[PATCH] kernel/resource: make iomem_resource implicit in release_mem_region_adjustable()

[David Hildenbrand <david@xxxxxxxxxx>]

"mem" in the name already indicates the root, similar to
release_mem_region() and devm_request_mem_region(). Make it implicit.
The only single caller always passes iomem_resource, other parents are
not applicable.

Suggested-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---

Based on next-20200915. Follow up on
        "[PATCH v4 0/8] selective merging of system ram resources" [1]
That's in next-20200915. As noted during review of v2 by Wei [2].

[1] https://lkml.kernel.org/r/20200911103459.10306-1-david@xxxxxxxxxx
[2] https://lkml.kernel.org/r/20200915021012.GC2007@L-31X9LVDL-1304.local

---
 include/linux/ioport.h | 3 +--
 kernel/resource.c      | 5 ++---
 mm/memory_hotplug.c    | 2 +-
 3 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 7e61389dcb01..5135d4b86cd6 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -251,8 +251,7 @@ extern struct resource * __request_region(struct resource *,
 extern void __release_region(struct resource *, resource_size_t,
                                resource_size_t);
 #ifdef CONFIG_MEMORY_HOTREMOVE
-extern void release_mem_region_adjustable(struct resource *, resource_size_t,
-                                         resource_size_t);
+extern void release_mem_region_adjustable(resource_size_t, resource_size_t);
 #endif
 #ifdef CONFIG_MEMORY_HOTPLUG
 extern void merge_system_ram_resource(struct resource *res);
diff --git a/kernel/resource.c b/kernel/resource.c
index 7a91b935f4c2..ca2a666e4317 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1240,7 +1240,6 @@ EXPORT_SYMBOL(__release_region);
 #ifdef CONFIG_MEMORY_HOTREMOVE
 /**
  * release_mem_region_adjustable - release a previously reserved memory region
- * @parent: parent resource descriptor
  * @start: resource start address
  * @size: resource region size
  *
@@ -1258,9 +1257,9 @@ EXPORT_SYMBOL(__release_region);
  *   assumes that all children remain in the lower address entry for
  *   simplicity.  Enhance this logic when necessary.
  */
-void release_mem_region_adjustable(struct resource *parent,
-                                  resource_size_t start, resource_size_t size)
+void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
 {
+       struct resource *parent = &iomem_resource;
        struct resource *new_res = NULL;
        bool alloc_nofail = false;
        struct resource **p;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 553c718226b3..7c5e4744ac51 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1764,7 +1764,7 @@ static int __ref try_remove_memory(int nid, u64 start, 
u64 size)
                memblock_remove(start, size);
        }
 
-       release_mem_region_adjustable(&iomem_resource, start, size);
+       release_mem_region_adjustable(start, size);
 
        try_offline_node(nid);
 
-- 
2.26.2