Re: [PATCH v4] introduce macro spin_event_timeout()

[Timur Tabi <timur@freescale.com>]

Grant Likely wrote:

> I typically use something in the form of this pattern on powerpc code
> when I absolutely have to busywait.
>     int end_ts = get_tbl() + some_delay;  /* note that this is signed */
>     while (end_ts - get_tbl() > 0)
>         if (condition)
>             break;

Funny you mention this, because I was just about to implement the same
thing.  Of course, it will be a PowerPC-only function, but I suppose
that's its fate regardless.

> This macro also looks like a tempting unbounded latency tarpit to fall
> into when people start using it in critical regions,  but that goes
> for code using a non-timed-out busywait also.

I can't fix everything!

-- 
Timur Tabi
Linux kernel developer at Freescale