Re: [PATCH 1/1] ptrace: make sure do_wait() won't hang afterPTRACE_ATTACH

From: Pavel Machek
Date: Mon Feb 28 2011 - 01:12:08 EST

On Mon 2011-02-14 10:03:56, Jan Kratochvil wrote:
> On Mon, 14 Feb 2011 00:01:47 +0100, Denys Vlasenko wrote:
> > * sleep runs in nanosleep
> > * SIGSTOP arrives, strace sees it
> > * strace logs it and allows it via ptrace(PTRACE_SYSCALL, ..., SIGSTOP)
> > * sleep process enters group-stop
> The last point breaks the documented behavior of ptrace:
> If data is nonzero and not SIGSTOP, it is interpreted as a signal to
> be delivered to the child; otherwise, no signal is delivered.
> I do not see it would affect gdb. strace will change its behavior when
> SIGSTOP is sent to its tracee although the new behavior may be OK.
> It is more a subject of apps compatibility testing with such a kernel change.

apps compatibility testing?

No, we don't change kernel APIs like that -- those are called

Just make ptrace(PTRACE_SYSCALL_2, ...) with fixed semantics.
(cesky, pictures)
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