linux-kernel - [PATCH 0/2] jump label: 2.6.38 updates

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Date:	Wed, 5 Jan 2011 10:43:05 -0500
From:	Jason Baron <jbaron@...hat.com>
To:	peterz@...radead.org, mathieu.desnoyers@...ymtl.ca, hpa@...or.com,
	rostedt@...dmis.org, mingo@...e.hu
Cc:	tglx@...utronix.de, andi@...stfloor.org, roland@...hat.com,
	rth@...hat.com, masami.hiramatsu.pt@...achi.com,
	fweisbec@...il.com, avi@...hat.com, davem@...emloft.net,
	sam@...nborg.org, ddaney@...iumnetworks.com,
	michael@...erman.id.au, linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] jump label: 2.6.38 updates

Hi,

The first patch uses the storage space of the jump label key address
as a pointer into the update table. In this way, we can find all
the addresses that need to be updated without hashing.

The second patch introduces:

static __always_inline bool static_branch(struct jump_label_key *key);

instead of the old JUMP_LABEL(key, label) macro.

In this way, jump labels become really easy to use:

Define:

        struct jump_label_key jump_key;

Can be used as:

        if (static_branch(&jump_key))
                do unlikely code

enable/disale via:

        jump_label_enable(&jump_key);
        jump_label_disable(&jump_key);

that's it!

For perf, which also uses jump labels, I've left the reference counting
out of the jump label layer, thus removing the 'jump_label_inc()' and
'jump_label_dec()' interface. Hopefully, this is a more palatable solution.

Thanks to H. Peter Anvin for suggesting the simpler 'static_branch()'
function.

thanks,

-Jason




Jason Baron (2):
  jump label: make enable/disable o(1)
  jump label: introduce unlikely_switch()

 arch/sparc/include/asm/jump_label.h |   25 ++++---
 arch/x86/include/asm/jump_label.h   |   22 ++++---
 arch/x86/kernel/jump_label.c        |    2 +-
 include/linux/dynamic_debug.h       |   24 ++-----
 include/linux/jump_label.h          |   66 ++++++++++--------
 include/linux/jump_label_ref.h      |   36 +++-------
 include/linux/perf_event.h          |   28 ++++----
 include/linux/tracepoint.h          |    8 +--
 kernel/jump_label.c                 |  129 +++++++++++++++++++++++++++--------
 kernel/perf_event.c                 |   24 ++++--
 kernel/tracepoint.c                 |   22 ++----
 11 files changed, 226 insertions(+), 160 deletions(-)

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