Driver core: Introduce offline/online callbacks for memory blocks

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>

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 14f8a69..c8f3b63 100644 (file)
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -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);
@@ -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;
@@ -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;
 }
 
@@ -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;
@@ -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;
@@ -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);
@@ -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;

diff --git a/include/linux/memory.h b/include/linux/memory.h
index 85c31a8..3d53465 100644 (file)
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -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;
 
        /*