgang Grandegger <wg@...ndegger.com>
Signed-off-by: Oliver Hartkopp <socketcan@...tkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
[bwh: Backported to 3.2: s/SJA1000_IER/REG_IER/; s/SJA1000_IR/REG_IR/]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -488,19 +488,19 @@ 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)
 			dev_warn(dev->dev.parent, "wakeup interrupt\n");
@@ -519,7 +519,7 @@ 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)) {
@@ -527,8 +527,9 @@ 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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