Re: bit fields && data tearing

Paul E. McKenney
2014-09-05T20:09:26Z

On Fri, Sep 05, 2014 at 03:24:35PM -0400, Peter Hurley wrote:
> On 09/05/2014 03:05 PM, Paul E. McKenney wrote:
> > On Fri, Sep 05, 2014 at 02:50:31PM -0400, Peter Hurley wrote:
> >> On 09/05/2014 02:09 PM, Paul E. McKenney wrote:
>
> [cut]
>
> >>> ------------------------------------------------------------------------
> >>>
> >>> documentation: Record limitations of bitfields and small variables
> >>>
> >>> This commit documents the fact that it is not safe to use bitfields as
> >>> shared variables in synchronization algorithms. It also documents that
> >>> CPUs must provide one-byte and two-byte load and store instructions
> >> ^
> >> atomic
> >
> > Here you meant non-atomic? My guess is that you are referring to the
> > fact that you could emulate a one-byte store on pre-EV56 Alpha CPUs
> > using the ll and sc atomic-read-modify-write instructions, correct?
>
> Yes, that's what I meant. I must be tired and am misreading the commit
> message, or misinterpreting it's meaning.

Very good, got it!

Thanx, Paul