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Date:      Thu, 12 Nov 2015 09:44:52 -0800
From:      Pete Wright <pete@nomadlogic.org>
To:        current@freebsd.org
Subject:   LOR in mpr(4)
Message-ID:  <5644D014.4080601@nomadlogic.org>

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Hi All,
Just wanted a sanity check before filing a PR.  I am running r290688 and
am seeing a LOR being triggered in the mpr(4) device:

$ uname -ar
FreeBSD srd0013 11.0-CURRENT FreeBSD 11.0-CURRENT #1 r290688: Wed Nov 11
21:28:26 PST 2015     root@srd0013:/usr/obj/usr/src/sys/GENERIC  amd64

<dmesg snip>
lock order reversal:
 1st 0xfffff8000d26bc60 CAM device lock (CAM device lock) @
/usr/src/sys/cam/cam_xpt.c:784
 2nd 0xfffffe00012811c0 MPR lock (MPR lock) @
/usr/src/sys/cam/cam_xpt.c:2620
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
0xfffffe04608ee890
witness_checkorder() at witness_checkorder+0xe79/frame 0xfffffe04608ee910
__mtx_lock_flags() at __mtx_lock_flags+0xa4/frame 0xfffffe04608ee960
xpt_action_default() at xpt_action_default+0xb6c/frame 0xfffffe04608ee9b0
scsi_scan_bus() at scsi_scan_bus+0x1d5/frame 0xfffffe04608eea20
xpt_scanner_thread() at xpt_scanner_thread+0x15c/frame 0xfffffe04608eea70
fork_exit() at fork_exit+0x84/frame 0xfffffe04608eeab0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe04608eeab0
--- trap 0, rip = 0, rsp = 0, rbp = 0 ---
<snip>

I can file a PR for this as a quick search on my end didn't return any
bugs related to this.  Checking here first to make sure this isn't
already known/expected behavior.

Thanks!
-pete

-- 
Pete Wright
pete@nomadlogic.org
twitter => @nomadlogicLA




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