mm/memory_hotplug: move and simplify walk_memory_blocks()

Let's move walk_memory_blocks() to the place where memory block logic
resides and simplify it.  While at it, add a type for the callback
function.

Link: http://lkml.kernel.org/r/20190614100114.311-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/base/memory.c

@@ -44,6 +44,11 @@ static inline unsigned long pfn_to_block_id(unsigned long pfn)
 	return base_memory_block_id(pfn_to_section_nr(pfn));
 }
 
+static inline unsigned long phys_to_block_id(unsigned long phys)
+{
+	return pfn_to_block_id(PFN_DOWN(phys));
+}
+
 static int memory_subsys_online(struct device *dev);
 static int memory_subsys_offline(struct device *dev);
 
@@ -851,3 +856,40 @@ out:
 		printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
 	return ret;
 }
+
+/**
+ * walk_memory_blocks - walk through all present memory blocks overlapped
+ *			by the range [start, start + size)
+ *
+ * @start: start address of the memory range
+ * @size: size of the memory range
+ * @arg: argument passed to func
+ * @func: callback for each memory section walked
+ *
+ * This function walks through all present memory blocks overlapped by the
+ * range [start, start + size), calling func on each memory block.
+ *
+ * In case func() returns an error, walking is aborted and the error is
+ * returned.
+ */
+int walk_memory_blocks(unsigned long start, unsigned long size,
+		       void *arg, walk_memory_blocks_func_t func)
+{
+	const unsigned long start_block_id = phys_to_block_id(start);
+	const unsigned long end_block_id = phys_to_block_id(start + size - 1);
+	struct memory_block *mem;
+	unsigned long block_id;
+	int ret = 0;
+
+	for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
+		mem = find_memory_block_by_id(block_id, NULL);
+		if (!mem)
+			continue;
+
+		ret = func(mem, arg);
+		put_device(&mem->dev);
+		if (ret)
+			break;
+	}
+	return ret;
+}

include/linux/memory.h

@@ -119,6 +119,9 @@ extern int memory_isolate_notify(unsigned long val, void *v);
 extern struct memory_block *find_memory_block_hinted(struct mem_section *,
 							struct memory_block *);
 extern struct memory_block *find_memory_block(struct mem_section *);
+typedef int (*walk_memory_blocks_func_t)(struct memory_block *, void *);
+extern int walk_memory_blocks(unsigned long start, unsigned long size,
+			      void *arg, walk_memory_blocks_func_t func);
 #define CONFIG_MEM_BLOCK_SIZE	(PAGES_PER_SECTION<<PAGE_SHIFT)
 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 

include/linux/memory_hotplug.h

@@ -340,8 +340,6 @@ static inline void __remove_memory(int nid, u64 start, u64 size) {}
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 extern void __ref free_area_init_core_hotplug(int nid);
-extern int walk_memory_blocks(unsigned long start, unsigned long size,
-		void *arg, int (*func)(struct memory_block *, void *));
 extern int __add_memory(int nid, u64 start, u64 size);
 extern int add_memory(int nid, u64 start, u64 size);
 extern int add_memory_resource(int nid, struct resource *resource);

mm/memory_hotplug.c

@@ -1659,62 +1659,7 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {
 	return __offline_pages(start_pfn, start_pfn + nr_pages);
 }
-#endif /* CONFIG_MEMORY_HOTREMOVE */
 
-/**
- * walk_memory_blocks - walk through all present memory blocks overlapped
- *			by the range [start, start + size)
- *
- * @start: start address of the memory range
- * @size: size of the memory range
- * @arg: argument passed to func
- * @func: callback for each memory block walked
- *
- * This function walks through all present memory blocks overlapped by the
- * range [start, start + size), calling func on each memory block.
- *
- * Returns the return value of func.
- */
-int walk_memory_blocks(unsigned long start, unsigned long size,
-		void *arg, int (*func)(struct memory_block *, void *))
-{
-	const unsigned long start_pfn = PFN_DOWN(start);
-	const unsigned long end_pfn = PFN_UP(start + size - 1);
-	struct memory_block *mem = NULL;
-	struct mem_section *section;
-	unsigned long pfn, section_nr;
-	int ret;
-
-	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
-		section_nr = pfn_to_section_nr(pfn);
-		if (!present_section_nr(section_nr))
-			continue;
-
-		section = __nr_to_section(section_nr);
-		/* same memblock? */
-		if (mem)
-			if ((section_nr >= mem->start_section_nr) &&
-			    (section_nr <= mem->end_section_nr))
-				continue;
-
-		mem = find_memory_block_hinted(section, mem);
-		if (!mem)
-			continue;
-
-		ret = func(mem, arg);
-		if (ret) {
-			kobject_put(&mem->dev.kobj);
-			return ret;
-		}
-	}
-
-	if (mem)
-		kobject_put(&mem->dev.kobj);
-
-	return 0;
-}
-
-#ifdef CONFIG_MEMORY_HOTREMOVE
 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
 {
 	int ret = !is_memblock_offlined(mem);