linux-kernel - [PATCH 5/7] resource: Handle simple alignment inside __find_empty_resource

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Message-Id: <20231222122901.49538-6-ilpo.jarvinen@linux.intel.com>
Date: Fri, 22 Dec 2023 14:28:59 +0200
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: linux-pci@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Igor Mammedov <imammedo@...hat.com>,
	Lukas Wunner <lukas@...ner.de>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@...el.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	linux-kernel@...r.kernel.org
Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 5/7] resource: Handle simple alignment inside __find_empty_resource_slot()

allocate_resource() accepts alignf callback to perform custom alignment
beyond constraint->align. If alignf is NULL, simple_align_resource() is
used which only returns avail->start (no change).

Using avail->start directly is natural and can be done with a
conditional in __find_empty_resource_slot() instead which avoids
unnecessarily using callback. It makes the code inside
__find_empty_resource_slot() more obvious and removes the need for the
caller to provide constraint->alignf unnecessarily.

This is preparation for exporting find_empty_resource_slot().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 kernel/resource.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 9d7920104120..80d64b6467b3 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -563,14 +563,6 @@ void __weak arch_remove_reservations(struct resource *avail)
 {
 }
 
-static resource_size_t simple_align_resource(void *data,
-					     const struct resource *avail,
-					     resource_size_t size,
-					     resource_size_t align)
-{
-	return avail->start;
-}
-
 static void resource_clip(struct resource *res, resource_size_t min,
 			  resource_size_t max)
 {
@@ -590,6 +582,7 @@ static int __find_empty_resource_slot(struct resource *root, struct resource *ol
 {
 	struct resource *this = root->child;
 	struct resource tmp = *new, avail, alloc;
+	resource_alignf alignf = constraint->alignf;
 
 	tmp.start = root->start;
 	/*
@@ -618,8 +611,13 @@ static int __find_empty_resource_slot(struct resource *root, struct resource *ol
 		avail.flags = new->flags & ~IORESOURCE_UNSET;
 		if (avail.start >= tmp.start) {
 			alloc.flags = avail.flags;
-			alloc.start = constraint->alignf(constraint->alignf_data, &avail,
-					size, constraint->align);
+			if (alignf) {
+				alloc.start = alignf(constraint->alignf_data,
+						     &avail, size,
+						     constraint->align);
+			} else {
+				alloc.start = avail.start;
+			}
 			alloc.end = alloc.start + size - 1;
 			if (alloc.start <= alloc.end &&
 			    resource_contains(&avail, &alloc)) {
@@ -730,9 +728,6 @@ int allocate_resource(struct resource *root, struct resource *new,
 	int err;
 	struct resource_constraint constraint;
 
-	if (!alignf)
-		alignf = simple_align_resource;
-
 	constraint.min = min;
 	constraint.max = max;
 	constraint.align = align;
-- 
2.30.2