From a8299c44cf278b675677ef81cc08e24be9024eb2 Mon Sep 17 00:00:00 2001
From: Ksawlii <ksawery.blaszczak@proton.me>
Date: Sun, 24 Nov 2024 00:22:55 +0100
Subject: [PATCH] Revert "resource: fix region_intersects() vs
 add_memory_driver_managed()"

This reverts commit 29fa0c88086e60fb520510eece6ad18c615ec080.
---
 kernel/resource.c | 58 +++++++----------------------------------------
 1 file changed, 8 insertions(+), 50 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 1087f33d7..100253d49 100755
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -539,63 +539,21 @@ EXPORT_SYMBOL_GPL(page_is_ram);
 int region_intersects(resource_size_t start, size_t size, unsigned long flags,
 		      unsigned long desc)
 {
-	resource_size_t ostart, oend;
-	int type = 0; int other = 0;
-	struct resource *p, *dp;
-	bool is_type, covered;
 	struct resource res;
+	int type = 0; int other = 0;
+	struct resource *p;
 
 	res.start = start;
 	res.end = start + size - 1;
 
 	read_lock(&resource_lock);
 	for (p = iomem_resource.child; p ; p = p->sibling) {
-		if (!resource_overlaps(p, &res))
-			continue;
-		is_type = (p->flags & flags) == flags &&
-			(desc == IORES_DESC_NONE || desc == p->desc);
-		if (is_type) {
-			type++;
-			continue;
-		}
-		/*
-		 * Continue to search in descendant resources as if the
-		 * matched descendant resources cover some ranges of 'p'.
-		 *
-		 * |------------- "CXL Window 0" ------------|
-		 * |-- "System RAM" --|
-		 *
-		 * will behave similar as the following fake resource
-		 * tree when searching "System RAM".
-		 *
-		 * |-- "System RAM" --||-- "CXL Window 0a" --|
-		 */
-		covered = false;
-		ostart = max(res.start, p->start);
-		oend = min(res.end, p->end);
-		for (dp = p->child; dp; dp = next_resource(dp, false)) {
-			if (!resource_overlaps(dp, &res))
-				continue;
-			is_type = (dp->flags & flags) == flags &&
-				(desc == IORES_DESC_NONE || desc == dp->desc);
-			if (is_type) {
-				type++;
-				/*
-				 * Range from 'ostart' to 'dp->start'
-				 * isn't covered by matched resource.
-				 */
-				if (dp->start > ostart)
-					break;
-				if (dp->end >= oend) {
-					covered = true;
-					break;
-				}
-				/* Remove covered range */
-				ostart = max(ostart, dp->end + 1);
-			}
-		}
-		if (!covered)
-			other++;
+		bool is_type = (((p->flags & flags) == flags) &&
+				((desc == IORES_DESC_NONE) ||
+				 (desc == p->desc)));
+
+		if (resource_overlaps(p, &res))
+			is_type ? type++ : other++;
 	}
 	read_unlock(&resource_lock);