Re: [Linux-fbdev-devel] Re: [ACPI] inappropriate use of in_atomic()
From: Benjamin Herrenschmidt
Date: Fri Mar 11 2005 - 19:30:06 EST
On Fri, 2005-03-11 at 16:13 -0800, Andrew Morton wrote:
> (where'd my cc go?)
> Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> wrote:
> > On Fri, 2005-03-11 at 01:46 -0800, Andrew Morton wrote:
> > > Jan Kasprzak <kas@xxxxxxxxxx> wrote:
> > > >
> > > > This may be the cause of
> > > >
> > > > http://bugme.osdl.org/show_bug.cgi?id=4150
> > >
> > > Looks that way, yes.
> > Note that it would be interesting to fix that (I mean the reliability of
> > is_atomic() or an alternative). I agree it's quite bad to rely on that
> > in practice, but there are a few corner cases where it's useful (like
> > oops handling in fbdev's etc...)
> That would require that we increment current->something on every
> spin/read/write_lock and decrement it in unlock, even with !CONFIG_PREEMPT.
> iirc, Anton added an option to do that to the ppc64 build, decoupled from
> CONFIG_PREEMPT (which ppc64 doesn't support).
ppc64 _does_ support PREEMPT nowadays :)
> But it's an appreciable amount of overhead.
Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/