linux-kernel - [PATCH v1] ACPI: glue: Rearrange find_child

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Date:   Thu, 05 May 2022 20:52:57 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v1] ACPI: glue: Rearrange find_child_checks()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Notice that it is not necessary to evaluate _STA in find_child_checks()
if the device is expected to have children, but there are none, so
move the children check to the front of the function.

Also notice that FIND_CHILD_MIN_SCORE can be returned right away if
_STA is missing, so make the function do so.

Finally, replace the ternary operator in the return statement argument
with an if () and a standalone return which is somewhat easier to
follow.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/glue.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

Index: linux-pm/drivers/acpi/glue.c
===================================================================
--- linux-pm.orig/drivers/acpi/glue.c
+++ linux-pm/drivers/acpi/glue.c
@@ -79,17 +79,17 @@ static struct acpi_bus_type *acpi_get_bu

 static int find_child_checks(struct acpi_device *adev, bool check_children)
 {
-	bool sta_present = true;
 	unsigned long long sta;
 	acpi_status status;

+	if (check_children && list_empty(&adev->children))
+		return -ENODEV;
+
 	status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);
 	if (status == AE_NOT_FOUND)
-		sta_present = false;
-	else if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
-		return -ENODEV;
+		return FIND_CHILD_MIN_SCORE;

-	if (check_children && list_empty(&adev->children))
+	if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
 		return -ENODEV;

 	/*
@@ -99,8 +99,10 @@ static int find_child_checks(struct acpi
 	 * matched going forward.  [This means a second spec violation in a row,
 	 * so whatever we do here is best effort anyway.]
 	 */
-	return sta_present && !adev->pnp.type.platform_id ?
-			FIND_CHILD_MAX_SCORE : FIND_CHILD_MIN_SCORE;
+	if (adev->pnp.type.platform_id)
+		return FIND_CHILD_MIN_SCORE;
+
+	return FIND_CHILD_MAX_SCORE;
 }

 struct acpi_device *acpi_find_child_device(struct acpi_device *parent,