Messages in this thread | | | Date | Wed, 11 May 2011 15:22:18 +0200 | From | Tejun Heo <> | Subject | Re: [PATCH 04/11] ptrace: implement PTRACE_INTERRUPT |
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Hey,
On Wed, May 11, 2011 at 02:23:44PM +0200, Denys Vlasenko wrote: > I understand this. I am trying to understand what feature are you trying > to provide to userland, or what problematic race scenario you are trying > to make resolve-able *in userland* by making "stop" and "cont" > notifications sticky wrt GETSIGINFO. I just don't see this scenario.
If you still don't see how events can get lost, I'm afraid I can't explain any better. You're repeating that exit_code can record the event until it's fetched but it doesn't queue and any trap will overwrite it and debuggers don't have to call GETSIGINFO after each trap - it only has to do so for signal delivery, group stop and INTERRUPT trap. So, it can just look at the exit_code (which doesn't indicate continuation) and let tracee return to userland.
Maybe I'm horribly confused. Oleg, am I?
Thanks.
-- tejun
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