On 03/15, Roland McGrath wrote:
Then we re-do this (well, almost) check under -siglock,
} else if (task_is_stopped(target)) {
if (!(target-utrace_flags UTRACE_EVENT(JCTL)))
utrace-stopped = stopped = true;
}
But this is not nice. Let's
I was wrong, I forgot that tracehook_get_signal() doesn't need JCTL.
Right, that is key.
OK, let's look at utrace_do_stop:
if (task_is_stopped(target)
!(target-utrace_flags UTRACE_EVENT(JCTL))) {
utrace-stopped = 1;
return true;
}
On 03/12, Roland McGrath wrote:
Yep. And utrace_reset() can be called because -stopped == 1.
Right.
Let me explain. Again, let's suppose D attaches engine E to the target T.
T enters utrace_report_jctl() with -stopped == 1.
D calls utrace_set_events(events = 0), this removes JCTL
I'd like to ask you to clarify what utrace-stopped means...
I'm very glad you are looking into this area!
My understanding is: if we see -stopped == true under utrace-lock, then
the target can do nothing interesting from the utrace's pov. The target
should take utrace-lock at least once.
Roland, I left some parts of your message unanswered because I need to think
more about them...
On 03/12, Roland McGrath wrote:
But, if we enter utrace_report_jctl() with -stopped == 1, JCTL can be
already removed from -utrace_flags, exactly because -stopped was true.
I don't follow this.
Yep. And utrace_reset() can be called because -stopped == 1.
Right.
Let me explain. Again, let's suppose D attaches engine E to the target T.
T enters utrace_report_jctl() with -stopped == 1.
D calls utrace_set_events(events = 0), this removes JCTL from E-flags.
D calls, say,
