ACK: [SRU][Bionic][PATCH] sched/fair: Fix -Wunused-but-set-variable warnings

[Khaled Elmously]

On 2019-10-21 11:06:40 , Juerg Haefliger wrote:
> From: Qian Cai <cai at lca.pw>
> 
> BugLink: https://bugs.launchpad.net/bugs/1832151
> 
> Commit:
> 
>    de53fd7aedb1 ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices")
> 
> introduced a few compilation warnings:
> 
>   kernel/sched/fair.c: In function '__refill_cfs_bandwidth_runtime':
>   kernel/sched/fair.c:4365:6: warning: variable 'now' set but not used [-Wunused-but-set-variable]
>   kernel/sched/fair.c: In function 'start_cfs_bandwidth':
>   kernel/sched/fair.c:4992:6: warning: variable 'overrun' set but not used [-Wunused-but-set-variable]
> 
> Also, __refill_cfs_bandwidth_runtime() does no longer update the
> expiration time, so fix the comments accordingly.
> 
> Signed-off-by: Qian Cai <cai at lca.pw>
> Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
> Reviewed-by: Ben Segall <bsegall at google.com>
> Reviewed-by: Dave Chiluk <chiluk+linux at indeed.com>
> Cc: Linus Torvalds <torvalds at linux-foundation.org>
> Cc: Peter Zijlstra <peterz at infradead.org>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: pauld at redhat.com
> Fixes: de53fd7aedb1 ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices")
> Link: https://lkml.kernel.org/r/1566326455-8038-1-git-send-email-cai@lca.pw
> Signed-off-by: Ingo Molnar <mingo at kernel.org>
> (backported from commit 763a9ec06c409dcde2a761aac4bb83ff3938e0b3)
> [juergh: Dropped modifications of start_cfs_bandwidth() (not applicable for
>  Bionic 4.15).]
> Signed-off-by: Juerg Haefliger <juergh at canonical.com>
> ---
>  kernel/sched/fair.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7c797c8c8071..6c5766f9e924 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4429,21 +4429,16 @@ static inline u64 sched_cfs_bandwidth_slice(void)
>  }
>  
>  /*
> - * Replenish runtime according to assigned quota and update expiration time.
> - * We use sched_clock_cpu directly instead of rq->clock to avoid adding
> - * additional synchronization around rq->lock.
> + * Replenish runtime according to assigned quota. We use sched_clock_cpu
> + * directly instead of rq->clock to avoid adding additional synchronization
> + * around rq->lock.
>   *
>   * requires cfs_b->lock
>   */
>  void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
>  {
> -	u64 now;
> -
> -	if (cfs_b->quota == RUNTIME_INF)
> -		return;
> -
> -	now = sched_clock_cpu(smp_processor_id());
> -	cfs_b->runtime = cfs_b->quota;
> +	if (cfs_b->quota != RUNTIME_INF)
> +		cfs_b->runtime = cfs_b->quota;
>  }
>  
>  static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
> -- 
> 2.20.1
> 
>

Thanks for catching that Juerg!
 
Acked-by: Khalid Elmously <khalid.elmously at canonical.com>