linux-kernel - Re: [PATCH] MIPS: OCTEON: make get_system

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Date:	Tue, 22 Jul 2014 13:31:58 +0100
From:	Markos Chandras <Markos.Chandras@...tec.com>
To:	Aaro Koskinen <aaro.koskinen@....com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	David Daney <david.daney@...ium.com>,
	<linux-mips@...ux-mips.org>, <linux-kernel@...r.kernel.org>
CC:	<stable@...r.kernel.org>
Subject: Re: [PATCH] MIPS: OCTEON: make get_system_type() thread-safe

On 07/22/2014 12:51 PM, Aaro Koskinen wrote:
> get_system_type() is not thread-safe on OCTEON. It uses static data,
> also more dangerous issue is that it's calling cvmx_fuse_read_byte()
> every time without any synchronization. Currently it's possible to get
> processes stuck looping forever in kernel simply by launching multiple
> readers of /proc/cpuinfo:
> 
> 	(while true; do cat /proc/cpuinfo > /dev/null; done) &
> 	(while true; do cat /proc/cpuinfo > /dev/null; done) &
> 	...
> 
> Fix by initializing the system type string only once during the early
> boot.
> 
> Signed-off-by: Aaro Koskinen <aaro.koskinen@....com>
> Cc: stable@...r.kernel.org
> ---
>  arch/mips/cavium-octeon/setup.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 

It looks reasonable to me.

Reviewed-by: Markos Chandras <markos.chandras@...tec.com>

-- 
markos
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