Re: [PATCH] add function spin_event_timeout()

[Jeremy Fitzhardinge]

Timur Tabi wrote:
> On Fri, Mar 6, 2009 at 7:11 PM, Roland Dreier <rdreier@xxxxxxxxx> wrote:
>   
> >  > The function spin_event_timeout() takes a condition and timeout value
> >  > (in jiffies) as parameters.  It spins until either the condition is true
> >  > or the timeout expires.  It returns non-zero if the condition is true,
> >  > zero otherwise.
> >
> > What's the motivation for this?  Where do you plan to use it?
> >     
>
> I expect it would be useful for drivers that need to wait until a
> specific register has changed its value, but don't want to risk an
> infinite loop if the hardware is not functioning.  For example, to
> replace the while loop and subsequent check in this code:
>   

A jiffy is a really long time to be spinning, let alone liffies plural.  
In this use case are you expecting that the loop will iterate a very 
small number of times before returning, and the timeout case is a very 
unlikely error condition?

   J
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/