Change in osmo-bsc[master]: make sure early lchan act failure resets the lchan

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Neels Hofmeyr gerrit-no-reply at lists.osmocom.org
Fri Dec 21 02:02:44 UTC 2018


Hello Jenkins Builder, 

I'd like you to reexamine a change. Please visit

    https://gerrit.osmocom.org/12388

to look at the new patch set (#2).

Change subject: make sure early lchan act failure resets the lchan
......................................................................

make sure early lchan act failure resets the lchan

Fix crash after AMR configuration fails.

The crash is due to an assertion that finds a non-NULL conn in the lchan, when
re-using an lchan that has failed in AMR configuration earlier on. That is
because the AMR config still happens in state UNUSED.

  DCHAN ERROR lchan(0-0-2-TCH_F_TCH_H_PDCH-0)[0x6120000066a0]{UNUSED}: (type=TCH_F) lchan allocation failed in state UNUSED: Can not generate multirate configuration IE
  ...
  DCHAN DEBUG lchan(0-0-2-TCH_F_TCH_H_PDCH-0)[0x6120000066a0]{UNUSED}: (type=TCH_F) After failure handling, already in state UNUSED
  ...
  ...
  DCHAN DEBUG lchan(0-0-2-TCH_F_TCH_H_PDCH-0)[0x6120000066a0]{UNUSED}: Received Event LCHAN_EV_ACTIVATE (lchan_fsm.c:324)
  Assert failed !lchan->conn ../../../../src/osmo-bsc/src/osmo-bsc/lchan_fsm.c:491

The FSM design idea is that when returning to the UNUSED state, all lchan state
is cleared. However, when calling lchan_activate(), a failure may happen still
in state UNUSED, so that we don't transition *back* to UNUSED properly.

So, first transition out of UNUSED before failures can happen. (Other ways to
solve this would be to invoke lchan clearing even if already in UNUSED, but
semantically, transitioning first makes more sense.)

Upon LCHAN_EV_ACTIVATE, just remember the lchan_activate_info and transition to
WAIT_TS_READY, so that on lchan_fail(), we can normally transition back to
UNUSED and clear the lchan.

Move the initial lchan activation code to lchan_fsm_wait_ts_ready_onenter().

Also, there is a bit of duplication of members of the lchan->activate (lchan
state) and the lchan_activate_info (passed to lchan_activate()) structs. The
fix for this also removes the dup:

Add struct lchan_activate_info as child struct at lchan->activate.info, drop
the other lchan->activate members that would dup .info.*. Move struct
lchan_activate_info declaration to gsm_data.h.

Apply the new '.info' member struct throughout the code.

Related: OS#3737
Change-Id: Ide665b10fa3f4583059c55346db8da833959e3cc
---
M include/osmocom/bsc/gsm_data.h
M include/osmocom/bsc/lchan_fsm.h
M src/osmo-bsc/assignment_fsm.c
M src/osmo-bsc/bsc_subscr_conn_fsm.c
M src/osmo-bsc/handover_fsm.c
M src/osmo-bsc/lchan_fsm.c
M src/osmo-bsc/lchan_rtp_fsm.c
M src/osmo-bsc/osmo_bsc_bssap.c
8 files changed, 105 insertions(+), 107 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/88/12388/2
-- 
To view, visit https://gerrit.osmocom.org/12388
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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ide665b10fa3f4583059c55346db8da833959e3cc
Gerrit-Change-Number: 12388
Gerrit-PatchSet: 2
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder (1000002)
Gerrit-Reviewer: Neels Hofmeyr <nhofmeyr at sysmocom.de>
Gerrit-CC: Pau Espin Pedrol <pespin at sysmocom.de>
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