[015/102] rtc: handle errors correctly in rtc_irq_set_state()

[Greg KH]

3.0-stable review patch.  If anyone has any objections, please let us know.

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

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

commit 2c4f57d12df7696d65b0247bfd57fd082a7719e6 upstream.

The code checks the correctness of the parameters, but unconditionally
arms/disarms the hrtimer.

The result is that a random task might arm/disarm rtc timer and surprise
the real owner by either generating events or by stopping them.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/rtc/interface.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -656,6 +656,8 @@ int rtc_irq_set_state(struct rtc_device
 		err = -EBUSY;
 	if (rtc->irq_task != task)
 		err = -EACCES;
+	if (err)
+		goto out;
 
 	if (enabled) {
 		ktime_t period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
@@ -664,6 +666,7 @@ int rtc_irq_set_state(struct rtc_device
 		hrtimer_cancel(&rtc->pie_timer);
 	}
 	rtc->pie_enabled = enabled;
+out:
 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 
 	return err;


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