send NS_POUT_UNBLOCK_ACK before signalling S_NS_UNBLOCK
In gprs_ns_process_msg(), we were dispatching the S_NS_UNBLOCK
signal before sending out the NS_POUT_UNBLOCK_ACK message.
Signal handlers might send messages to the other side, assuming
that NS is now unblocked. However, since such messages will arrive
before the UNBLOCK_ACK message the receiver might discard them.
This problem has been observed with our TTCN3 BSSGP_Emulation
as a peer to osmo-pcu.
This patch makes TTCN3 PCU TC_paging() test pass regardless of
whether the test or osmo-pcu is started first. Before this patch,
this test would only pass if the test was started before osmo-pcu.
A remaining problem is that the test does not yet keep passing
reliably unless osmo-pcu is restarted between test runs.
Change-Id: I3af54a14bb6bcfa167c9a9d9f67835e7f5b9f1bb
Related: OS#2890
Related: OS#2388
diff --git a/src/gb/gprs_ns.c b/src/gb/gprs_ns.c
index 198ead1..0780f2b 100644
--- a/src/gb/gprs_ns.c
+++ b/src/gb/gprs_ns.c
@@ -1413,8 +1413,10 @@
/* Section 7.2: unblocking procedure */
LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS UNBLOCK\n", (*nsvc)->nsei);
ns_mark_unblocked(*nsvc);
- ns_osmo_signal_dispatch(*nsvc, S_NS_UNBLOCK, 0);
rc = gprs_ns_tx_simple(*nsvc, NS_PDUT_UNBLOCK_ACK);
+ if (rc < 0)
+ break;
+ ns_osmo_signal_dispatch(*nsvc, S_NS_UNBLOCK, 0);
break;
case NS_PDUT_UNBLOCK_ACK:
LOGP(DNS, LOGL_INFO, "NSEI=%u Rx NS UNBLOCK ACK\n", (*nsvc)->nsei);