[PATCH] simplify do_signal_stop() && utrace_report_jctl() interaction

[Roland McGrath]

> Questions: should I send the change in signal.c to Andrew right now?
> It can be applied separetely, it doesn't break utrace_report_jctl().

Yes, send it now.  It might be best just to send a replacement
for signals-tracehook_notify_jctl-change.patch that rolls this in.
I wouldn't mention particular utrace code in its log message.
Just something like the old log paragraph:

    Tracing needs the siglock here, held from the time TASK_STOPPED was set,
    to avoid potential SIGCONT races if it wants to allow any blocking in its
    tracing hooks.

adjusted appropriately, perhaps:

    Tracing wants to be able to drop and reacquire the siglock here,
    before TASK_STOPPED is set, to avoid potential SIGCONT races if it
    wants to allow any blocking in its tracing hooks.


Thanks,
Roland