From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Sat, 13 Jul 2013 15:10:18 +0000 (+0200)
Subject: vtime: Fix racy cputime delta update
X-Git-Tag: v3.12-rc1~159^2~1^2~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=54461562c90e0ac104764c5a9de637fd9151a1c1;p=pandora-kernel.git

vtime: Fix racy cputime delta update

get_vtime_delta() must be called under the task vtime_seqlock
with the code that does the cputime accounting flush.

Otherwise the cputime reader can be fooled and run into
a race where it sees the snapshot update but misses the
cputime flush. As a result it can report a cputime that is
way too short.

Fix vtime_account_user() that wasn't complying to that rule.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
---

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