[PATCH -next] hrtimer: Fix hang seen if tick_init_highres() failed

2015-08-22 Thread Guenter Roeck 
Commit 75e3b37d0598 ("hrtimer: Drop return code of hrtimer_switch_to_hres()")
drops the return code of hrtimer_switch_to_hres(). While doing so, it also
drops the return statement itself on failure. This may cause a system hang.
Seen when running arm:multi_v7_defconfig in qemu with devicetree file
vexpress-v2p-ca9.

Fixes: 75e3b37d0598 ("hrtimer: Drop return code of hrtimer_switch_to_hres()")
Cc: Luiz Capitulino 
Signed-off-by: Guenter Roeck 
---
 kernel/time/hrtimer.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 5c4fe50e47d3..457a373e2181 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -695,6 +695,7 @@ static void hrtimer_switch_to_hres(void)
if (tick_init_highres()) {
printk(KERN_WARNING "Could not switch to high resolution "
"mode on CPU %d\n", base->cpu);
+   return;
}
base->hres_active = 1;
hrtimer_resolution = HIGH_RES_NSEC;
-- 
2.1.4

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Re: [PATCH -next] hrtimer: Fix hang seen if tick_init_highres() failed

2015-08-22 Thread Luiz Capitulino 
On Sat, 22 Aug 2015 01:10:47 -0700
Guenter Roeck  wrote:

> Commit 75e3b37d0598 ("hrtimer: Drop return code of hrtimer_switch_to_hres()")
> drops the return code of hrtimer_switch_to_hres(). While doing so, it also
> drops the return statement itself on failure. This may cause a system hang.
> Seen when running arm:multi_v7_defconfig in qemu with devicetree file
> vexpress-v2p-ca9.
> 
> Fixes: 75e3b37d0598 ("hrtimer: Drop return code of hrtimer_switch_to_hres()")
> Cc: Luiz Capitulino 
> Signed-off-by: Guenter Roeck 

Thanks for catching it Guenter!

Reviewed-by: Luiz Capitulino 

> ---
>  kernel/time/hrtimer.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
> index 5c4fe50e47d3..457a373e2181 100644
> --- a/kernel/time/hrtimer.c
> +++ b/kernel/time/hrtimer.c
> @@ -695,6 +695,7 @@ static void hrtimer_switch_to_hres(void)
>   if (tick_init_highres()) {
>   printk(KERN_WARNING "Could not switch to high resolution "
>   "mode on CPU %d\n", base->cpu);
> + return;
>   }
>   base->hres_active = 1;
>   hrtimer_resolution = HIGH_RES_NSEC;

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