Re: bit fields && data tearing

Paul E. McKenney
2014-09-05T20:43:12Z

On Fri, Sep 05, 2014 at 01:34:52PM -0700, H. Peter Anvin wrote:
> On 09/05/2014 01:14 PM, Peter Hurley wrote:
> >
> > Here's how I read the two statements.
> >
> > First, the commit message:
> >
> > "It [this commit] documents that CPUs [supported by the Linux kernel]
> > _must provide_ atomic one-byte and two-byte naturally aligned loads and stores."
> >
> > Second, in the body of the document:
> >
> > "The Linux kernel no longer supports pre-EV56 Alpha CPUs, because these
> > older CPUs _do not provide_ atomic one-byte and two-byte loads and stores."
> >
>
> Does this apply in general or only to SMP configurations? I guess
> non-SMP configurations would still have problems if interrupted in the
> wrong place...

And preemption could cause problems, too. So I believe that it needs
to be universal.

Thanx, Paul