From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Ming Lei <tom.leiming@gmail.com>, Kay Sievers <kay@vrfy.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Johannes Berg <johannes@sipsolutions.net>,
Larry Finger <Larry.Finger@lwfinger.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
systemd-devel@lists.freedesktop.org
Subject: Re: udev 182: response timeout for request_firmware in module_probe path
Date: Mon, 27 Aug 2012 02:04:00 +1000 [thread overview]
Message-ID: <1345997040.5138.1.camel@pasglop> (raw)
In-Reply-To: <20120823174613.0489837d@pyramind.ukuu.org.uk>
On Thu, 2012-08-23 at 17:46 +0100, Alan Cox wrote:
> > IMO, the driver probing path is allowed to sleep, so looks request
> firmware
> > should be allowed inside .probe().
>
> I'm not convinced about that. It can sleep but its holding various
> locks
> in most cases, and it looks like that can end up in a complete heap.
>
> By all means *request* the firmware asynchronously in the probe, but
> there needs to be a seperate method somewhere after the probe to
> finish
> the job once the firmware appears.
Not necessarily enough in the general case, for example some stacks will
cause a driver open to be call back from somewhere within the
register_foo() the driver did to register itself with it's subsystem
inside probe. For example register_framebuffer(), register_netdev(), ...
This is clearly a udev bug :-)
Cheers,
Ben.
next prev parent reply other threads:[~2012-08-26 16:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-21 5:34 udev 182: response timeout for request_firmware in module_probe path Ming Lei
2012-08-23 15:16 ` Ming Lei
2012-08-23 15:31 ` Kay Sievers
2012-08-23 16:04 ` Ming Lei
2012-08-23 16:46 ` Alan Cox
2012-08-23 17:03 ` Ming Lei
2012-08-26 16:04 ` Benjamin Herrenschmidt [this message]
2012-08-25 18:59 ` Linus Torvalds
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