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Commit f02c6968 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
Browse files

include/linux/memory.h: implement register_hotmemory_notifier() 



When CONFIG_MEMORY_HOTPLUG=n, we don't want the memory-hotplug notifier
handlers to be included in the .o files, for space reasons.

The existing hotplug_memory_notifier() tries to handle this but testing
with gcc-4.4.4 shows that it doesn't work - the hotplug functions are
still present in the .o files.

So implement a new register_hotmemory_notifier() which is a copy of
register_hotcpu_notifier(), and which actually works as desired.
hotplug_memory_notifier() and register_memory_notifier() callsites
should be converted to use this new register_hotmemory_notifier().

While we're there, let's repair the existing hotplug_memory_notifier():
it simply stomps on the register_memory_notifier() return value, so
well-behaved code cannot check for errors.  Apparently non of the
existing callers were well-behaved :(

Cc: Andrew Shewmaker <agshew@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f9d531b8

include/linux/memory.h

+10 −4
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/node.h>

#include <linux/compiler.h>

#include <linux/mutex.h>

#include <linux/notifier.h>



#define MIN_MEMORY_BLOCK_SIZE     (1UL << SECTION_SIZE_BITS)
@@ -127,13 +128,18 @@ enum mem_add_context { BOOT, HOTPLUG }; 
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */



#ifdef CONFIG_MEMORY_HOTPLUG

#define hotplug_memory_notifier(fn, pri) {			\

#define hotplug_memory_notifier(fn, pri) ({		\

	static __meminitdata struct notifier_block fn##_mem_nb =\

		{ .notifier_call = fn, .priority = pri };\

	register_memory_notifier(&fn##_mem_nb);			\

}

})

#define register_hotmemory_notifier(nb)		register_memory_notifier(nb)

#define unregister_hotmemory_notifier(nb) 	unregister_memory_notifier(nb)

#else

#define hotplug_memory_notifier(fn, pri) do { } while (0)

#define hotplug_memory_notifier(fn, pri)	(0)

/* These aren't inline functions due to a GCC bug. */

#define register_hotmemory_notifier(nb)    ({ (void)(nb); 0; })

#define unregister_hotmemory_notifier(nb)  ({ (void)(nb); })

#endif



/*

include/linux/notifier.h

+4 −1
Original line number Diff line number Diff line
@@ -47,8 +47,11 @@ 
 * runtime initialization.

 */



typedef	int (*notifier_fn_t)(struct notifier_block *nb,

			unsigned long action, void *data);



struct notifier_block {

	int (*notifier_call)(struct notifier_block *, unsigned long, void *);

	notifier_fn_t notifier_call;

	struct notifier_block __rcu *next;

	int priority;

};