linux-kernel - Re: [PATCH] Make all it87 drivers SMP safe.

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Message-ID: <BANLkTinT1td=kovSFRu=j5-qwHJ7na6v0Q@mail.gmail.com>
Date:	Wed, 6 Apr 2011 14:45:21 -0700
From:	Natarajan Gurumoorthy <natg@...gle.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	Guenter Roeck <guenter.roeck@...csson.com>,
	Jean Delvare <khali@...ux-fr.org>,
	Wim Van Sebroeck <wim@...ana.be>,
	Mike Waychison <mikew@...gle.com>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>
Subject: Re: [PATCH] Make all it87 drivers SMP safe.

Paul,
     Comments are below.

On Wed, Apr 6, 2011 at 2:35 PM, Paul Gortmaker
<paul.gortmaker@...driver.com> wrote:
> On Wed, Apr 6, 2011 at 3:04 AM, Natarajan Gurumoorthy <natg@...gle.com> wrote:
>> Guenter,
>>      Thank you for your feedback. I found an easier way to deal with
>> the it87_lock.c file. I do not need to move it to the driver/misc
>> directory. The easier thing to do was to move the IT87_LOCK entry to
>> the beginning of the drivers/watchdog/Kconfig file. This moves the
>> entry before the "menuconfig WATCHDOG" entry. They use the exact same
>> trick in drivers/misc/Kconfig file. The very first lines of
>> drivers/watchdog/Kconfig file will look something like this:
>
> Is the Kconfig even warranted?  I mean, if there is a shared resource
> and it needs locking, then just apply the locking.   Where is the value
> in adding another Kconfig?
>
The reason we are forced to do this is that all the it87 drivers are
usually modules. We need a global lock that is compiled into the
kernel if one or more of these drivers are selected. If none of them
are specified then the lock is not built into the kernel. The Kconfig
entry that I have put is not human selectable. When any IT87 driver is
selected it will select IT87_LOCK there by compiling the lock into the
kernel.

-- 
Regards
Nat Gurumoorthy AB6SJ
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