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@xxxxxxxxxxxxxxxxxx>
---
This is based on v3.11-rc6, not on my previous patchset. However this patch
does apply cleanly on top of it.
drivers/base/memory.c | 127 +++++++++++++++++++++----------------------------
include/linux/memory.h | 13 ++---
2 files changed, 58 insertions(+), 82 deletions(-)
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 2b7813e..577a0ed 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -16,7 +16,6 @@
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/memory.h>
-#include <linux/kobject.h>
#include <linux/memory_hotplug.h>
#include <linux/mm.h>
#include <linux/mutex.h>
@@ -261,9 +260,8 @@ memory_block_action(unsigned long phys_index, unsigned long action, int online_t
return ret;
}
-static int __memory_block_change_state(struct memory_block *mem,
- unsigned long to_state, unsigned long from_state_req,
- int online_type)
+static int memory_block_change_state(struct memory_block *mem,
+ unsigned long to_state, unsigned long from_state_req)
{
int ret = 0;
@@ -273,105 +271,91 @@ static int __memory_block_change_state(struct memory_block *mem,
if (to_state == MEM_OFFLINE)
mem->state = MEM_GOING_OFFLINE;
- ret = memory_block_action(mem->start_section_nr, to_state, online_type);
+ ret = memory_block_action(mem->start_section_nr, to_state,
+ mem->online_type);
+
mem->state = ret ? from_state_req : to_state;
+
return ret;
}
+/* The device lock serializes operations on memory_subsys_[online|offline] */
static int memory_subsys_online(struct device *dev)
{
struct memory_block *mem = container_of(dev, struct memory_block, dev);
int ret;
- mutex_lock(&mem->state_mutex);
+ if (mem->state == MEM_ONLINE)
+ return 0;
- ret = mem->state == MEM_ONLINE ? 0 :
- __memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE,
- ONLINE_KEEP);
+ /*
+ * If we are called from store_mem_state(), online_type will be
+ * set >= 0 Otherwise we were called from the device online
+ * attribute and need to set the online_type.
+ */
+ if (mem->online_type < 0)
+ mem->online_type = ONLINE_KEEP;
+
+ ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
+
+ /* clear online_type */
+ mem->online_type = -1;
- mutex_unlock(&mem->state_mutex);
return ret;
}
static int memory_subsys_offline(struct device *dev)
{
struct memory_block *mem = container_of(dev, struct memory_block, dev);
- int ret;
-
- mutex_lock(&mem->state_mutex);
- ret = mem->state == MEM_OFFLINE ? 0 :
- __memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE, -1);
+ if (mem->state == MEM_OFFLINE)
+ return 0;
- mutex_unlock(&mem->state_mutex);
- return ret;
+ return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
}
-static int __memory_block_change_state_uevent(struct memory_block *mem,
- unsigned long to_state, unsigned long from_state_req,
- int online_type)
-{
- int ret = __memory_block_change_state(mem, to_state, from_state_req,
- online_type);
- if (!ret) {
- switch (mem->state) {
- case MEM_OFFLINE:
- kobject_uevent(&mem->dev.kobj, KOBJ_OFFLINE);
- break;
- case MEM_ONLINE:
- kobject_uevent(&mem->dev.kobj, KOBJ_ONLINE);
- break;
- default:
- break;
- }
- }
- return ret;
-}
-
-static int memory_block_change_state(struct memory_block *mem,
- unsigned long to_state, unsigned long from_state_req,
- int online_type)
-{
- int ret;
-
- mutex_lock(&mem->state_mutex);
- ret = __memory_block_change_state_uevent(mem, to_state, from_state_req,
- online_type);
- mutex_unlock(&mem->state_mutex);
-
- return ret;
-}
static ssize_t
store_mem_state(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct memory_block *mem;
- bool offline;
- int ret = -EINVAL;
+ int ret, online_type;
mem = container_of(dev, struct memory_block, dev);
lock_device_hotplug();
- if (!strncmp(buf, "online_kernel", min_t(int, count, 13))) {
- offline = false;
- ret = memory_block_change_state(mem, MEM_ONLINE,
- MEM_OFFLINE, ONLINE_KERNEL);
- } else if (!strncmp(buf, "online_movable", min_t(int, count, 14))) {
- offline = false;
- ret = memory_block_change_state(mem, MEM_ONLINE,
- MEM_OFFLINE, ONLINE_MOVABLE);
- } else if (!strncmp(buf, "online", min_t(int, count, 6))) {
- offline = false;
- ret = memory_block_change_state(mem, MEM_ONLINE,
- MEM_OFFLINE, ONLINE_KEEP);
- } else if(!strncmp(buf, "offline", min_t(int, count, 7))) {
- offline = true;
- ret = memory_block_change_state(mem, MEM_OFFLINE,
- MEM_ONLINE, -1);
+ if (!strncmp(buf, "online_kernel", min_t(int, count, 13)))
+ online_type = ONLINE_KERNEL;
+ else if (!strncmp(buf, "online_movable", min_t(int, count, 14)))
+ online_type = ONLINE_MOVABLE;
+ else if (!strncmp(buf, "online", min_t(int, count, 6)))
+ online_type = ONLINE_KEEP;
+ else if (!strncmp(buf, "offline", min_t(int, count, 7)))
+ online_type = -1;
+ else
+ return -EINVAL;
+
+ switch (online_type) {
+ case ONLINE_KERNEL:
+ case ONLINE_MOVABLE:
+ case ONLINE_KEEP:
+ /*
+ * mem->online_type is not protected so there can be a
+ * race here. However, when racing online, the first
+ * will succeed and the second will just return as the
+ * block will already be online. The online type
+ * could be either one, but that is expected.
+ */
+ mem->online_type = online_type;
+ ret = device_online(&mem->dev);
+ break;
+ case -1:
+ ret = device_offline(&mem->dev);
+ break;
+ default:
+ ret = -EINVAL; /* should never happen */
}
- if (!ret)
- dev->offline = offline;
unlock_device_hotplug();
@@ -595,7 +579,6 @@ static int init_memory_block(struct memory_block **memory,
mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
mem->state = state;
mem->section_count++;
- mutex_init(&mem->state_mutex);
start_pfn = section_nr_to_pfn(mem->start_section_nr);
mem->phys_device = arch_get_memory_phys_device(start_pfn);
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 85c31a8..5383461 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 *);
--
1.8.3.4
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