Re: [PATCH 3/4] mmzone: note that node_size_lock should be manipulatedvia pgdat_resize_lock()

[Cody P Schafer]

On 05/01/2013 03:42 PM, David Rientjes wrote:
> On Wed, 1 May 2013, Cody P Schafer wrote:
>
> > > > Signed-off-by: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
> > >
> > > Nack, pgdat_resize_unlock() is unnecessary if irqs are known to be
> > > disabled.
> >
> > All this patch does is is indicate that rather than using node_size_lock
> > directly (as it won't be around without CONFIG_MEMORY_HOTPLUG), one should use
> > the pgdat_resize_[un]lock() helper macros.
>
> I think that's obvious given the lock is surrounded by
> #ifdef CONFIG_MEMORY_HOTPLUG.  The fact remains that hotplug code need not
> use pgdat_resize_lock() if irqs are disabled.

Obvious how? This comment is the documentation on how to handle locking 
of pg_data_t, and doesn't mention pgdat_resize_lock() at all. Sure, a 
newcomer would probably find pgdat_resize_lock() eventually, even more 
so if they were interested in performance gains from not re-disabling 
local irqs.

I don't see a convincing reason to omit relevant documentation and make 
it more difficult to find the "right" way to do things.

--
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/