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From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Daniel Forrest <forrest@lmcg.wisc.edu>
Cc: linux-kernel@vger.kernel.org
Subject: Re: lockd hanging
Date: Fri, 26 Apr 2002 10:30:41 +0200	[thread overview]
Message-ID: <E17117p-0002fH-00@charged.uio.no> (raw)
In-Reply-To: <200204112333.SAA22343@radium.lmcg.wisc.edu> <shsk7rd8k9r.fsf@charged.uio.no> <200204242113.QAA29375@radium.lmcg.wisc.edu>

On Wednesday 24. April 2002 23:13, Daniel Forrest wrote:
> The bug I have found is in fs/lockd/svclock.c and is caused by downing
> an already downed semaphore:
>
> ->nlmsvc_lock				calls down(&file->f_sema)

Just exactly what is f_sema protecting? I've looked at the code, and I just 
can't figure out why we need a semaphore there at all.

AFAICS, all we are using them for is to protect the 2 lists f_shares and 
f_blocks in struct nlm_file. Since we are already holding the BKL, I don't 
see why we need an extra lock. (Yes: nlmsvc_delete_block() can sleep, so we 
need to be careful with the loop in nlmsvc_traverse_blocks(), but that is 
trivial to cope with...)


As for calling nlmclnt_lookup_host() in nlmsvc_create_block(). Why not just 
pass the value that we looked up in nlmsvc_proc_lock()?

Cheers,
  Trond

  reply	other threads:[~2002-04-26  8:30 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-04-11 23:33 Daniel Forrest
2002-04-12  7:10 ` Trond Myklebust
2002-04-24 21:13   ` Daniel Forrest
2002-04-26  8:30     ` Trond Myklebust [this message]
2002-04-26 17:25       ` Daniel Forrest

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