linux-kernel - Re: udev breakages - was: Re: Need of an ".async_probe()" type of callback at driver's core - Was: Re: [PATCH] [media] drxk: change it to use request_firmware

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Message-ID: <4a5bbed4-fe95-4feb-b229-4c658f72ac17@email.android.com>
Date:	Wed, 03 Oct 2012 17:10:17 -0400
From:	Andy Walls <awalls@...metrocast.net>
To:	Greg KH <gregkh@...uxfoundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Al Viro <viro@...iv.linux.org.uk>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Ming Lei <ming.lei@...onical.com>, Kay Sievers <kay@...y.org>,
	Lennart Poettering <lennart@...ttering.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kay Sievers <kay@...hat.com>,
	Linux Media Mailing List <linux-media@...r.kernel.org>,
	Michael Krufky <mkrufky@...uxtv.org>,
	Ivan Kalvachev <ikalvachev@...il.com>
Subject: Re: udev breakages - was: Re: Need of an ".async_probe()" type of callback at driver's core - Was: Re: [PATCH] [media] drxk: change it to use request_firmware_nowait()

Greg KH <gregkh@...uxfoundation.org> wrote:

>On Wed, Oct 03, 2012 at 10:32:08AM -0700, Linus Torvalds wrote:
>> On Wed, Oct 3, 2012 at 10:09 AM, Al Viro <viro@...iv.linux.org.uk>
>wrote:
>> >
>> > +       if (!S_ISREG(inode->i_mode))
>> > +               return false;
>> > +       size = i_size_read(inode);
>> >
>> > Probably better to do vfs_getattr() and check mode and size in
>kstat; if
>> > it's sufficiently hot for that to hurt, we are fucked anyway.
>> >
>> > +               file = filp_open(path, O_RDONLY, 0);
>> > +               if (IS_ERR(file))
>> > +                       continue;
>> > +printk("from file '%s' ", path);
>> > +               success = fw_read_file_contents(file, fw);
>> > +               filp_close(file, NULL);
>> >
>> > fput(file), please.  We have enough misuses of filp_close() as it
>is...
>> 
>> Ok, like this?
>
>This looks good to me.  Having udev do firmware loading and tieing it
>to
>the driver model may have not been such a good idea so many years ago.
>Doing it this way makes more sense.
>
>greg k-h
>--
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I agree that not calling out to userspace for firmware load is better.

Here is an old, unresolved bug about Oops on firmware loading race condition

https://bugzilla.kernel.org/show_bug.cgi?id=15294

The firmware loading timeout in the kernel was cleaning things up, just as udev what trying to say "I'm done loading the firmware" via sysfs; and then *boom*.

Regards,
Andy
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