linux-kernel - Re: [PATCH 4/12] drivers/gpio: Add missing unlock

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Message-ID: <Pine.LNX.4.64.1003291822470.21896@ask.diku.dk>
Date:	Mon, 29 Mar 2010 18:23:30 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 4/12] drivers/gpio: Add missing unlock

From: Julia Lawall <julia@...u.dk>

In an error handling case the lock is not unlocked.  The return is
converted to a goto, to share the unlock at the end of the function.

A simplified version of the semantic patch that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
expression E1;
identifier f;
@@

f (...) { <+...
* spin_lock_irqsave (E1,...);
... when != E1
* return ...;
...+> }
// </smpl>

Signed-off-by: Julia Lawall <julia@...u.dk>

---
Corrected patch.  Adjusted the return value.

 drivers/gpio/timbgpio.c             |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/timbgpio.c b/drivers/gpio/timbgpio.c
index d4295fa..871608b 100644
--- a/drivers/gpio/timbgpio.c
+++ b/drivers/gpio/timbgpio.c
@@ -130,6 +130,7 @@ static int timbgpio_irq_type(unsigned irq, unsigned trigger)
 	unsigned long flags;
 	u32 lvr, flr, bflr = 0;
 	u32 ver;
+	int ret = 0;
 
 	if (offset < 0 || offset > tgpio->gpio.ngpio)
 		return -EINVAL;
@@ -153,8 +154,10 @@ static int timbgpio_irq_type(unsigned irq, unsigned trigger)
 	}
 
 	if ((trigger & IRQ_TYPE_EDGE_BOTH) == IRQ_TYPE_EDGE_BOTH) {
-		if (ver < 3)
-			return -EINVAL;
+		if (ver < 3) {
+			ret = -EINVAL;
+			goto out;
+		}
 		else {
 			flr |= 1 << offset;
 			bflr |= 1 << offset;
@@ -174,9 +177,10 @@ static int timbgpio_irq_type(unsigned irq, unsigned trigger)
 		iowrite32(bflr, tgpio->membase + TGPIO_BFLR);
 
 	iowrite32(1 << offset, tgpio->membase + TGPIO_ICR);
-	spin_unlock_irqrestore(&tgpio->lock, flags);
 
-	return 0;
+out:
+	spin_unlock_irqrestore(&tgpio->lock, flags);
+	return ret;
 }
 
 static void timbgpio_irq(unsigned int irq, struct irq_desc *desc)
--
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