Re: [patch 1/3] Text Edit Lock - i386

Andi Kleen
2007-06-18T23:05:44Z

On Tuesday 19 June 2007 00:52:25 Chuck Ebbert wrote:
> On 06/18/2007 05:58 PM, Mathieu Desnoyers wrote:
> > Interface to use for code patching : uses a mutex to insure mutual edit
> > exclusion and makes sure the page is writable.
> >
> ...
> > +/* Mutex protecting text section modification (dynamic code patching) */
> > +static DEFINE_MUTEX(text_mutex);
> > +
>
> Probably should be a spinlock.
>
> And it just occurred to me, how does smp_alternatives deal with this?
> Is it broken now when the text section is read-only?

The text section is only changed to ro very late, alternative code
runs earlier.

But when you unplug all CPUs to go back to UP I suspect it may break.

-Andi