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Date: Thu, 30 Aug 2007 21:30:31 +1200
From: Andrew Thompson <thompsa@FreeBSD.org>
To: Shteryana Shopova <syrinx@FreeBSD.org>
Message-ID: <20070830093031.GA57339@heff.fud.org.nz>
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Cc: bzeeb+freebsd+lor@zabbadoz.net, freebsd-net@freebsd.org
Subject: Re: iwi(4)-related LOR
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On Thu, Aug 30, 2007 at 11:08:38AM +0300, Shteryana Shopova wrote:
> Hi,
> 
> I am getting the following LOR on my notebook -
> 
> iwi0: <Intel(R) PRO/Wireless 2200BG> mem 0xc8400000-0xc8400fff irq 21
> at device 4.0 on pci2
> iwi0: Ethernet address: 00:15:00:28:5c:dc
> iwi0: [ITHREAD]
> iwi0: link state changed to UP
> iwi0: link state changed to DOWN
> iwi0: link state changed to UP
> lock order reversal:
>  1st 0xc427000c ieee80211com (802.11 com lock) @
> /usr/src/sys/net80211/ieee80211_scan.c:523
>  2nd 0xc4271400 iwi0 (network driver) @
> /usr/src/sys/modules/iwi/../../dev/iwi/if_iwi.c:1907
> KDB: stack backtrace:
> db_trace_self_wrapper(c08f94ff,e25d8a90,c066448e,c08fb8a2,c4271400,...)
> at db_trace_self_wrapper+0x26
> kdb_backtrace(c08fb8a2,c4271400,c3d02950,c426e91b,c426e044,...) at
> kdb_backtrace+0x29
> witness_checkorder(c4271400,9,c426e044,773,c0997fb4,...) at
> witness_checkorder+0x6de
> _mtx_lock_flags(c4271400,0,c426e044,773,e25d8b08,...) at _mtx_lock_flags+0xbc
> iwi_start(c3d16800,c42711b4,e25d8bc8,c06ef074,c3d16800,...) at iwi_start+0xae
> if_start(c3d16800,0,c09064a9,17e,e25d8bac,...) at if_start+0x59
> ieee80211_send_nulldata(c43e0000,38,c08faf85,6ce,c427000c) at
> ieee80211_send_nulldata+0x1f4
> 
> That's on a fresh CURRENT (a couple of days old) and the latest
> version of if_iwi.c - $FreeBSD: src/sys/dev/iwi/if_iwi.c,v 1.56
> 2007/08/29 21:52:03$. Any suggestions are welcome.

This one is known and is due to iwi(4) using a single lock rather than a
seperate one for tx like ath does. As far as I know its not serious.

Andrew