linux-kernel - Re: [PATCH] firmware loader: don't cancel _nowait requests when helper is not yet available

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Date:	Sun, 11 Mar 2012 12:56:13 +0100
From:	Kay Sievers <kay.sievers@...y.org>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	Christian Lamparter <chunkeey@...glemail.com>,
	linux-kernel@...r.kernel.org,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	alan@...rguk.ukuu.org.uk, "Rafael J. Wysocki" <rjw@...k.pl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux PM mailing list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] firmware loader: don't cancel _nowait requests when
 helper is not yet available

On Sat, Mar 10, 2012 at 00:36, Greg KH <gregkh@...uxfoundation.org> wrote:
> On Fri, Mar 09, 2012 at 11:30:24PM +0100, Christian Lamparter wrote:
>> This patch fixes a regression which was introduced by:
>> "PM: Print a warning if firmware is requested when tasks are frozen"
>>
>> request_firmware_nowait does not stall in any system resume paths.
>> Therefore, I think it is perfectly save to use request_firmware_nowait
>> from at least the ->complete() callback.
>
> Is there code somewhere in the kernel that wants to do this?  Has commit
> a144c6a broken it somehow that this fix would resolve it?
>
>>
>> Signed-off-by: Christian Lamparter <chunkeey@...glemail.com>
>> ---
>>  drivers/base/firmware_class.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
>> index 6c9387d..017e020 100644
>> --- a/drivers/base/firmware_class.c
>> +++ b/drivers/base/firmware_class.c
>> @@ -535,7 +535,7 @@ static int _request_firmware(const struct firmware **firmware_p,
>>
>>       read_lock_usermodehelper();
>>
>> -     if (WARN_ON(usermodehelper_is_disabled())) {
>> +     if (WARN_ON(usermodehelper_is_disabled() && !(nowait && uevent))) {
>
> What does uevent have to do with things here?

I don't think that the firmware loader should care about the
usermodehelper at all, and that stuff fiddling should just be removed
from the firmware class.

Forking /sbin/hotplug is disabled by default, it is a broken concept,
and it cannot work reliably on today's systems.

Firmware is not loaded by /sbin/hotplug since many years, but by udev
or whatever service handles uevents, like ueventd on android.

Kay
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