<p>Harald Welte <strong>merged</strong> this change.</p><p><a href="https://gerrit.osmocom.org/9487">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Harald Welte: Looks good to me, approved
Jenkins Builder: Verified
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">doc: add lchan-release.msc<br><br>Change-Id: Ibcf2326cbc5a5f3f249ae15564825c83b5a063c8<br>---<br>M doc/Makefile.am<br>A doc/lchan-release.msc<br>2 files changed, 150 insertions(+), 0 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/doc/Makefile.am b/doc/Makefile.am</span><br><span>index cc2e277..3c8c2e0 100644</span><br><span>--- a/doc/Makefile.am</span><br><span>+++ b/doc/Makefile.am</span><br><span>@@ -5,6 +5,7 @@</span><br><span> msc: \</span><br><span> $(builddir)/handover.png \</span><br><span> $(builddir)/assignment.png \</span><br><span style="color: hsl(120, 100%, 40%);">+ $(builddir)/lchan-release.png \</span><br><span> $(NULL)</span><br><span> </span><br><span> $(builddir)/%.png: $(srcdir)/%.msc</span><br><span>diff --git a/doc/lchan-release.msc b/doc/lchan-release.msc</span><br><span>new file mode 100644</span><br><span>index 0000000..f75b559</span><br><span>--- /dev/null</span><br><span>+++ b/doc/lchan-release.msc</span><br><span>@@ -0,0 +1,149 @@</span><br><span style="color: hsl(120, 100%, 40%);">+msc {</span><br><span style="color: hsl(120, 100%, 40%);">+ hscale=2;</span><br><span style="color: hsl(120, 100%, 40%);">+ ms [label="MS"], bts [label="BTS"], bsc[label="BSC"], bsc_gscon[label="BSC conn FSM"];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ ms note bsc_gscon [label="various lchan release scenarios"];</span><br><span style="color: hsl(120, 100%, 40%);">+ </span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ ms rbox bsc_gscon [label="IF BSC releases, from BSSMAP Clear Request"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="lchan_release() may be called with sacch_deact=true or false.</span><br><span style="color: hsl(120, 100%, 40%);">+ Currently, the only time lchan_release(sacch_deact=true) is invoked is upon BSSMAP Clear</span><br><span style="color: hsl(120, 100%, 40%);">+ Command, i.e. when the MSC instructs to stop using an active lchan.</span><br><span style="color: hsl(120, 100%, 40%);">+ Some error handling code paths however directly invoke</span><br><span style="color: hsl(120, 100%, 40%);">+ rsl_rf_chan_release(error=1, SACCH_DEACTIVATE)."];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ ---;</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc_gscon note bsc_gscon [label="Rx: BSSMAP Clear Request from MSC"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc <- bsc_gscon [label="gsm0808_clear()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan_release(sacch_deact=1)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan->state = LCHAN_S_REL_REQ"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="_lchan_handle_release(sacch_deact=1)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_release_sapis_from(start=1)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="RSL Release Request (Local End)..."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="...for each SAPI, except link_id=0"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ms <= bsc [label="RR Channel Release"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ms note bsc [label="There is no ACK for RR Channel Release"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_deact_sacch()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="RSL Deactivate SACCH"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc abox bsc [label="Start T3109 (net->T3109, t3109_expired())"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="If T3109 expires"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="t3109_expired()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_rf_chan_release(error=1)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="RSL Release Request (Local End)..."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="...for each SAPI, except link_id=0"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan->state = LCHAN_S_REL_REQ"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="RSL RF Channel Release"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ---;</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc rbox bsc [label="continue in the 'Common' part"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="END: 'BSSMAP Clear Request'"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ ms rbox bsc_gscon [label="IF BSC releases, from implicitly unused lchan"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="The BSC may release old unused lchans after Handover, or release lchans</span><br><span style="color: hsl(120, 100%, 40%);">+ after some error condition."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="BSC decides to release an unused lchan"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan_release(sacch_deact=0)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan->state = LCHAN_S_REL_REQ"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="_lchan_handle_release(sacch_deact=0)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="RSL Release Request (Local End)..."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="...for all SAPIs"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ bts note bsc_gscon [linecolor="red",</span><br><span style="color: hsl(120, 100%, 40%);">+ label="There seems to be no timer watching over RSL Release Request!"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ bts => bsc [label="RSL Release Confirm..."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts => bsc [label="...for all SAPIs"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc rbox bsc [label="continue in the 'Common' part"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ---;</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ ms rbox bsc_gscon [label="IF MS releases"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ms => bts [label="DISC"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts => bsc [label="RLL Release Ind..."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts => bsc [label="...for each SAPI"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc rbox bsc [label="continue in the 'Common' part"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ---;</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ ms rbox bsc_gscon [label="Common"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="for each SAPI (?)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts => bsc [label="RLL Release Confirm / RLL Release Ind"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="abis_rsl_rx_rll()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="mark lchan->sapis[link_id] = LCHAN_SAPI_UNUSED"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rll_indication()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="for each bsc_rll_req matching this link_id:</span><br><span style="color: hsl(120, 100%, 40%);">+ disable timer, call cb(BSC_RLLR_IND_REL_IND)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_handle_release()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="IF all SAPIs are unused"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="Stop T3109"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="T3109 was started if the MSC requested the release"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc abox bsc [label="Start T3111 (net->T3111 value, t3111_expired())"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="END: all SAPIs are unused"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc -> bsc_gscon [label="GSCON_EV_RLL_REL_IND (only if RLL Release Ind)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="END: for each SAPI"];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="T3111 expires"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_rf_chan_release()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="Stop T3109"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="[If lchan->state is LCHAN_S_REL_ERR, don't do anything]"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc abox bsc [label="Start lchan->act_timer (4s, lchan_deact_tmr_cb())"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bts <= bsc [label="RSL RF Channel Release"];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="IF lchan->act_timer expires"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan_deact_tmr_cb()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_lchan_mark_broken(): lchan->state = LCHAN_S_BROKEN"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan_free() (see below)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="END: 'lchan->act_timer expires'"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ bts => bsc [label="RSL RF Channel Release ACK"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_rx_rf_chan_rel_ack()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="Stop lchan->act_timer"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="Stop T3111"];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="IF lchan->state == LCHAN_S_BROKEN"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="If an ACK comes in late, for specific BTS models, we may choose to 'repair'</span><br><span style="color: hsl(120, 100%, 40%);">+ the lchan so that it is usable again, by calling do_lchan_free() directly (see below)."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="rsl_rx_rf_chan_rel_ack() exits here and none of below actions happen.</span><br><span style="color: hsl(120, 100%, 40%);">+ The lchan remains LCHAN_S_BROKEN indefinitely."];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="END: lchan->state == LCHAN_S_BROKEN"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="do_lchan_free()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="IF lchan->state == LCHAN_S_REL_ERR"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="If release failed, we take the lchan back into operation after due</span><br><span style="color: hsl(120, 100%, 40%);">+ timeout"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc abox bsc [label="Start lchan->error_timer (T3111+2, error_timeout_cb())"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="do_lchan_free() continues, async:"];</span><br><span style="color: hsl(120, 100%, 40%);">+ ...;</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="error_timeout_cb()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan->state = LCHAN_S_NONE"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="dyn TS: activate PDCH..."];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="ELSE"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan->state = LCHAN_S_NONE"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="END: lchan->state == LCHAN_S_REL_ERR"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan_free()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="IF conn is still associated (and not dyn TS in switchover)"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc -> bsc [label="S_LCHAN_UNEXPECTED_RELEASE"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="handle_release()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="Stop T10"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [linecolor=orange,label="conn->T10 is actually dead code, it is never started.</span><br><span style="color: hsl(120, 100%, 40%);">+ Instead, the conn FSM starts ST_WAIT_ASS_COMPL with a T10 value."];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc -> bsc_gscon [label="GSCON_EV_RR_ASS_FAIL"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc -> bsc_gscon [label="GSCON_EV_TX_SCCP: BSSMAP Clear Request"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="bsc_clear_handover()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="Stop T3103"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="free handover struct"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="lchan->conn = NULL"];</span><br><span style="color: hsl(120, 100%, 40%);">+ --- [label="END: 'conn is still associated'"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="Stop T3101"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc note bsc [label="T3101 is started when sending an RR Immediate Assignment"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc -> bsc [label="S_CHALLOC_FREED"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc -> bsc [label="rll_lchan_signal()"];</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc box bsc [label="for each bsc_rll_req matching this lchan:</span><br><span style="color: hsl(120, 100%, 40%);">+ disable timer, call cb(BSC_RLLR_IND_REL_IND)"];</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/9487">change 9487</a>. 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<div style="display:none"> Gerrit-Project: osmo-bsc </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-MessageType: merged </div>
<div style="display:none"> Gerrit-Change-Id: Ibcf2326cbc5a5f3f249ae15564825c83b5a063c8 </div>
<div style="display:none"> Gerrit-Change-Number: 9487 </div>
<div style="display:none"> Gerrit-PatchSet: 7 </div>
<div style="display:none"> Gerrit-Owner: Neels Hofmeyr <nhofmeyr@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Harald Welte <laforge@gnumonks.org> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>