Re: [PATCH v2] kernel: refactor: shorten has_pending_signals

[Oleg Nesterov <oleg@redhat.com>]

On 05/20, Andrea Calabrese wrote:
>
>  static inline bool has_pending_signals(sigset_t *signal, sigset_t *blocked)
>  {
> -	unsigned long ready;
> -	long i;
> -
> -	switch (_NSIG_WORDS) {
> -	default:
> -		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
> -			ready |= signal->sig[i] &~ blocked->sig[i];
> -		break;
> -
> -	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
> -		ready |= signal->sig[2] &~ blocked->sig[2];
> -		ready |= signal->sig[1] &~ blocked->sig[1];
> -		ready |= signal->sig[0] &~ blocked->sig[0];
> -		break;
> -
> -	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
> -		ready |= signal->sig[0] &~ blocked->sig[0];
> -		break;
> -
> -	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
> -	}
> -	return ready !=	0;
> +	unsigned long ready = 0;
> +	for (long i = 0; i < _NSIG_WORDS; i++)
> +		ready |= signal->sig[i] & ~blocked->sig[i];
> +	return ready != 0;
>  }

Note that with your patch the main loop doesn't stop when ready
becomes != 0...

OK, I guess the modern compilers doesn't need this hint even if
_NSIG_WORDS > 1, so

Acked-by: Oleg Nesterov <oleg@redhat.com>


But since your patch is just a cleanup, you could do

	for (int i = 0; i < _NSIG_WORDS; i++) {
		if (signal->sig[i] & ~blocked->sig[i])
			return true;
	}

	return false;

but this is subjective, I won't insist.

Oleg.