resume from another engine results in loss of singlestep req.

[Oleg Nesterov]

On 08/12, Srikar Dronamraju wrote:
>
> Yes setting QUIESCE in utrace_set_events makes
> it work.

Great.

But please don't forget that engine_b_report_signal() which does

	if (signr == SIGTRAP)
		ret = UTRACE_SINGLESTEP | ...

is not right, please see my previous email about "random" value
in ->si_signo. With your test-case, it could be SIGTRAP just
because it was SIGTRAP when utrace_get_signal() was called after
run.sh does kill -s 5.

And UTRACE_SINGLESTEP above can provoke another SIGTRAP from
syscall_trace_leave().

Oleg.