tree d66e1207d8b180116753428a164c1edf490d6fe5
parent 89895b027d57d2352afb56bdfef72c3e106168d6
author Pau Espin Pedrol <pespin@sysmocom.de> 1531492642 +0200
committer Pau Espin Pedrol <pespin@sysmocom.de> 1531747026 +0200

sgsn: Don't attempt to delete GTP pdp ctx if GGSN was restarted

Scenario and behaviour before this commit:
- Received Echo Reply from GGSN has incremented RestartCounter
- func sgsn_ggsn_ctx_drop_all_pdp() is called to dettach all pdp ctx
from GGSN and request the MS to deact all related ctx.
- DEACT ACCEPT is received from MS, and then it tries to send DEL PDP CTX
to GGSN, expecting to receive a Confirmation and only then freeing the
pdp ctx.

The problem is that since the initial cause of triggering was a GGSN
restart, the GGSN doesn't know anything about that pdp ctx anymore, so
it's not useful sending it. We can instead dettach the GGSN and libgtp
ref at drop_all_pdp() time and then when we receive DEACT ACCEPT from MS
we can free the pdp ctx directly.

Change-Id: I1c74098e181552c218e152bf4ac5035cea770428