[PATCH] base memory: introduce CONFIG_MEMORY_DEVICE

[Yisheng Xie]

MEMORY_FAILURE do not depend on SPARSEMEM_MANUAL,
nor MEMORY_HOTPLUG_SPARSE. However, when I tried to use sysfs:
/sys/devices/system/memory/soft_offline_page
/sys/devices/system/memory/hard_offline_page
to test memory failure function with FLATMEM_MANUAL && MEMORY_FAILURE
enabled on arch like i386, it failed for no such sysfs.

To make sysfs soft_offline_page usable once MEMORY_FAILURE is enabled,
this patch introduces CONFIG_MEMORY_DEVICE, and selects it when
MEMORY_FAILURE or MEMORY_HOTPLUG_SPARSE is enabled.

Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
---
 drivers/base/Kconfig   |  3 +++
 drivers/base/Makefile  |  2 +-
 drivers/base/memory.c  | 32 ++++++++++++++++++++++++++++++--
 include/linux/memory.h |  4 ++++
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index fdf44ca..b4eac4e 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -271,6 +271,9 @@ config DMA_CMA
 	  For more information see <include/linux/dma-contiguous.h>.
 	  If unsure, say "n".
 
+config MEMORY_DEVICE
+	def_bool MEMORY_HOTPLUG_SPARSE || MEMORY_FAILURE
+
 if  DMA_CMA
 comment "Default contiguous memory area size:"
 
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 2609ba2..aafe34b 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -13,7 +13,7 @@ obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
 obj-$(CONFIG_ISA_BUS_API)	+= isa.o
 obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
 obj-$(CONFIG_NUMA)	+= node.o
-obj-$(CONFIG_MEMORY_HOTPLUG_SPARSE) += memory.o
+obj-$(CONFIG_MEMORY_DEVICE) += memory.o
 ifeq ($(CONFIG_SYSFS),y)
 obj-$(CONFIG_MODULES)	+= module.o
 endif
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index dc75de9..fb00965 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -25,10 +25,11 @@
 #include <linux/atomic.h>
 #include <asm/uaccess.h>
 
-static DEFINE_MUTEX(mem_sysfs_mutex);
-
 #define MEMORY_CLASS_NAME	"memory"
 
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+static DEFINE_MUTEX(mem_sysfs_mutex);
+
 #define to_memory_block(dev) container_of(dev, struct memory_block, dev)
 
 static int sections_per_block;
@@ -381,6 +382,7 @@ static ssize_t show_phys_device(struct device *dev,
 	struct memory_block *mem = to_memory_block(dev);
 	return sprintf(buf, "%d\n", mem->phys_device);
 }
+#endif
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 static ssize_t show_valid_zones(struct device *dev,
@@ -427,6 +429,7 @@ static ssize_t show_valid_zones(struct device *dev,
 static DEVICE_ATTR(valid_zones, 0444, show_valid_zones, NULL);
 #endif
 
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
 static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
 static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
@@ -474,6 +477,7 @@ store_auto_online_blocks(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(auto_online_blocks, 0644, show_auto_online_blocks,
 		   store_auto_online_blocks);
+#endif
 
 /*
  * Some architectures will have custom drivers to do this, and
@@ -557,6 +561,7 @@ static DEVICE_ATTR(soft_offline_page, S_IWUSR, NULL, store_soft_offline_page);
 static DEVICE_ATTR(hard_offline_page, S_IWUSR, NULL, store_hard_offline_page);
 #endif
 
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 /*
  * Note that phys_device is optional.  It is here to allow for
  * differentiation between which *physical* devices each
@@ -723,6 +728,7 @@ out:
 	mutex_unlock(&mem_sysfs_mutex);
 	return ret;
 }
+#endif
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 static void
@@ -766,11 +772,13 @@ int unregister_memory_section(struct mem_section *section)
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 /* return true if the memory block is offlined, otherwise, return false */
 bool is_memblock_offlined(struct memory_block *mem)
 {
 	return mem->state == MEM_OFFLINE;
 }
+#endif
 
 static struct attribute *memory_root_attrs[] = {
 #ifdef CONFIG_ARCH_MEMORY_PROBE
@@ -782,8 +790,10 @@ static struct attribute *memory_root_attrs[] = {
 	&dev_attr_hard_offline_page.attr,
 #endif
 
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 	&dev_attr_block_size_bytes.attr,
 	&dev_attr_auto_online_blocks.attr,
+#endif
 	NULL
 };
 
@@ -799,6 +809,7 @@ static const struct attribute_group *memory_root_attr_groups[] = {
 /*
  * Initialize the sysfs support for memory devices...
  */
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 int __init memory_dev_init(void)
 {
 	unsigned int i;
@@ -830,3 +841,20 @@ out:
 		printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
 	return ret;
 }
+#else
+static struct bus_type memory_subsys = {
+	.name = MEMORY_CLASS_NAME,
+	.dev_name = MEMORY_CLASS_NAME,
+};
+
+int __init memory_dev_init(void)
+{
+	int ret = 0;
+
+	ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
+
+	if (ret)
+		pr_err("%s() failed: %d\n", __func__, ret);
+	return ret;
+}
+#endif
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 093607f..9fe1089 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -77,10 +77,14 @@ struct mem_section;
 #define IPC_CALLBACK_PRI        10
 
 #ifndef CONFIG_MEMORY_HOTPLUG_SPARSE
+#ifdef CONFIG_MEMORY_DEVICE
+extern int memory_dev_init(void);
+#else
 static inline int memory_dev_init(void)
 {
 	return 0;
 }
+#endif
 static inline int register_memory_notifier(struct notifier_block *nb)
 {
 	return 0;
-- 
1.7.12.4