linux-kernel - Question on lockdep and sysrq

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Message-ID: <4A1743C5.9020803@candelatech.com>
Date:	Fri, 22 May 2009 17:31:01 -0700
From:	Ben Greear <greearb@...delatech.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Question on lockdep and sysrq - d

Hello!

I'm trying to debug an apparent deadlock in some code I'm
writing.

When I do a sysrq 'd', I get a nice dump of locks (I have lockdep enabled).

However, the output appears to show multiple processes holding the
same locks (rtnl_mutex, for example):

Showing all locks held in the system:
3 locks held by events/11/63:
  #0:  (events){--..}, at: [<ffffffff8104f71e>] run_workqueue+0xb1/0x216
  #1:  ((linkwatch_work).work){--..}, at: [<ffffffff8104f71e>] run_workqueue+0xb1/0x216
  #2:  (rtnl_mutex){--..}, at: [<ffffffff8125def1>] rtnl_lock+0x12/0x14
1 lock held by irqbalance/3360:
  #0:  (rtnl_mutex){--..}, at: [<ffffffff8125def1>] rtnl_lock+0x12/0x14
1 lock held by hald/3605:
  #0:  (rtnl_mutex){--..}, at: [<ffffffff8125def1>] rtnl_lock+0x12/0x14
...

Is this merely showing processes that are blocked on trying to acquire these locks?

If so, is there any way to tell which processes have fully acquired locks v/s
just waiting to acquire them?

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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