Re: [PATCH v2] checkpatch: Check WQ_PERCPU or WQ_UNBOUND presence in alloc_workqueue() users

[Joe Perches <joe@perches.com>]

On Thu, 2026-06-04 at 17:44 +0200, Marco Crivellari wrote:
> The workqueue API introduced a new flag, WQ_PERCPU, that has to be used when
> WQ_UNBOUND is not present. One of these flags must be present, but not
> both of them.
> 
> To limit usage mistakes, emit an ERROR if one of the below condition is met:
> - alloc_workqueue() is called without WQ_PERCPU nor WQ_UNBOUND
> - alloc_workqueue() is called with both WQ_PERCPU and WQ_UNBOUND
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -7804,8 +7804,31 @@ sub process {
>  			ERROR("UNINITIALIZED_PTR_WITH_FREE",
>  			      "pointer '$1' with __free attribute should be initialized\n" . $herecurr);
>  		}
> -	}
>  
> +# check alloc_workqueue() parameters for WQ_PERCPU and WQ_UNBOUND uses
> +		if (defined($stat) &&
> +		  $stat =~ /^[ \+]\s*(?:$Lval\s*=\s*)?((?:devm_)?alloc_workqueue)\s*($balanced_parens)/) {

Align to open paren please

> +
> +			my $func = $1;
> +			my $args = $2;
> +			my $has_percpu = $args =~ /\bWQ_PERCPU\b/;
> +			my $has_unbound = $args =~ /\bWQ_UNBOUND\b/;
> +			my $error_msg;
> +
> +			if ($has_percpu && $has_unbound) {
> +				$error_msg = "$func() should not contain both WQ_PERCPU and WQ_UNBOUND\n";
> +			} elsif (!$has_percpu && !$has_unbound) {
> +				$error_msg = "$func() must specify either WQ_PERCPU or WQ_UNBOUND\n";
> +			}
> +
> +			if (defined($error_msg)) {
> +				my $stmt_cnt = statement_rawlines($stat);
> +				my $herectx = get_stat_here($linenr, $stmt_cnt, $here);
> +				ERROR("ALLOC_WORKQUEUE_FLAGS",
> +				  $error_msg . $herectx);

Align to open paren please

And as there are false positives, this should probably be a WARN