linux-kernel - b43 wireless driver inhibits access to /dev/hwrng

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Message-ID: <20100722225212.GA19361@darkside.kls.lan>
Date:	Fri, 23 Jul 2010 00:52:12 +0200
From:	"Mario 'BitKoenig' Holbe" <Mario.Holbe@...Ilmenau.DE>
To:	linux-kernel@...r.kernel.org
Subject: b43 wireless driver inhibits access to /dev/hwrng

Hello,

the b43 wireless driver inhibits access to /dev/hwrng while the wireless
network interface is down. When the interface is up, /dev/hwrng is
accessible:

	root@...apad ~ # uname -a
	Linux ideapad 2.6.35-rc5-686 #1 SMP Tue Jul 13 16:16:00 UTC 2010 i686 GNU/Linux
	root@...apad ~ # grep name /proc/cpuinfo
	model name	: VIA Nano processor U2250 (1.6GHz Capable)
	root@...apad ~ # lsmod | grep via.rng
	via_rng                 1243  0
	rng_core                2912  2 via_rng,b43
	root@...apad ~ # hexdump -n 10 /dev/hwrng
	0000000 81f2 8497 71bb d900 f89f
	000000a
	root@...apad ~ # ifconfig wlan0 down
	root@...apad ~ # hexdump -n 10 /dev/hwrng
	hexdump: /dev/hwrng: No such device
	root@...apad ~ # ifconfig wlan0 up
	root@...apad ~ # hexdump -n 10 /dev/hwrng
	0000000 86fc 5d33 4dec d97d da7b
	000000a
	root@...apad ~ #

Aside from such a side-effect being heavily unexpected, this effect is
particularly annoying because it renders rngd failing to start at boot
time - especially when using NetworkManager which is usually started
later than the classic ifupdown methods.

I have no idea whether this issue belongs to the b43 driver or to the
rng core.


Thanks for your work & best regards
   Mario
-- 
The only thing to be scared of, son, is tomorrow.
I don't live for tomorrow. Never saw the fun in it.
                       -- Denny Crane, Boston Legal

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