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>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

diff --git a/kernel/resource.c b/kernel/resource.c
index 7e00239a023ae2de6ffd91d69e3d6598d6fbdfb8..8faae19f8236ea168fad391806d51837a08f0430 100644 (file)
--- a/kernel/resource.c
+++ b/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);