From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 13 May 2009 14:21:38 +0000 (+0200)
Subject: perf_counter: Rework the perf counter disable/enable
X-Git-Tag: v2.6.31-rc1~383^2~276
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9e35ad388bea89f7d6f375af4c0ae98803688666;p=pandora-kernel.git

perf_counter: Rework the perf counter disable/enable

The current disable/enable mechanism is:

	token = hw_perf_save_disable();
	...
	/* do bits */
	...
	hw_perf_restore(token);

This works well, provided that the use nests properly. Except we don't.

x86 NMI/INT throttling has non-nested use of this, breaking things. Therefore
provide a reference counter disable/enable interface, where the first disable
disables the hardware, and the last enable enables the hardware again.

[ Impact: refactor, simplify the PMU disable/enable logic ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

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