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

Andrew Morton
2020-04-07T03:06:43Z

From: David Hildenbrand <david@redhat.com>
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/20200127110424.5757-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- 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;
_