drivers: base: use standard device online/offline for state change

There are two ways to set the online/offline state for a memory block:
echo 0|1 > online and echo online|online_kernel|online_movable|offline >
state.

The state attribute can online a memory block with extra data, the
"online type", where the online attribute uses a default online type of
ONLINE_KEEP, same as echo online > state.

Currently there is a state_mutex that provides consistency between the
memory block state and the underlying memory.

The problem is that this code does a lot of things that the common
device layer can do for us, such as the serialization of the
online/offline handlers using the device lock, setting the dev->offline
field, and calling kobject_uevent().

This patch refactors the online/offline code to allow the common
device_[online|offline] functions to be used.  The result is a simpler
and more common code path for the two state setting mechanisms.  It also
removes the state_mutex from the struct memory_block as the memory block
device lock provides the state consistency.

No functional change is intended by this patch.

Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 10 deletions

diff --git a/include/linux/memory.h b/include/linux/memory.h
index 4c89fb0c8f4c..9a6bbf76452d 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -25,16 +25,9 @@
 struct memory_block {
         unsigned long start_section_nr;
         unsigned long end_section_nr;
-        unsigned long state;
-        int section_count;
-
-        /*
-         * This serializes all state change requests.  It isn't
-         * held during creation because the control files are
-         * created long after the critical areas during
-         * initialization.
-         */
-        struct mutex state_mutex;
+        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? */
         void *hw;                       /* optional pointer to fw/hw data */
         int (*phys_callback)(struct memory_block *);