linux-kernel - Re: [PATCH v3] Make PTRACE_SEIZE set ptrace options specified in 'data'

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Date:	Tue, 13 Sep 2011 10:04:46 +0200
From:	"Indan Zupancic" <indan@....nu>
To:	"Pedro Alves" <pedro@...esourcery.com>
Cc:	"Denys Vlasenko" <vda.linux@...glemail.com>,
	"Denys Vlasenko" <dvlasenk@...hat.com>,
	"Oleg Nesterov" <oleg@...hat.com>, "Tejun Heo" <tj@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] Make PTRACE_SEIZE set ptrace options specified in
 'data'

Hello,

On Sat, September 10, 2011 14:12, Pedro Alves wrote:
>
> I happen to know gdb's code quite well.  ;-)

In that case, could you explain why gdb isn't using WCONTINUED
notifications for selective thread wakeup instead of trying to
achieve the same at group stop time?

Background thread: https://lkml.org/lkml/2011/9/7/294

Basically the only argument against making ptrace not automatically
continue group stopped tasks was that gdb uses that to resume one
thread instead of all. But it does this by letting the tasks hang in
trapped state at group stop notification time, breaking normal group
stops. If it would instead use the group continuation notification,
gdb would never need to directly interfere with group stops.

I find PTRACE_LISTEN an ugly solution to this problem and am searching
for something nicer.

Greetings,

Indan

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