[PATCH] mfd: mc13xxx-core: Initialize the lock prior to using it

[PATCH] mfd: mc13xxx-core: Initialize the lock prior to using it

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam@freescale.com>

After request_threaded_irq() is called there is a chance that an interrupt
may occur before the 'mc13xxx->lock' is initialized, which will trigger a kernel
warning.

In order to prevent that, move the initialization of 'mc13xxx->lock' prior to
requesting the interrupts.

Suggested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
 drivers/mfd/mc13xxx-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/mc13xxx-core.c b/drivers/mfd/mc13xxx-core.c
index 06e64b6..9e296c4 100644
--- a/drivers/mfd/mc13xxx-core.c
+++ b/drivers/mfd/mc13xxx-core.c
@@ -660,13 +660,13 @@ int mc13xxx_common_init(struct device *dev)
 	if (ret)
 		return ret;
 
+	mutex_init(&mc13xxx->lock);
+
 	ret = request_threaded_irq(mc13xxx->irq, NULL, mc13xxx_irq_thread,
 			IRQF_ONESHOT | IRQF_TRIGGER_HIGH, "mc13xxx", mc13xxx);
 	if (ret)
 		return ret;
 
-	mutex_init(&mc13xxx->lock);
-
 	if (mc13xxx_probe_flags_dt(mc13xxx) < 0 && pdata)
 		mc13xxx->flags = pdata->flags;
 
-- 
1.8.3.2

Re: [PATCH] mfd: mc13xxx-core: Initialize the lock prior to using it

[Russell King - ARM Linux]

On Tue, Apr 15, 2014 at 07:43:10PM -0300, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@freescale.com>
> 
> After request_threaded_irq() is called there is a chance that an interrupt
> may occur before the 'mc13xxx->lock' is initialized, which will trigger a kernel
> warning.

I'd suggest... "which will trigger a kernel oops" because that's what
you got - it killed the IRQ thread, which then caused a few other
problems along the way.

> In order to prevent that, move the initialization of 'mc13xxx->lock' prior to
> requesting the interrupts.
> 
> Suggested-by: Russell King <rmk+kernel@arm.linux.org.uk>
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

Patch looks good, and should fix the reported issue... so with the above
description fixed,

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

Thanks.

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