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From: Robert Watson <rwatson@FreeBSD.org>
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To: John Baldwin <jhb@freebsd.org>
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Cc: Attilio Rao <attilio@freebsd.org>, Yuri Pankov <yuri.pankov@gmail.com>,
	freebsd-current@freebsd.org, freebsd-fs@freebsd.org, developers@freebsd.org
Subject: Re: reproducible panic with mount_smbfs
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On Mon, 3 Nov 2008, John Baldwin wrote:

>> Yuri, could you please test this fix: 
>> http://www.freebsd.org/~attilio/netsmb.diff
>>
>> and report if it works? You could get a KASSERT running but this is 
>> expected as I want to identify on the callers who passes a malformed 
>> request and fix it.
>
> This allows all smb locks to recurse unlike the original code I think.  It 
> may be better if smb_vclist was initialized with LK_RECURSE, but not all the 
> other smb locks.  Also, in smb_co_addchild() I think you should just replace 
> the existing asserts with appropriate lockmgr_assert() (you could add a 
> smb_co_assert() to preserve the layering) rather than removing assertions 
> altogether.

My general feeling is that the locking in netsmb needs a bit of cleanup, 
updating, etc.  I'm reluctant to change the underlying primitives (as this 
patch does) without first clarifying what's going on in the code a layer or 
two above.

Robert N M Watson
Computer Laboratory
University of Cambridge