Re: Linux ptrace handling of SIGSTOP

[Daniel Jacobowitz <drow@false.org>]

On Wed, Jun 08, 2005 at 02:34:48PM -0400, Kris Warkentin wrote:
> The Linux documentation for ptrace(PTRACE_CONT, ...., signal) claims 
> that signal will be passed unless it is a SIGSTOP.  I hit a process that 
> I was debugging with a SIGSTOP, gdb of course stops claiming that the 
> process got a SIGSTOP.  I continue and gdb again says that the process 
> was hit with a SIGSTOP.  If I continue a second time, the process 
> actually continues.
> 
> I was debugging child_resume and observed that both times the ptrace was 
> being called with SIGSTOP but the second time the process actually 
> resumes.  This implies to me that the ptrace documentation is not 
> completely correct because it seems that the first SIGSTOP is being 
> delivered.
> 
> Am I missing something?  The reason that I ask is that we're not 
> currently handling SIGSTOP properly in QNX so I'm trying to find out 
> what the expected behaviour should be.  Based on the docs, I would have 
> thought that the continue would just cause it to resume without further 
> interruption.

I don't know - you'd have to ask the kernel developers, i.e. I'm
punting your question to Roland.

-- 
Daniel Jacobowitz
CodeSourcery, LLC