lkml.org 
[lkml]   [2013]   [Sep]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/4] [RFC] net: Explicitly initialize u64_stats_sync structures for lockdep

* Eric Dumazet <eric.dumazet@gmail.com> wrote:

> On Thu, 2013-09-26 at 11:34 -0700, John Stultz wrote:
> > In order to enable lockdep on seqcount/seqlock structures, we
> > must explicitly initialize any locks.
> >
>
> > diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h
> > index 8da8c4e..c450e11 100644
> > --- a/include/linux/u64_stats_sync.h
> > +++ b/include/linux/u64_stats_sync.h
> > @@ -67,6 +67,13 @@ struct u64_stats_sync {
> > #endif
> > };
> >
> > +
> > +#if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
> > +#define u64_stats_init(syncp) seqcount_init(syncp.seq)
> > +#else
> > +#define u64_stats_init(syncp)
> > +#endif
> > +
>
> I would prefer a function.

C cannot pass along symbolic names, unfortunately, so we are stuck with
1970's tech and the C preprocessor.

There's a way to make such macros look a tiny bit more structured and thus
be more palatable:

#if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
# define u64_stats_init(syncp) seqcount_init(syncp.seq)
#else
# define u64_stats_init(syncp)
#endif

Note, the 'else' branch should probably be:

# define u64_stats_init(syncp) do { } while (0)

Thanks,

Ingo


\
 
 \ /
  Last update: 2013-09-27 08:21    [W:0.061 / U:0.840 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site