[PATCH v8 2/6] workqueue: Separate sysfs mutable vs immutable wq attribute sanitizing

[Tvrtko Ursulin <tvrtko.ursulin@igalia.com>]

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@igalia.com>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Chia-I Wu <olv@google.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Tejun Heo <tj@kernel.org>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com> # v1
---
v2:
 * Drop a redundant helper and improve commentary. (Tejun)
---
 kernel/workqueue.c | 47 +++++++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 14b87e972ce9..2f0c3f738c70 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5706,6 +5706,30 @@ static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx)
 	}
 }
 
+/*
+ * Sanitize attributes derived from the workqueue flags and which need to be
+ * enforced on every attribute application.
+ */
+static void
+sanitize_immutable_workqueue_attrs(struct workqueue_struct *wq,
+				   struct workqueue_attrs *attrs)
+{
+	if (wq->flags & __WQ_ORDERED)
+		attrs->ordered = true;
+}
+
+/*
+ * Sanitize attributes derived from the workqueue flags and which need to be
+ * enforced only on workqueue creation.
+ */
+static void
+sanitize_mutable_workqueue_attrs(struct workqueue_struct *wq,
+				 struct workqueue_attrs *attrs)
+{
+	if (wq->flags & WQ_HIGHPRI)
+		attrs->nice = HIGHPRI_NICE_LEVEL;
+}
+
 /* allocate the attrs and pwqs for later installation */
 static struct apply_wqattrs_ctx *
 apply_wqattrs_prepare(struct workqueue_struct *wq,
@@ -5735,6 +5759,7 @@ 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 +5782,7 @@ 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 +5945,6 @@ 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 +5956,11 @@ 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_mutable_workqueue_attrs(wq, attrs);
 	ret = apply_workqueue_attrs_locked(wq, attrs);
 	free_workqueue_attrs(attrs);
 	if (ret)
-- 
2.56.0