From: Stephen Boyd <sboyd@codeaurora.org>
Date: Mon, 14 Jan 2013 18:50:42 +0000 (+0100)
Subject: ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone
X-Git-Tag: v3.8-rc5~4^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=568dca15aa2a0f4ddee255894ec393a159f13147;p=pandora-kernel.git

ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone

Patrik Kluba reports that the preempt count becomes invalid due
to the preempt_enable() call being unbalanced with a
preempt_disable() call in the vfp assembly routines. This happens
because preempt_enable() and preempt_disable() update preempt
counts under PREEMPT_COUNT=y but the vfp assembly routines do so
under PREEMPT=y. In a configuration where PREEMPT=n and
DEBUG_ATOMIC_SLEEP=y, PREEMPT_COUNT=y and so the preempt_enable()
call in VFP_bounce() keeps subtracting from the preempt count
until it goes negative.

Fix this by always using PREEMPT_COUNT to decided when to update
preempt counts in the ARM assembly code.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reported-by: Patrik Kluba <pkluba@dension.com>
Tested-by: Patrik Kluba <pkluba@dension.com>
Cc: <stable@vger.kernel.org> # 2.6.30
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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