memcpy() in swsusp (was: Re: [PATCH 2/2] Fix console handling during suspend/resume)

Rafael J. Wysocki
2006-07-06T13:22:32Z

Hi,

On Thursday 06 July 2006 09:15, Nigel Cunningham wrote:
> On Thursday 06 July 2006 11:52, Nigel Cunningham wrote:
> > On Thursday 06 July 2006 11:15, Pavel Machek wrote:
> > > I have seen that before: Atomic snapshot used fpu copy in some wrong
> > > variants. Symptom was exactly that -- elevated preempt count --
> > > because fpu copy routine elevated it, then copied the task struct.
> > >
> > > But I thought we solved that problem...?
> >
> > We did. We don't use memcpy for precisely that reason. 3DNOW memcpy was one
> > of the problem children. This would be a different creature though,
> > wouldn't it?
>
> Hmm. Aparently we had a parting of ways on this at some point. Memcpy is being
> used by swsusp, and it has been used since before 2.6.12-rc1. (This is when
> doing the atomic copy, not resuming).

Do you mean the one in copy_data_pages()? Indeed, that may be a problem if
the MMU-based memcpy is used.

Pavel, should we fix this?

Rafael