Date: Mon, 22 Nov 2004 16:30:21 -0500 (EST)
From: linux-os <linux-os@chaos.analogic.com>
Reply-To: linux-os@analogic.com
To: Arjan van de Ven <arjan@infradead.org>
cc: Justin Thiessen <jthiessen@penguincomputing.com>, greg@kroah.com,
       phil@netroedge.com, khali@linux-fr.org, sensors@Stimpy.netroedge.com,
       linux-kernel@vger.kernel.org
Subject: Re: adm1026 driver port for kernel 2.6.10-rc2  [RE-REVISED DRIVER]
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On Mon, 22 Nov 2004, Arjan van de Ven wrote:

>
>>> this locking construct is rahter awkward; is it possible to refactor the
>>> code such that you can down and up in the same function ?
>>
>> Yes, at the cost of some minor code duplication or the introduction of
>> another variable.  Is that preferable?  Is holding the lock across function
>> calls a Bad Idea?
>
> holding lock across function calls isn't, unlocking in another function
> than you take the lock is.
> For one it makes auditing the code a lot harder.
>

Also, code like:

 	down(&mylock);
 	do_something();
         if(fail) {
             up(&mylock);
             return retval;
         }

... is prone to errors where a lock never gets released on some
corner cases. It's often better to "goto" a common exit point where
the lock is released.


Cheers,
Dick Johnson
Penguin : Linux version 2.6.9 on an i686 machine (5537.79 BogoMips).
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