Re: [RFC][PATCH -mm 3/3] PM: Disable _request_firmware before hibernation/suspend
From: Michael-Luke Jones
Date: Sun May 27 2007 - 16:45:49 EST
On 27 May 2007, at 21:31, Rafael J. Wysocki wrote:
From: Rafael J. Wysocki <rjw@xxxxxxx>
Use a hibernation and suspend notifier to disable the firmware
requesting
mechanism before a hibernation/suspend and enable it after the
operation.
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
drivers/base/firmware_class.c | 36 ++++++++++++++++++++++++++++++
++++++
1 file changed, 36 insertions(+)
I don't like this approach, as I feel that the firmware loading
interface should be able to detect if a firmware load request is not
being handled, due to absence of userspace / hotplug handler presence.
Other circumstances in which this can be a problem is during bootup
when request_firmware() calls can be made before userspace is up and
init has run (even in the presence of an initramfs).
(Slightly OT: A particularly nasty race is when an initramfs
userspace is present, but firmware loading cannot occur because init
has not run, so proc hasn't been mounted, so a hotplug event handler
cannot be registered, despite the fact that the firmware is sitting
on the ramdisk mounted correctly...)
In short, a more general solution would be preferred, and preferably
one which allows firmware loading to *actually* occur once userspace
has actually turned up and registered a handler :)
Michael-Luke Jones
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