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

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Message-ID: <CACVXFVM2ZFYeJND7nxGhyGU7cG08Hta5qBZMAz+rDhxM1kRWZA@mail.gmail.com>
Date:	Wed, 8 May 2013 23:52:02 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 1/3] firmware: Avoid superfluous usermodehelper lock

On Wed, May 8, 2013 at 2:56 PM, Takashi Iwai <tiwai@...e.de> 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?

Thanks,
--
Ming Lei
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