sparsemem: record when a section has a valid mem_map

We have flags to indicate whether a section actually has a valid mem_map
associated with it.  This is never set and we rely solely on the present bit
to indicate a section is valid.  By definition a section is not valid if it
has no mem_map and there is a window during init where the present bit is set
but there is no mem_map, during which pfn_valid() will return true
incorrectly.

Use the existing SECTION_HAS_MEM_MAP flag to indicate the presence of a valid
mem_map.  Switch valid_section{,_nr} and pfn_valid() to this bit.  Add a new
present_section{,_nr} and pfn_present() interfaces for those users who care to
know that a section is going to be valid.

[akpm@linux-foundation.org: coding-syle fixes]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 7a1390cd6aad..c41d0728efe2 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -238,7 +238,7 @@ store_mem_state(struct sys_device *dev, const char *buf, size_t count)
         mem = container_of(dev, struct memory_block, sysdev);
         phys_section_nr = mem->phys_index;
 
-        if (!valid_section_nr(phys_section_nr))
+        if (!present_section_nr(phys_section_nr))
                 goto out;
 
         if (!strncmp(buf, "online", min((int)count, 6)))
@@ -418,7 +418,7 @@ int register_new_memory(struct mem_section *section)
 
 int unregister_memory_section(struct mem_section *section)
 {
-        if (!valid_section(section))
+        if (!present_section(section))
                 return -EINVAL;
 
         return remove_memory_block(0, section, 0);
@@ -443,7 +443,7 @@ int __init memory_dev_init(void)
          * during boot and have been initialized
          */
         for (i = 0; i < NR_MEM_SECTIONS; i++) {
-                if (!valid_section_nr(i))
+                if (!present_section_nr(i))
                         continue;
                 err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE, 0);
                 if (!ret)