[052/166] drivers/base/memory.c: drop section_count

Commit Message

Andrew Morton April 7, 2020, 3:06 a.m. UTC

From: David Hildenbrand <[e-mail]>
Subject: drivers/base/memory.c: drop section_count

Patch series "mm: drop superfluous section checks when onlining/offlining".

Let's drop some superfluous section checks on the onlining/offlining path.

This patch (of 3):

Since commit c5e79ef561b0 ("mm/memory_hotplug.c: don't allow to
online/offline memory blocks with holes") we have a generic check in
offline_pages() that disallows offlining memory blocks with holes.

Memory blocks with missing sections are just another variant of these type
of blocks.  We can stop checking (and especially storing) present
sections.  A proper error message is now printed why offlining failed.

section_count was initially introduced in commit 07681215975e ("Driver
core: Add section count to memory_block struct") in order to detect when
it is okay to remove a memory block.  It was used in commit 26bbe7ef6d5c
("drivers/base/memory.c: prohibit offlining of memory blocks with missing
sections") to disallow offlining memory blocks with missing sections.  As
we refactored creation/removal of memory devices and have a proper check
for holes in place, we can drop the section_count.

This also removes a leftover comment regarding the mem_sysfs_mutex, which
was removed in commit 848e19ad3c33 ("drivers/base/memory.c: drop the
mem_sysfs_mutex").

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: David Hildenbrand <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: "Rafael J. Wysocki" <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Dan Williams <[e-mail]>
Cc: Pavel Tatashin <[e-mail]>
Cc: Anshuman Khandual <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 drivers/base/memory.c  |   17 +++--------------
 include/linux/memory.h |    1 -
 2 files changed, 3 insertions(+), 15 deletions(-)

Patch

--- a/drivers/base/memory.c~drivers-base-memoryc-drop-section_count
+++ a/drivers/base/memory.c
@@ -267,10 +267,6 @@  static int memory_subsys_offline(struct
 	if (mem->state == MEM_OFFLINE)
 		return 0;
 
-	/* Can't offline block with non-present sections */
-	if (mem->section_count != sections_per_block)
-		return -EINVAL;
-
 	return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
 }
 
@@ -627,7 +623,7 @@  static int init_memory_block(struct memo
 
 static int add_memory_block(unsigned long base_section_nr)
 {
-	int ret, section_count = 0;
+	int section_count = 0;
 	struct memory_block *mem;
 	unsigned long nr;
 
@@ -638,12 +634,8 @@  static int add_memory_block(unsigned lon
 
 	if (section_count == 0)
 		return 0;
-	ret = init_memory_block(&mem, base_memory_block_id(base_section_nr),
-				MEM_ONLINE);
-	if (ret)
-		return ret;
-	mem->section_count = section_count;
-	return 0;
+	return init_memory_block(&mem, base_memory_block_id(base_section_nr),
+				 MEM_ONLINE);
 }
 
 static void unregister_memory(struct memory_block *memory)
@@ -679,7 +671,6 @@  int create_memory_block_devices(unsigned
 		ret = init_memory_block(&mem, block_id, MEM_OFFLINE);
 		if (ret)
 			break;
-		mem->section_count = sections_per_block;
 	}
 	if (ret) {
 		end_block_id = block_id;
@@ -688,7 +679,6 @@  int create_memory_block_devices(unsigned
 			mem = find_memory_block_by_id(block_id);
 			if (WARN_ON_ONCE(!mem))
 				continue;
-			mem->section_count = 0;
 			unregister_memory(mem);
 		}
 	}
@@ -717,7 +707,6 @@  void remove_memory_block_devices(unsigne
 		mem = find_memory_block_by_id(block_id);
 		if (WARN_ON_ONCE(!mem))
 			continue;
-		mem->section_count = 0;
 		unregister_memory_block_under_nodes(mem);
 		unregister_memory(mem);
 	}
--- a/include/linux/memory.h~drivers-base-memoryc-drop-section_count
+++ a/include/linux/memory.h
@@ -26,7 +26,6 @@ 
 struct memory_block {
 	unsigned long start_section_nr;
 	unsigned long state;		/* serialized by the dev->lock */
-	int section_count;		/* serialized by mem_sysfs_mutex */
 	int online_type;		/* for passing data to online routine */
 	int phys_device;		/* to which fru does this belong? */
 	struct device dev;