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From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	prasanna@in.ibm.com, anil.s.keshavamurthy@intel.com,
	davem@davemloft.net
Subject: Re: [patch 06/10] Text Edit Lock - kprobes architecture independent support
Date: Fri, 7 Sep 2007 15:58:05 +0530	[thread overview]
Message-ID: <20070907102805.GA10389@in.ibm.com> (raw)
In-Reply-To: <20070906200212.399420921@polymtl.ca>

On Thu, Sep 06, 2007 at 04:01:30PM -0400, Mathieu Desnoyers wrote:

<snip>

> @@ -716,8 +720,9 @@ static int __kprobes pre_handler_kretpro
>  				 struct kretprobe_instance, uflist);
>  		ri->rp = rp;
>  		ri->task = current;
> +		kernel_text_lock();
>  		arch_prepare_kretprobe(ri, regs);
> -
> +		kernel_text_unlock();

pre_handler_kretprobe() is run when the entry probe for a retprobed
function is hit and cannot block. You can't take a mutex here.

And why do we need to take the kernel_text_lock() here anyway? All
arch_prepare_kretprobe() does is modify the return address stored either
on stack or a register (arch specific) to the trampoline. We don't
change any kernel text here.

Ananth

  reply	other threads:[~2007-09-07 10:28 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-06 20:01 [patch 00/10] Text Edit Lock for 2.6.23-rc4-mm1 Mathieu Desnoyers
2007-09-06 20:01 ` [patch 01/10] Kprobes - use a mutex to protect the instruction pages list Mathieu Desnoyers
2007-09-06 20:01 ` [patch 02/10] Kprobes - do not use kprobes mutex in arch code Mathieu Desnoyers
2007-09-06 20:01 ` [patch 03/10] Kprobes - declare kprobe_mutex static Mathieu Desnoyers
2007-09-06 20:01 ` [patch 04/10] Text Edit Lock - Architecture Independent Code Mathieu Desnoyers
2007-09-06 20:01 ` [patch 05/10] Text Edit Lock - Alternative code for i386 and x86_64 Mathieu Desnoyers
2007-09-07  6:59   ` Andi Kleen
2007-09-07 14:04     ` Mathieu Desnoyers
2007-09-07 22:35       ` Andi Kleen
2007-09-11 19:59         ` Mathieu Desnoyers
2007-09-07  8:43   ` Ananth N Mavinakayanahalli
2007-09-07 14:09     ` Mathieu Desnoyers
2007-09-06 20:01 ` [patch 06/10] Text Edit Lock - kprobes architecture independent support Mathieu Desnoyers
2007-09-07 10:28   ` Ananth N Mavinakayanahalli [this message]
2007-09-07 14:13     ` Mathieu Desnoyers
2007-09-06 20:01 ` [patch 07/10] Text Edit Lock - kprobes i386 Mathieu Desnoyers
2007-09-06 20:01 ` [patch 08/10] Text Edit Lock - kprobes x86_64 Mathieu Desnoyers
2007-09-06 20:01 ` [patch 09/10] Text Edit Lock - i386 standardize debug rodata Mathieu Desnoyers
2007-09-06 20:01 ` [patch 10/10] Text Edit Lock - x86_64 " Mathieu Desnoyers
  -- strict thread matches above, loose matches on Subject: below --
2007-08-27 15:56 [patch 00/10] Text Edit Lock Mathieu Desnoyers
2007-08-27 15:56 ` [patch 06/10] Text Edit Lock - kprobes architecture independent support Mathieu Desnoyers

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