Re: [PATCH 1/3] firmware: Avoid superfluous usermodehelper lock

From: Takashi Iwai
Date: Wed May 08 2013 - 12:37:23 EST


At Wed, 08 May 2013 18:21:11 +0200,
Takashi Iwai wrote:
>
> At Wed, 8 May 2013 23:52:02 +0800,
> Ming Lei wrote:
> >
> > On Wed, May 8, 2013 at 2:56 PM, Takashi Iwai <tiwai@xxxxxxx> wrote:
> > > When a firmware file can be loaded directly, there is no good reason
> > > to lock usermodehelper. It's needed only when the direct fw load
> > > fails and falls back to the user-mode helper.
> >
> > I remembered that we discussed the problem before, :-)
> >
> > Some crazy drivers might call request_firmware inside resume callback
> > (for example, USB devices might be rebind in resume), with
> > usermodehelper_read_lock, we can find the mistake easily and log it.
> >
> > I am wondering if it is good to remove the usermodehelper lock.
> >
> > Could you let us know any benefit to do it?
>
> Well, the question is whether usermodehelper lock is really an
> appropriate stuff for *checking* the availability of direct fs
> access. I find it doesn't fit well any longer, in the situation where
> no actual user-space call is needed. Though, I'm not quite sure which
> lock or flag can be used instead...

In other words, the first patch is no essential part of the fix.
I can revisit the second patch without this one and resend if
preferred.


Takashi
--
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/