From: Rusty Russell <rusty@rustcorp.com.au>
To: Duncan Sands <baldrick@free.fr>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Writable module parameters - should be volatile?
Date: Tue, 14 Sep 2004 03:54:26 +1000 [thread overview]
Message-ID: <1095098065.25641.38.camel@bach> (raw)
In-Reply-To: <200409121357.25915.baldrick@free.fr>
On Sun, 2004-09-12 at 21:57, Duncan Sands wrote:
> I declare a writable module parameter as follows:
>
> static unsigned int num_rcv_urbs = UDSL_DEFAULT_RCV_URBS;
>
> module_param (num_rcv_urbs, uint, S_IRUGO | S_IWUSR);
>
> Shouldn't I declare num_rcv_urbs volatile? Otherwise compiler
> optimizations could (for example) stick it in a register and miss
> any changes made by someone writing to it...
Sure. If it really matters, you're going to need something stronger
than that, eg module_param_call(). For debugging, it's not usually a
problem. For more complex parameters, you usually need locks anyway.
Cheers,
Rusty.
--
Anyone who quotes me in their signature is an idiot -- Rusty Russell
next prev parent reply other threads:[~2004-09-13 17:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-12 11:57 Writable module parameters - should be volatile? Duncan Sands
2004-09-12 12:52 ` Arnd Bergmann
2004-09-13 11:58 ` Duncan Sands
2004-09-13 17:54 ` Rusty Russell [this message]
2004-09-16 19:02 ` Duncan Sands
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