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Driver core: Introduce offline/online callbacks for memory blocks
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Introduce .offline() and .online() callbacks for memory_subsys
that will allow the generic device_offline() and device_online()
to be used with device objects representing memory blocks.  That,
in turn, allows the ACPI subsystem to use device_offline() to put
removable memory blocks offline, if possible, before removing
memory modules holding them.

The 'online' sysfs attribute of memory block devices will attempt to
put them offline if 0 is written to it and will attempt to apply the
previously used online type when onlining them (i.e. when 1 is
written to it).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
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Rafael J. Wysocki committed May 12, 2013
1 parent e2ff394 commit 4960e05
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Showing 2 changed files with 88 additions and 25 deletions.
112 changes: 87 additions & 25 deletions drivers/base/memory.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,9 +37,14 @@ static inline int base_memory_block_id(int section_nr)
return section_nr / sections_per_block;
}

static int memory_subsys_online(struct device *dev);
static int memory_subsys_offline(struct device *dev);

static struct bus_type memory_subsys = {
.name = MEMORY_CLASS_NAME,
.dev_name = MEMORY_CLASS_NAME,
.online = memory_subsys_online,
.offline = memory_subsys_offline,
};

static BLOCKING_NOTIFIER_HEAD(memory_chain);
Expand Down Expand Up @@ -88,6 +93,7 @@ int register_memory(struct memory_block *memory)
memory->dev.bus = &memory_subsys;
memory->dev.id = memory->start_section_nr / sections_per_block;
memory->dev.release = memory_block_release;
memory->dev.offline = memory->state == MEM_OFFLINE;

error = device_register(&memory->dev);
return error;
Expand Down Expand Up @@ -278,33 +284,70 @@ static int __memory_block_change_state(struct memory_block *mem,
{
int ret = 0;

if (mem->state != from_state_req) {
ret = -EINVAL;
goto out;
}
if (mem->state != from_state_req)
return -EINVAL;

if (to_state == MEM_OFFLINE)
mem->state = MEM_GOING_OFFLINE;

ret = memory_block_action(mem->start_section_nr, to_state, online_type);

if (ret) {
mem->state = from_state_req;
goto out;
} else {
mem->state = to_state;
if (to_state == MEM_ONLINE)
mem->last_online = online_type;
}
return ret;
}

mem->state = to_state;
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;
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);

ret = mem->state == MEM_ONLINE ? 0 :
__memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE,
mem->last_online);

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);

mutex_unlock(&mem->state_mutex);
return ret;
}

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;
}
}
out:
return ret;
}

Expand All @@ -315,8 +358,8 @@ static int memory_block_change_state(struct memory_block *mem,
int ret;

mutex_lock(&mem->state_mutex);
ret = __memory_block_change_state(mem, to_state, from_state_req,
online_type);
ret = __memory_block_change_state_uevent(mem, to_state, from_state_req,
online_type);
mutex_unlock(&mem->state_mutex);

return ret;
Expand All @@ -326,22 +369,34 @@ 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;

mem = container_of(dev, struct memory_block, dev);

if (!strncmp(buf, "online_kernel", min_t(int, count, 13)))
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)))
} 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)))
} 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)))
} else if(!strncmp(buf, "offline", min_t(int, count, 7))) {
offline = true;
ret = memory_block_change_state(mem, MEM_OFFLINE,
MEM_ONLINE, -1);
}
if (!ret)
dev->offline = offline;

unlock_device_hotplug();

if (ret)
return ret;
Expand Down Expand Up @@ -563,6 +618,7 @@ static int init_memory_block(struct memory_block **memory,
base_memory_block_id(scn_nr) * sections_per_block;
mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
mem->state = state;
mem->last_online = ONLINE_KEEP;
mem->section_count++;
mutex_init(&mem->state_mutex);
start_pfn = section_nr_to_pfn(mem->start_section_nr);
Expand Down Expand Up @@ -681,14 +737,20 @@ int unregister_memory_section(struct mem_section *section)

/*
* offline one memory block. If the memory block has been offlined, do nothing.
*
* Call under device_hotplug_lock.
*/
int offline_memory_block(struct memory_block *mem)
{
int ret = 0;

mutex_lock(&mem->state_mutex);
if (mem->state != MEM_OFFLINE)
ret = __memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE, -1);
if (mem->state != MEM_OFFLINE) {
ret = __memory_block_change_state_uevent(mem, MEM_OFFLINE,
MEM_ONLINE, -1);
if (!ret)
mem->dev.offline = true;
}
mutex_unlock(&mem->state_mutex);

return ret;
Expand Down
1 change: 1 addition & 0 deletions include/linux/memory.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ struct memory_block {
unsigned long start_section_nr;
unsigned long end_section_nr;
unsigned long state;
int last_online;
int section_count;

/*
Expand Down

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