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Commit b3438f82 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Add "pure_initcall" for static variable initialization 



This is a quick hack to overcome the fact that SRCU currently does not
allow static initializers, and we need to sometimes initialize those
things before any other initializers (even "core" ones) can do so.

Currently we don't allow this at all for modules, and the only user that
needs is right now is cpufreq. As reported by Thomas Gleixner:

   "Commit b4dfdbb3 ("[PATCH] cpufreq:
    make the transition_notifier chain use SRCU breaks cpu frequency
    notification users, which register the callback > on core_init
    level."

Cc: Thomas Gleixner <tglx@timesys.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andrew Morton <akpm@osdl.org>,
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f44ea623

drivers/cpufreq/cpufreq.c

+1 −1
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ static int __init init_cpufreq_transition_notifier_list(void) 
	srcu_init_notifier_head(&cpufreq_transition_notifier_list);

	return 0;

}

core_initcall(init_cpufreq_transition_notifier_list);

pure_initcall(init_cpufreq_transition_notifier_list);



static LIST_HEAD(cpufreq_governor_list);

static DEFINE_MUTEX (cpufreq_governor_mutex);

include/asm-generic/vmlinux.lds.h

+2 −0
Original line number Diff line number Diff line
@@ -215,6 +215,8 @@ 
		.notes : { *(.note.*) } :note



#define INITCALLS							\

  	*(.initcall0.init)						\

  	*(.initcall0s.init)						\

  	*(.initcall1.init)						\

  	*(.initcall1s.init)						\

  	*(.initcall2.init)						\

include/linux/init.h

+8 −0
Original line number Diff line number Diff line
@@ -93,6 +93,14 @@ extern void setup_arch(char **); 
	static initcall_t __initcall_##fn##id __attribute_used__ \

	__attribute__((__section__(".initcall" level ".init"))) = fn



/*

 * A "pure" initcall has no dependencies on anything else, and purely

 * initializes variables that couldn't be statically initialized.

 *

 * This only exists for built-in code, not for modules.

 */

#define pure_initcall(fn)		__define_initcall("0",fn,1)



#define core_initcall(fn)		__define_initcall("1",fn,1)

#define core_initcall_sync(fn)		__define_initcall("1s",fn,1s)

#define postcore_initcall(fn)		__define_initcall("2",fn,2)