The data structure which contains the timer is about to be freed. Make
sure no callback is running.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Grant Likely <grant.likely@linaro.org>
---
 drivers/block/xsysace.c |    2 ++
 1 file changed, 2 insertions(+)

Index: tip/drivers/block/xsysace.c
===================================================================
--- tip.orig/drivers/block/xsysace.c
+++ tip/drivers/block/xsysace.c
@@ -1088,6 +1088,8 @@ static void ace_teardown(struct ace_devi
 	if (ace->irq)
 		free_irq(ace->irq, ace);
 
+	del_timer_sync(&ace->stall_timer);
+
 	iounmap(ace->baseaddr);
 }