From 7cfdbe7272c8fd5ea0bc10ea369dcac94ef8a08c Mon Sep 17 00:00:00 2001 From: Neels Hofmeyr Date: Wed, 6 Feb 2019 01:30:19 +0100 Subject: comments: clarify usage of conn.assignment and .handover scopes Change-Id: I7ef602c3ce086aecbc3ae3ae6d3fd33ad2b9f85c --- include/osmocom/bsc/gsm_data.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h index 867a46c9a..f6c5129c9 100644 --- a/include/osmocom/bsc/gsm_data.h +++ b/include/osmocom/bsc/gsm_data.h @@ -99,6 +99,9 @@ enum subscr_sccp_state { SUBSCR_SCCP_ST_CONNECTED }; +/* Information retrieved during an Assignment Request from the MSC. This is storage of the Assignment instructions + * parsed from the Assignment Request message, to pass on until the gscon and assignment FSMs have decided whether an + * Assignment is actually going to be carried out. Should remain unchanged after initial decoding. */ struct assignment_request { bool aoip; @@ -112,6 +115,9 @@ struct assignment_request { uint16_t s15_s0; }; +/* State of an ongoing Assignment, while the assignment_fsm is still busy. This serves as state separation to keep the + * currently used lchan and gscon unmodified until the outcome of an Assignment is known. If the Assignment fails, this + * state is simply discarded, and the gscon carries on with the original lchan remaining unchanged. */ struct assignment_fsm_data { struct assignment_request req; bool requires_voice_stream; @@ -204,12 +210,17 @@ struct gsm_subscriber_connection { /* back pointers */ struct gsm_network *network; - /* the primary / currently active lchan to the BTS/subscriber */ + /* the primary / currently active lchan to the BTS/subscriber. During Assignment and Handover, separate lchans + * are kept in the .assignment or .handover sub-structs, respectively, so that this lchan remains unaffected + * until Assignment or Handover have actually succeeded. */ struct gsm_lchan *lchan; + /* Only valid during an ongoing Assignment; might be overwritten at any time by a failed Assignment attempt. + * Once an Assignment was successful, all relevant state must be copied out of this sub-struct. */ struct assignment_fsm_data assignment; - /* handover information, if a handover is pending for this conn. */ + /* handover information, if a handover is pending for this conn. Valid only during an ongoing Handover + * operation. If a Handover was successful, all relevant state must be copied out of this sub-struct. */ struct handover ho; /* buffer/cache for classmark of the ME of the subscriber */ -- cgit v1.2.3