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").

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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>
Link: http://lkml.kernel.org/r/20200127110424.5757-2-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 4086718f6876ff4f3f1e9c897a14985b9bf21299..086997212dbbac5fe259fb6274f94329a1d3d9f8 100644 (file)
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -267,10 +267,6 @@ static int memory_subsys_offline(struct device *dev)
        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 memory_block **memory,
 
 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 long base_section_nr)
 
        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 long start, unsigned long size)
                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 long start, unsigned long size)
                        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(unsigned long start, unsigned long size)
                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);
        }

diff --git a/include/linux/memory.h b/include/linux/memory.h
index 0b8d791b666908d43e828a24de751ef141050d87..439a89e758d87bd8dfde8dc2fbb6821e82dc3c61 100644 (file)
--- a/include/linux/memory.h
+++ b/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;