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Date: Wed, 13 Oct 2004 14:17:14 -0700 (PDT)
From: Don Lewis <truckman@FreeBSD.org>
To: ssouhlal@FreeBSD.org
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cc: freebsd-arch@FreeBSD.org
Subject: Re: [RFC] sysctl locking
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On 13 Oct, Suleiman Souhlal wrote:
> Hi,
> 
> On Oct 11, 2004, at 3:30 PM, Don Lewis wrote:
>> There seems to be a lot of locking/unlocking overhead in the oid lookup
>> and oid tree manipulation code.  Doing the traversals at each level of
>> the tree without holding a lock for the entire time makes me nervous,
>> though I can't point to any specific problem.  It might be better to
>> just hold a single lock across then entire lookup, insertion, or
>> deletion operation.
> 
> Thanks for your reply! I think you are right. It would also make the 
> locking much simpler. However, there is the problem that sysctl 
> handlers can sleep, so we shouldn't be holding a mutex when calling 
> them..

Unlock the mutex after doing the lookup and getting ownership of the
oid, and before calling the handler.