[patch 083/164] ARM: 6146/1: sa1111: Prevent deadlock in resume path

Greg KH
2010-07-01T22:06:15Z

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

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

From: =?UTF-8?q?Marek=20Va=C5=A1ut?= <marek.vasut@gmail.com>

commit 3defb2476166445982a90c12d33f8947e75476c4 upstream.

This patch reorganises the sa1111_resume() function in a manner the spinlock
happens after calling the sa1111_wake(). This fixes two bugs:

1) This function called sa1111_wake() which tried to claim the same spinlock
the sa1111_resume() already claimed. This would result in certain deadlock.

Original idea for this part: Russell King <rmk+kernel@arm.linux.org.uk>

2) The function didn't unlock the spinlock in case the chip didn't report
correct ID.

Original idea for this part: Julia Lawall <julia@diku.dk>

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/arm/common/sa1111.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/arch/arm/common/sa1111.c
+++ b/arch/arm/common/sa1111.c
@@ -887,8 +887,6 @@ static int sa1111_resume(struct platform
if (!save)
return 0;

- spin_lock_irqsave(&sachip->lock, flags);
-
/*
* Ensure that the SA1111 is still here.
* FIXME: shouldn't do this here.
@@ -905,6 +903,13 @@ static int sa1111_resume(struct platform
* First of all, wake up the chip.
*/
sa1111_wake(sachip);
+
+ /*
+ * Only lock for write ops. Also, sa1111_wake must be called with
+ * released spinlock!
+ */
+ spin_lock_irqsave(&sachip->lock, flags);
+
sa1111_writel(0, sachip->base + SA1111_INTC + SA1111_INTEN0);
sa1111_writel(0, sachip->base + SA1111_INTC + SA1111_INTEN1);