Re: [PATCH] ptrace.2: Clarify PTRACE_INTERRUPT, PTRACE_LISTEN and group-stop behavior

[Denys Vlasenko <dvlasenk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 06/20/2013 04:24 PM, Oleg Nesterov wrote:
>> PTRACE_INTERRUPT (since Linux 3.4)
>> Stop a tracee.
>> [*MODIFIED TEXT->**] If the tracee is running in kernel space
>> and PTRACE_SYSCALL is in effect, it will stop with syscall-exit-stop.
> 
> Yes, but this looks a bit confusing. Or perhaps it is just me.
> 
> IOW, it looks as if PTRACE_INTERRUPT has no effect in this case, the
> tracee should report syscall-exit anyway. I do not know how to explain
> this better...

How about this?

"If the tracee is running or sleeping in kernel space
and PTRACE_SYSCALL is in effect, it will return from kernel
and send syscall-exit-stop notification."

I wonder whether we need to add that "The interrupted system call
will be restarted when tracee is restarted" or this is obvious
enough?

> I think it makes sense to mention that a) PTRACE_INTERRUPT is only
> valid if PTRACE_SEIZE was used, and b) this is the only request which
> doesn't need the stopped tracee. (PTRACE_KILL should die)

It is mentioned elsewhere on the man page.
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