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Date: Wed, 2 Mar 2011 16:25:50 +0100
From: Tejun Heo <tj@kernel.org>
To: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Roland McGrath <roland@redhat.com>,
        jan.kratochvil@redhat.com, linux-kernel@vger.kernel.org,
        torvalds@linux-foundation.org, akpm@linux-foundation.org
Subject: Re: [RFC] Proposal for ptrace improvements
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Hey,

On Wed, Mar 02, 2011 at 04:16:50PM +0100, Denys Vlasenko wrote:
> Assuming the program is run under simple debugger which
> resumes execution using PTRACE_CONT(sig) on signal delivery stops,
> with PTRACE_CONT(0) on ptrace stops,
> and doesn't do any PTRACE_CONT on job control stops,
> with your proposal the debugger will see and perform
> the following actions:
> 
> waitpid...
>   <------ kill -STOP 16382
> waitpid returns WSTOPPED, WSTOPSIG = SIGSTOP
> ptrace(PTRACE_GETSIGINFO) doesn't fail (=> it's signal delivery)
> ptrace(PTRACE_CONT, SIGSTOP)
> waitpid returns WSTOPPED, WSTOPSIG = SIGSTOP
> ptrace(PTRACE_GETSIGINFO) fails (=> it's job control stop)
> waitpid...
>   <------ kill -ABRT 16382
> ...debugger doesn't wake up...
>   <------ kill -WINCH 16382
> ...debugger doesn't wake up...
>   <------ kill -CONT 16382
> waitpid returns WSTOPPED, WSTOPSIG = SIGTRAP (it's a ptrace-stop)
> ptrace(PTRACE_CONT, 0)
> waitpid returns WSTOPPED, WSTOPSIG = SIGWINCH
> ptrace(PTRACE_CONT, SIGWINCH)
> waitpid returns WSTOPPED, WSTOPSIG = SIGCONT
> ptrace(PTRACE_CONT, SIGCONT)
> waitpid returns WSTOPPED, WSTOPSIG = SIGABRT
> ptrace(PTRACE_CONT, SIGABRT)
> 
> Correct?

Yeah, seems correct to me.

Thanks.

-- 
tejun
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