lkml.org 
[lkml]   [2014]   [Jan]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] pid: change task_struct::pid to read-only
On 13/12/22, Oleg Nesterov wrote:
> On 12/20, Peter Zijlstra wrote:
> >
> > On Fri, Dec 20, 2013 at 08:01:57PM +0100, Oleg Nesterov wrote:
> > > The only problem is that
> > >
> > > #define ASSIGN_CONST(l, r) (*(typeof(r) *)&(l) = (r))
> > >
> > > obviously can't work in this case ;) We need something more clever.
> >
> > Hmm indeed, C++ has both the const_cast<>() thingy and the template
> > system is powerful enough to actually implement const_cast<>() inside
> > the language.
>
> So, how about
>
> #define CONST_CAST(type, lval) \
> (*({ \
> (void)((type *)0 == &(lval)); \
> (type *)&(lval); \
> })) \
>
> de_thread/copy_process can do
>
> CONST_CAST(pid_t, tsk->pid) = leader->pid;
>
> and if "type" is wrong we have a warning.

Cool. This works very nicely. Thanks for the ideas Oleg!

> Oleg.

- RGB

--
Richard Guy Briggs <rbriggs@redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545


\
 
 \ /
  Last update: 2014-01-24 00:41    [W:0.169 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site