Re: Merging ptrace branch into mainline

From: Denys Vlasenko
Date: Fri Jul 22 2011 - 07:41:01 EST

On Fri, Jul 22, 2011 at 12:30 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> Hello,
> Most of the changes that I had on mind when I wrote "Proposal for
> ptrace improvements"[1] seem complete.  The details of course changed
> quite a bit during implementation iterations but AFAICS all the
> features and fixes described in the propsal are now in Oleg's tree
> waiting to be pulled into mainline.  New features are still blocked by
> the DEVEL flag indicating the API is not finalized yet and should be
> used only for developement.
> Remaining issues are
> * Two different modes of trap notification - directly ptrace_notify()
>  and force_sig(SIGTRAP), which makes SIGTRAP special w.r.t. ptrace.

To what cases of ptrace stops is this applicable?

I thought with PTRACE_O_TRACESYSGOOD the problem with SIGTRAP
being special under strace is dealt with: now both user-sent
SIGTRAPs and ones generated by int3 instruction are handled correctly
in current strace git.

Is it about single-stepping? Strace doesn't use PTRACE_SIGLESTEP,
and I didn't have the need yet to familiarize myself with it.
Does it generate SIGTRAP?

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