2012-11-21 01:54:11

by Liu, Chuansheng

Subject: [PATCH] watchdog: using u64 in get_sample_period()

In get_sample_period(), unsigned long is not enough:
watchdog_thresh * 2 * (NSEC_PER_SEC / 5)

case1: watchdog_thresh is 10 by default,
the sample value will be: 0xEE6B 2800

case2: set watchdog_thresh is 20,
the sample value will be: 0x1 DCD6 5000

>From case2, we need use u64 to express the sample period.
Otherwise, Changing the threshold thru proc often can
not be successful.

Signed-off-by: liu chuansheng <[email protected]>
---
kernel/watchdog.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9d4c8d5..dd4b80a 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -116,7 +116,7 @@ static unsigned long get_timestamp(int this_cpu)
return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
}

-static unsigned long get_sample_period(void)
+static u64 get_sample_period(void)
{
/*
* convert watchdog_thresh from seconds to ns
@@ -125,7 +125,7 @@ static unsigned long get_sample_period(void)
* and hard thresholds) to increment before the
* hardlockup detector generates a warning
*/
- return get_softlockup_thresh() * (NSEC_PER_SEC / 5);
+ return get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
}

/* Commands for resetting the watchdog */
--
1.7.0.4

2012-11-21 13:57:55

by Don Zickus

Subject: Re: [PATCH] watchdog: using u64 in get_sample_period()

On Wed, Nov 21, 2012 at 06:56:07PM +0800, Chuansheng Liu wrote:
>
> In get_sample_period(), unsigned long is not enough:
> watchdog_thresh * 2 * (NSEC_PER_SEC / 5)
>
> case1: watchdog_thresh is 10 by default,
> the sample value will be: 0xEE6B 2800
>
> case2: set watchdog_thresh is 20,
> the sample value will be: 0x1 DCD6 5000
>
> >From case2, we need use u64 to express the sample period.
> Otherwise, Changing the threshold thru proc often can
> not be successful.

I guess I should have tested 32-bit more. :-) Good catch.

Acked-by: Don Zickus <[email protected]>

>
> Signed-off-by: liu chuansheng <[email protected]>
> ---
> kernel/watchdog.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 9d4c8d5..dd4b80a 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -116,7 +116,7 @@ static unsigned long get_timestamp(int this_cpu)
> return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
> }
>
> -static unsigned long get_sample_period(void)
> +static u64 get_sample_period(void)
> {
> /*
> * convert watchdog_thresh from seconds to ns
> @@ -125,7 +125,7 @@ static unsigned long get_sample_period(void)
> * and hard thresholds) to increment before the
> * hardlockup detector generates a warning
> */
> - return get_softlockup_thresh() * (NSEC_PER_SEC / 5);
> + return get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
> }
>
> /* Commands for resetting the watchdog */
> --
> 1.7.0.4
>
>
>