Re: calling request_firmware() from module init will not work with recent/future udev versions

From: "John W. Linville" <linville@tuxdriver.com>
To: Kay Sievers <kay.sievers@vrfy.org>
Cc: netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	Tom Gundersen <teg@jklm.no>, Andy Whitcroft <apw@canonical.com>,
	Arend van Spriel <arend@broadcom.com>,
	Larry Finger <Larry.Finger@lwfinger.net>
Subject: Re: calling request_firmware() from module init will not work with recent/future udev versions
Date: Sat, 14 Jan 2012 12:58:37 -0500	[thread overview]
Message-ID: <20120114175837.GA8504@tuxdriver.com> (raw)
In-Reply-To: <CAPXgP11iT9K2KcDCJvw_druf5qdNjs0jLfrbpS7CcYh5vXrz_w@mail.gmail.com>

Kay, thanks for the reports.  Drivers should definitely be loading
firmware at IFF_UP time.

John

On Sat, Jan 14, 2012 at 04:25:23PM +0100, Kay Sievers wrote:
> Hey,
> 
> just a heads-up, when bug reports are coming in now. The kernel log
> might look like a kernel failure, but it's caused by recent userspace
> changes.
> 
> We changed udev to strictly enforce sequence order and dependency
> handling of events. This seems to break some netdev drivers which
> block in modprobe until the firmware from userspace is loaded into the
> driver.
> 
> I think it's out of question, that nothing must block in module init
> and rely on a userspace transaction to be fulfilled to finish the
> init_module() syscall. If userspace is not running properly, nothing
> will work. Built-in drivers and the transition from initramfs to the
> real root can't be handled properly that way.
> 
> These drivers need to be fixed to load their firmware during ifup,
> which would be the most flexible solution. That way, it should also
> work if the driver is built-in, or is loaded from initramfs and no
> firmware is available.
> Alternatively, the firmware request should be able to use the aync
> firmware_request API and not the blocking one.
> 
> We might need to work around that in the current udev for now, but
> these drivers will definitely break in future udev versions.
> Userspace, these days, should not be in charge of papering over
> obvious kernel bugs like this.
> 
> These are the drivers we received bug reports so far. We didn't look
> into any of details of the drivers, but according to the logs, they
> seem to block for 60 seconds in modprobe, when userspace is not
> behaving like expected:
>   bnx2/bnx2-mips-06-6.2.1.fw
>   rtlwifi/rtl8192sefw.bin
>   brcm/bcm43xx-0.fw
> 
> Any help here would be appreciated.
> 
> Thanks,
> Kay
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-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.