lkml.org 
[lkml]   [2012]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH v2] pstore/ram: no timekeeping calls when unavailable
On Fri, Nov 09, 2012 at 05:26:53PM -0800, Kees Cook wrote:
[....]
> >> @@ -171,7 +171,13 @@ static size_t ramoops_write_kmsg_hdr(struct
> >> persistent_ram_zone *prz)
> >> struct timeval timestamp;
> >> size_t len;
> >>
> >> - do_gettimeofday(&timestamp);
> >> + /* Handle dumping before timekeeping has resumed. */
> >> + if (unlikely(timekeeping_suspended)) {
> >> + timestamp.tv_sec = 0;
> >> + timestamp.tv_usec = 0;
> >> + } else
> >> + do_gettimeofday(&timestamp);
> >> +
> >
> > Would nulling out the timestamp be better done in do_gettimeofday()? That
> > way we don't have to export timekeeping internals and users would get
> > something more sane for this corner case.
>
> Well... I'm not sure. If we don't want to expose the
> timekeeping_suspended variable, maybe we need a function to check
> this? I think it's probably better to find the users of timekeeping
> that could call it when suspended. That's why I figured the BUG was
> there. Very very few things should be attempting to call gettimeofday
> in a place where it might be suspended. As such, it seems like those
> things should be able to determine how to handle it. Maybe not
> everything would be sensible to get back 0s.
>
> In this particular case, I'm fine with removing the BUG and returning
> 0 instead, since that's fine for ramoops. :)

In the lack of agreement on kernel/time/timekeeping.c change, I can't
apply the patch. And personally I tend to agree that doing this workaround
in the pstore code is odd. How about introducing ___do_gettimeofday() that
is safe to call when suspened, and the func would have good kernel doc
comments explaining the purpose of it?

Thanks,
Anton.


\
 
 \ /
  Last update: 2012-11-17 04:41    [W:0.075 / U:0.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site