Re: complete_all and "forever" completions

[Peter Zijlstra <peterz@infradead.org>]

On Wed, Oct 26, 2016 at 05:42:13PM +0200, Peter Zijlstra wrote:

> Does something like so work?

try_wait_for_completion() would need a similar change.

> ---
>  kernel/sched/completion.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c
> index 8d0f35debf35..5deab9c789df 100644
> --- a/kernel/sched/completion.c
> +++ b/kernel/sched/completion.c
> @@ -51,7 +51,7 @@ void complete_all(struct completion *x)
>  	unsigned long flags;
>  
>  	spin_lock_irqsave(&x->wait.lock, flags);
> -	x->done += UINT_MAX/2;
> +	x->done = UINT_MAX/2;
>  	__wake_up_locked(&x->wait, TASK_NORMAL, 0);
>  	spin_unlock_irqrestore(&x->wait.lock, flags);
>  }
> @@ -79,7 +79,10 @@ do_wait_for_common(struct completion *x,
>  		if (!x->done)
>  			return timeout;
>  	}
> -	x->done--;
> +
> +	if (x->done != UINT_MAX/2)
> +		x->done--;
> +
>  	return timeout ?: 1;
>  }
>