Change in osmo-sgsn[master]: sgsn: Don't attempt to delete GTP pdp ctx if GGSN was restarted

[Pau Espin Pedrol]

Pau Espin Pedrol has uploaded this change for review. ( 
https://gerrit.osmocom.org/9993


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

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
---
M src/gprs/gprs_gmm.c
M src/gprs/gprs_sgsn.c
2 files changed, 17 insertions(+), 6 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-sgsn refs/changes/93/9993/1

diff --git a/src/gprs/gprs_gmm.c b/src/gprs/gprs_gmm.c
index d06fa6c..166c0ad 100644
--- a/src/gprs/gprs_gmm.c
+++ b/src/gprs/gprs_gmm.c
@@ -2699,7 +2699,11 @@
        }
        /* stop timer 3395 */
        pdpctx_timer_stop(pdp, 3395);
-       return sgsn_delete_pdp_ctx(pdp);
+       if (pdp->ggsn)
+               return sgsn_delete_pdp_ctx(pdp);
+       /* GTP side already detached, freeing */
+       sgsn_pdp_ctx_free(pdp);
+       return 0;
 }

 static int gsm48_rx_gsm_status(struct sgsn_mm_ctx *ctx, struct msgb *msg)
diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c
index 35479fb..ef0cc23 100644
--- a/src/gprs/gprs_sgsn.c
+++ b/src/gprs/gprs_sgsn.c
@@ -444,7 +444,8 @@

        /* Detach from MM context */
        pdp_ctx_detach_mm_ctx(pdp);
-       sgsn_delete_pdp_ctx(pdp);
+       if (pdp->ggsn)
+               sgsn_delete_pdp_ctx(pdp);
 }

 /*
@@ -479,8 +480,6 @@
                lib->priv = NULL;
        }

-       if (pdp->destroy_ggsn)
-               sgsn_ggsn_ctx_free(pdp->ggsn);
        talloc_free(pdp);
 }

@@ -702,9 +701,10 @@

 static void drop_one_pdp(struct sgsn_pdp_ctx *pdp)
 {
-       if (pdp->mm->gmm_state == GMM_REGISTERED_NORMAL)
+       if (pdp->mm->gmm_state == GMM_REGISTERED_NORMAL) {
                gsm48_tx_gsm_deact_pdp_req(pdp, GSM_CAUSE_NET_FAIL, true);
-       else  {
+               sgsn_ggsn_ctx_remove_pdp(pdp->ggsn, pdp);
+       } else  {
                /* FIXME: GPRS paging in case MS is SUSPENDED */
                LOGPDPCTXP(LOGL_NOTICE, pdp, "Hard-dropping PDP ctx due to GGSN 
"
                        "recovery\n");
@@ -739,6 +739,13 @@
        llist_del(&pdp->ggsn_list);
        if (llist_empty(&ggc->pdp_list) && osmo_timer_pending(&ggc->echo_timer))
                osmo_timer_del(&ggc->echo_timer);
+       if (pdp->destroy_ggsn)
+               sgsn_ggsn_ctx_free(pdp->ggsn);
+       pdp->ggsn = NULL;
+       /* Drop references to libgtp since the conn is down */
+       if (pdp->lib)
+               pdp_freepdp(pdp->lib);
+       pdp->lib = NULL;
 }

 void sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx)

--
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Gerrit-Project: osmo-sgsn
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I1c74098e181552c218e152bf4ac5035cea770428
Gerrit-Change-Number: 9993
Gerrit-PatchSet: 1
Gerrit-Owner: Pau Espin Pedrol <pes...@sysmocom.de>