2019-07-05 08:59:07

by Puranjay Mohan

Subject: [PATCH] Sched: Change type of 'overrun' from int to u64

Callers of hrtimer_forward_now() should save the return value in u64.
function sched_rt_period_timer() stores
it in variable 'overrun' of type int
change type of overrun from int to u64 to solve the issue.

Signed-off-by: Puranjay Mohan <[email protected]>
---
kernel/sched/rt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 1e6b909dca36..f5d3893914f5 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -19,7 +19,7 @@ static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
struct rt_bandwidth *rt_b =
container_of(timer, struct rt_bandwidth, rt_period_timer);
int idle = 0;
- int overrun;
+ u64 overrun;

raw_spin_lock(&rt_b->rt_runtime_lock);
for (;;) {
--
2.21.0

2019-07-05 12:12:18

by Peter Zijlstra

Subject: Re: [PATCH] Sched: Change type of 'overrun' from int to u64

On Fri, Jul 05, 2019 at 02:26:09PM +0530, Puranjay Mohan wrote:
> Callers of hrtimer_forward_now() should save the return value in u64.
> function sched_rt_period_timer() stores
> it in variable 'overrun' of type int
> change type of overrun from int to u64 to solve the issue.

Is there an actual issue? If we've missed _that_ many periods, something
is really buggered.

From a code consistency PoV this patch makes sense, but I don't think
there anything really wrong with the current code.

> Signed-off-by: Puranjay Mohan <[email protected]>
> ---
> kernel/sched/rt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 1e6b909dca36..f5d3893914f5 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -19,7 +19,7 @@ static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
> struct rt_bandwidth *rt_b =
> container_of(timer, struct rt_bandwidth, rt_period_timer);
> int idle = 0;
> - int overrun;
> + u64 overrun;
>
> raw_spin_lock(&rt_b->rt_runtime_lock);
> for (;;) {
> --
> 2.21.0
>