linux/arch/s390
Ingo Molnar c5905afb0e static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()
So here's a boot tested patch on top of Jason's series that does
all the cleanups I talked about and turns jump labels into a
more intuitive to use facility. It should also address the
various misconceptions and confusions that surround jump labels.

Typical usage scenarios:

        #include <linux/static_key.h>

        struct static_key key = STATIC_KEY_INIT_TRUE;

        if (static_key_false(&key))
                do unlikely code
        else
                do likely code

Or:

        if (static_key_true(&key))
                do likely code
        else
                do unlikely code

The static key is modified via:

        static_key_slow_inc(&key);
        ...
        static_key_slow_dec(&key);

The 'slow' prefix makes it abundantly clear that this is an
expensive operation.

I've updated all in-kernel code to use this everywhere. Note
that I (intentionally) have not pushed through the rename
blindly through to the lowest levels: the actual jump-label
patching arch facility should be named like that, so we want to
decouple jump labels from the static-key facility a bit.

On non-jump-label enabled architectures static keys default to
likely()/unlikely() branches.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: a.p.zijlstra@chello.nl
Cc: mathieu.desnoyers@efficios.com
Cc: davem@davemloft.net
Cc: ddaney.cavm@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.hu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-24 10:05:59 +01:00
..
appldata sched/accounting: Change cpustat fields to an array 2011-12-06 09:06:38 +01:00
boot [S390] Remove Kerntypes leftovers 2011-12-27 11:27:12 +01:00
crypto [S390] crypto: avoid MSA3 and MSA4 instructions in ESA mode 2011-11-14 11:19:09 +01:00
hypfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
include/asm static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]() 2012-02-24 10:05:59 +01:00
kernel [S390] cleanup entry point definition 2012-01-18 18:03:41 +01:00
kvm KVM: s390: announce SYNC_MMU 2011-11-17 16:25:52 +02:00
lib [S390] sparse: fix sparse warnings with __user pointers 2011-10-30 15:16:46 +01:00
math-emu s390: change to new flag variable 2011-03-17 14:02:57 +01:00
mm [S390] cleanup trap handling 2011-12-27 11:27:12 +01:00
oprofile Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-06 08:02:58 -08:00
defconfig [S390] defconfig: switch on CONFIG_DEVTMPFS 2011-10-30 15:16:42 +01:00
Kbuild [S390] make arch/s390 subdirectories depend on config option 2011-12-27 11:27:12 +01:00
Kconfig Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2012-01-09 08:11:13 -08:00
Kconfig.debug [S390] Write protect module text and RO data 2011-03-15 17:08:23 +01:00
Makefile [S390] cleanup entry point definition 2012-01-18 18:03:41 +01:00