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From: Ananth N Mavinakayanahalli <amavin@redhat.com>
To: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
Cc: ananth@in.ibm.com, systemtap@sources.redhat.com,
	Satoshi Oshima <soshima@redhat.com>,
	Hideo Aoki <haoki@redhat.com>,
	sugita@sdl.hitachi.co.jp
Subject: Re: [Patch 2/5][Djprobe]Djprobe Coexist with Kprobes
Date: Mon, 17 Oct 2005 14:28:00 -0000	[thread overview]
Message-ID: <4353B47B.5010401@redhat.com> (raw)
In-Reply-To: <4353AB77.7070509@sdl.hitachi.co.jp>

Masami Hiramatsu wrote:
> Hi, Ananth
> 
> Ananth N Mavinakayanahalli wrote:
> 
>>On Thu, Sep 29, 2005 at 09:59:31PM +0900, Masami Hiramatsu wrote:
> 
> [snip]
> 
>>>+
>>>+	spin_lock(&djprobe_lock);
>>
>>
>>Please use _irqsave/_irqrestore versions at all places.
> 
> 
> I have a question about using spin_lock_irqsave/restore.
> Why it should be used at all places?
> 
> The djprobe_lock is not refered from probe handlers.
> And register/unregister_djprobe() must not be called
> from any interrupt handlers. So, I think it does not
> cause deadlock even if we use simple spin_lock/unlock().

If the lock isn't referred from any handlers, we should be fine.
Remember though that for historical reasons, kprobe handlers run with
interrupts disabled only on i386. I think this is scheduled to change.
We have seen atleast one other bug due to not using the irqsave/restore
versions.

Ananth

  reply	other threads:[~2005-10-17 14:28 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-29 13:01 Masami Hiramatsu
2005-09-29 14:32 ` Ananth N Mavinakayanahalli
2005-10-03  0:36   ` Masami Hiramatsu
2005-10-17 13:47   ` Masami Hiramatsu
2005-10-17 14:28     ` Ananth N Mavinakayanahalli [this message]
2005-10-03 23:29 ` Keshavamurthy Anil S
2005-10-06  2:50   ` Masami Hiramatsu
2005-10-06 19:57     ` Keshavamurthy Anil S
2005-10-13 10:12       ` Masami Hiramatsu
2005-10-19  3:58         ` Keshavamurthy Anil S
2005-10-19 13:30           ` Masami Hiramatsu
2005-10-19 18:26             ` Keshavamurthy Anil S

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