+ kernel-resource-allow-region_intersects-users-to-hold-resource_lock.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: kernel/resource: allow region_intersects users to hold resource_lock
has been added to the -mm tree.  Its filename is
     kernel-resource-allow-region_intersects-users-to-hold-resource_lock.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/kernel-resource-allow-region_intersects-users-to-hold-resource_lock.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/kernel-resource-allow-region_intersects-users-to-hold-resource_lock.patch

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------------------------------------------------------
From: Alistair Popple <apopple@nvidia.com>
Subject: kernel/resource: allow region_intersects users to hold resource_lock

Introduce a version of region_intersects() that can be called with the
resource_lock already held. This is used in a future fix to
__request_free_mem_region().

Link: https://lkml.kernel.org/r/20210419070109.4780-1-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Muchun Song <smuchun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/resource.c |   52 ++++++++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 21 deletions(-)

--- a/kernel/resource.c~kernel-resource-allow-region_intersects-users-to-hold-resource_lock
+++ a/kernel/resource.c
@@ -502,6 +502,34 @@ int __weak page_is_ram(unsigned long pfn
 }
 EXPORT_SYMBOL_GPL(page_is_ram);
 
+int __region_intersects(resource_size_t start, size_t size, unsigned long flags,
+			unsigned long desc)
+{
+	struct resource res;
+	int type = 0; int other = 0;
+	struct resource *p;
+
+	res.start = start;
+	res.end = start + size - 1;
+
+	for (p = iomem_resource.child; p ; p = p->sibling) {
+		bool is_type = (((p->flags & flags) == flags) &&
+				((desc == IORES_DESC_NONE) ||
+				 (desc == p->desc)));
+
+		if (resource_overlaps(p, &res))
+			is_type ? type++ : other++;
+	}
+
+	if (type == 0)
+		return REGION_DISJOINT;
+
+	if (other == 0)
+		return REGION_INTERSECTS;
+
+	return REGION_MIXED;
+}
+
 /**
  * region_intersects() - determine intersection of region with known resources
  * @start: region start address
@@ -525,31 +553,13 @@ EXPORT_SYMBOL_GPL(page_is_ram);
 int region_intersects(resource_size_t start, size_t size, unsigned long flags,
 		      unsigned long desc)
 {
-	struct resource res;
-	int type = 0; int other = 0;
-	struct resource *p;
-
-	res.start = start;
-	res.end = start + size - 1;
+	int ret;
 
 	read_lock(&resource_lock);
-	for (p = iomem_resource.child; p ; p = p->sibling) {
-		bool is_type = (((p->flags & flags) == flags) &&
-				((desc == IORES_DESC_NONE) ||
-				 (desc == p->desc)));
-
-		if (resource_overlaps(p, &res))
-			is_type ? type++ : other++;
-	}
+	ret = __region_intersects(start, size, flags, desc);
 	read_unlock(&resource_lock);
 
-	if (type == 0)
-		return REGION_DISJOINT;
-
-	if (other == 0)
-		return REGION_INTERSECTS;
-
-	return REGION_MIXED;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(region_intersects);
 
_

Patches currently in -mm which might be from apopple@nvidia.com are

kernel-resource-allow-region_intersects-users-to-hold-resource_lock.patch
kernel-resource-refactor-__request_region-to-allow-external-locking.patch
kernel-resource-fix-locking-in-request_free_mem_region.patch