Re: [PATCH v7 2/4] workqueue: Separate sysfs mutable vs immutable wq attribute sanitizing

[Liviu Dudau]

On Thu, Oct 22, 2026 at 10:38:46AM +0100, Tvrtko Ursulin wrote:
> In preparation for adding more sanitization steps split the current ones
> into ones which are immutable and the ones which can be modified from
> sysfs.
> 
> Point being that the mutable steps must only run on the initial workqueue
> creation, while the immutable properties need to be sanitized every time
> attributes are applied.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
> Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Cc: Bradley Morgan <include@xxxxxxxxx>
> Cc: Chia-I Wu <olv@xxxxxxxxxx>
> Cc: Liviu Dudau <liviu.dudau@xxxxxxx>
> Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
> Cc: Steven Price <steven.price@xxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>

Reviewed-by: Liviu Dudau <liviu.dudau@xxxxxxx>

Best regards,
Liviu

> ---
>  kernel/workqueue.c | 49 ++++++++++++++++++++++++++++------------------
>  1 file changed, 30 insertions(+), 19 deletions(-)
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index d8cf546d853f..c634b20f1874 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -5706,6 +5706,32 @@ static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx)
>  	}
>  }
>  
> +/* Sanitize attributes not modifiable via sysfs. */
> +static void
> +sanitize_immutable_workqueue_attrs(struct workqueue_struct *wq,
> +				   struct workqueue_attrs *attrs)
> +{
> +	if (wq->flags & __WQ_ORDERED)
> +		attrs->ordered = true;
> +}
> +
> +/* Sanitize attributes modifiable via sysfs. */
> +static void
> +sanitize_mutable_workqueue_attrs(struct workqueue_struct *wq,
> +				 struct workqueue_attrs *attrs)
> +{
> +	if (wq->flags & WQ_HIGHPRI)
> +		attrs->nice = HIGHPRI_NICE_LEVEL;
> +}
> +
> +static void
> +sanitize_workqueue_attrs(struct workqueue_struct *wq,
> +				 struct workqueue_attrs *attrs)
> +{
> +	sanitize_immutable_workqueue_attrs(wq, attrs);
> +	sanitize_mutable_workqueue_attrs(wq, attrs);
> +}
> +
>  /* allocate the attrs and pwqs for later installation */
>  static struct apply_wqattrs_ctx *
>  apply_wqattrs_prepare(struct workqueue_struct *wq,
> @@ -5735,6 +5761,7 @@ apply_wqattrs_prepare(struct workqueue_struct *wq,
>  	 * every possible CPU and never falls back, so it has no default.
>  	 */
>  	copy_workqueue_attrs(new_attrs, attrs);
> +	sanitize_immutable_workqueue_attrs(wq, new_attrs);
>  	wqattrs_actualize_cpumask(new_attrs, unbound_cpumask);
>  	cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
>  	if (!(wq->flags & WQ_PERCPU)) {
> @@ -5757,6 +5784,7 @@ apply_wqattrs_prepare(struct workqueue_struct *wq,
>  
>  	/* save the user configured attrs and sanitize it. */
>  	copy_workqueue_attrs(new_attrs, attrs);
> +	sanitize_immutable_workqueue_attrs(wq, new_attrs);
>  	cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
>  	cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
>  	ctx->attrs = new_attrs;
> @@ -5919,24 +5947,6 @@ static void unbound_wq_update_pwq(struct workqueue_struct *wq, int cpu)
>  	put_pwq_unlocked(old_pwq);
>  }
>  
> -/* the attrs @wq asked for, as spelled by its flags */
> -static struct workqueue_attrs *alloc_wq_std_attrs(struct workqueue_struct *wq)
> -{
> -	struct workqueue_attrs *attrs;
> -
> -	attrs = alloc_workqueue_attrs();
> -	if (!attrs)
> -		return NULL;
> -
> -	if (wq->flags & WQ_HIGHPRI)
> -		attrs->nice = HIGHPRI_NICE_LEVEL;
> -
> -	if (wq->flags & __WQ_ORDERED)
> -		attrs->ordered = true;
> -
> -	return attrs;
> -}
> -
>  static int alloc_and_link_pwqs(struct workqueue_struct *wq)
>  {
>  	struct workqueue_attrs *attrs;
> @@ -5948,10 +5958,11 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
>  	if (!wq->cpu_pwq)
>  		goto enomem;
>  
> -	attrs = alloc_wq_std_attrs(wq);
> +	attrs = alloc_workqueue_attrs();
>  	if (!attrs)
>  		goto enomem;
>  
> +	sanitize_workqueue_attrs(wq, attrs);
>  	ret = apply_workqueue_attrs_locked(wq, attrs);
>  	free_workqueue_attrs(attrs);
>  	if (ret)
> -- 
> 2.56.0
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
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