#13 get_scno should test TCB_INSYSCALL at the beginning

[Jochen Eisinger]

the function get_scno in signal.c should test whether
the scno needs to be updated at the beginning, instead
of just determining it anyway and deciding at the end
whether it needs to be updated or not.

get_scno is invoked when a syscall is entered and when
it's left. When it's entered, we need the scno anyway,
but when it's left we don't need. Even more, when it's
left we might be already in some other context (signal
handler or similar), so we cannot determine it anyway.
Now on some architectures (s390) this may result in a
(failing) attempt to access memory of the traced
process to determine the scno.

and it's more efficient anyway.

see attached patch.

regards
-- jochen

[Jochen Eisinger]

patch against current cvs

[Eugene Syromyatnikov]

Fixed in a9da8cd179bb8cd374164d674828df9aa441402e.