linux-kernel - [PATCH 1/2] memory hotplug: allow to set phys

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Date:	Tue, 9 Mar 2010 18:19:33 +0100
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Hansen <haveblue@...ibm.com>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Gerald Schaefer <gerald.schaefer@...ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: [PATCH 1/2] memory hotplug: allow to set phys_device

From: Heiko Carstens <heiko.carstens@...ibm.com>

/sys/devices/system/memory/memoryX/phys_device is supposed to contain the
number of the physical device that the corresponding piece of memory
belongs to.
In case a physical device should be replaced or taken offline for whatever
reason it is necessary to set all corresponding memory pieces offline.
The current implementation always sets phys_device to '0' and there is
no way or hook to change that. Seems like there was a plan to implement
that but it wasn't finished for whatever reason.

So add a weak function which architectures can override to actually set
the phys_device from within add_memory_block().

Cc: Dave Hansen <haveblue@...ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@...ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Signed-off-by:  Heiko Carstens <heiko.carstens@...ibm.com>
---
 drivers/base/memory.c  |   15 ++++++++++-----
 include/linux/memory.h |    2 ++
 2 files changed, 12 insertions(+), 5 deletions(-)

--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -429,12 +429,16 @@ static inline int memory_fail_init(void)
  * differentiation between which *physical* devices each
  * section belongs to...
  */
+int __weak arch_get_memory_phys_device(unsigned long start_pfn)
+{
+	return 0;
+}
 
 static int add_memory_block(int nid, struct mem_section *section,
-			unsigned long state, int phys_device,
-			enum mem_add_context context)
+			unsigned long state, enum mem_add_context context)
 {
 	struct memory_block *mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+	unsigned long start_pfn;
 	int ret = 0;
 
 	if (!mem)
@@ -443,7 +447,8 @@ static int add_memory_block(int nid, str
 	mem->phys_index = __section_nr(section);
 	mem->state = state;
 	mutex_init(&mem->state_mutex);
-	mem->phys_device = phys_device;
+	start_pfn = section_nr_to_pfn(mem->phys_index);
+	mem->phys_device = arch_get_memory_phys_device(start_pfn);
 
 	ret = register_memory(mem, section);
 	if (!ret)
@@ -515,7 +520,7 @@ int remove_memory_block(unsigned long no
  */
 int register_new_memory(int nid, struct mem_section *section)
 {
-	return add_memory_block(nid, section, MEM_OFFLINE, 0, HOTPLUG);
+	return add_memory_block(nid, section, MEM_OFFLINE, HOTPLUG);
 }
 
 int unregister_memory_section(struct mem_section *section)
@@ -548,7 +553,7 @@ int __init memory_dev_init(void)
 		if (!present_section_nr(i))
 			continue;
 		err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE,
-					0, BOOT);
+				       BOOT);
 		if (!ret)
 			ret = err;
 	}
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -36,6 +36,8 @@ struct memory_block {
 	struct sys_device sysdev;
 };
 
+int arch_get_memory_phys_device(unsigned long start_pfn);
+
 /* These states are exposed to userspace as text strings in sysfs */
 #define	MEM_ONLINE		(1<<0) /* exposed to userspace */
 #define	MEM_GOING_OFFLINE	(1<<1) /* exposed to userspace */
--
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