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Date:      Fri, 15 Apr 2011 12:46:18 -0400
From:      Attilio Rao <attilio@freebsd.org>
To:        Kostik Belousov <kostikbel@gmail.com>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, trasz@freebsd.org, John Baldwin <jhb@freebsd.org>
Subject:   Re: svn commit: r220526 - head/sys/kern
Message-ID:  <BANLkTimCUKTnkNMtbgpi%2Bt6%2BfyYPKc5uEw@mail.gmail.com>
In-Reply-To: <20110415082706.GI48734@deviant.kiev.zoral.com.ua>
References:  <201104101707.p3AH736T054347@svn.freebsd.org> <201104141713.28311.jhb@freebsd.org> <20110415082706.GI48734@deviant.kiev.zoral.com.ua>

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2011/4/15 Kostik Belousov <kostikbel@gmail.com>:
> On Thu, Apr 14, 2011 at 05:13:28PM -0400, John Baldwin wrote:
>> On Sunday, April 10, 2011 1:07:03 pm Konstantin Belousov wrote:
>> > Author: kib
>> > Date: Sun Apr 10 17:07:02 2011
>> > New Revision: 220526
>> > URL: http://svn.freebsd.org/changeset/base/220526
>> >
>> > Log:
>> > =C2=A0 Some callers of proc_reparent() already have the parent process=
 locked.
>> > =C2=A0 Detect the situation and avoid process lock recursion.
>> >
>> > =C2=A0 Reported by: =C2=A0 =C2=A0 =C2=A0Fabian Keil <freebsd-listen fa=
biankeil de>
>> >
>> > Modified:
>> > =C2=A0 head/sys/kern/kern_exit.c
>>
>> Can we instead assert it is always held and fix callers that don't? =C2=
=A0Using
>> locked variables is messy and I'd rather avoid it when possible. =C2=A0W=
e already
>> require the caller to hold other locks for this operation.
>>
> I agree that this is ugly, and proper fix probably would be something els=
e.
> E.g. struct proc could grow another field that holds a pointer to the ucr=
ed
> it is accounted for, and locked with some global lock.

As you already hold allproc_lock the process can't be distructed, then
as I already pointed out to Tomasz, it should alright to just bump the
refcount for cred and pass down, I guess.

Attilio


--=20
Peace can only be achieved by understanding - A. Einstein



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