Re: Writable module parameters - should be volatile?

[Rusty Russell]

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

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