Maintain per ggsn pdp ctx list

This way we can easily track all pdp context associated to a specific
ggsn, which is useful to handle some scenarios, such as the one
implemented in next commit, in which specs references that GSNs should
ping only other GSNs with at least one pdp ctx in common. So the list
of pdp ctx per GGSN is really useful too (and cheap computationally)
to check if we should arm or disarm the echo procedure timer.

So this commit can be seen as a preparation for next commit.

Change-Id: I3bbcc0883df2bf1290ba8d4bd70db8baa494087a

3 files changed, 18 insertions, 17 deletions

diff --git a/include/osmocom/sgsn/gprs_sgsn.h b/include/osmocom/sgsn/gprs_sgsn.h
index 64e5619d6..33b12dc25 100644
--- a/include/osmocom/sgsn/gprs_sgsn.h
+++ b/include/osmocom/sgsn/gprs_sgsn.h
@@ -296,6 +296,7 @@ struct sgsn_pdp_ctx {
 	struct sgsn_mm_ctx	*mm;	/* back pointer to MM CTX */
 	int			destroy_ggsn; /* destroy it on destruction */
 	struct sgsn_ggsn_ctx	*ggsn;	/* which GGSN serves this PDP */
+	struct llist_head	ggsn_list;	/* list_head for ggsn->pdp_list */
 	struct rate_ctr_group	*ctrg;
 
 	//unsigned int		id;
@@ -338,6 +339,7 @@ struct sgsn_pdp_ctx *sgsn_pdp_ctx_by_tid(const struct sgsn_mm_ctx *mm,
 					 uint8_t tid);
 
 struct sgsn_pdp_ctx *sgsn_pdp_ctx_alloc(struct sgsn_mm_ctx *mm,
+					struct sgsn_ggsn_ctx *ggsn,
 					uint8_t nsapi);
 void sgsn_pdp_ctx_terminate(struct sgsn_pdp_ctx *pdp);
 void sgsn_pdp_ctx_free(struct sgsn_pdp_ctx *pdp);
@@ -350,12 +352,14 @@ struct sgsn_ggsn_ctx {
 	struct in_addr remote_addr;
 	int remote_restart_ctr;
 	struct gsn_t *gsn;
+	struct llist_head pdp_list;	/* list of associated pdp ctx (struct sgsn_pdp_ctx*) */
 };
 struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_alloc(uint32_t id);
 void sgsn_ggsn_ctx_free(struct sgsn_ggsn_ctx *ggc);
 struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_by_id(uint32_t id);
 struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_by_addr(struct in_addr *addr);
 struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_find_alloc(uint32_t id);
+int sgsn_ggsn_ctx_drop_all_pdp(struct sgsn_ggsn_ctx *ggsn);
 
 struct apn_ctx {
 	struct llist_head list;
@@ -378,10 +382,6 @@ extern struct llist_head sgsn_pdp_ctxts;
 uint32_t sgsn_alloc_ptmsi(void);
 void sgsn_inst_init(void);
 
-/* High-level function to be called in case a GGSN has disappeared or
- * ottherwise lost state (recovery procedure) */
-int drop_all_pdp_for_ggsn(struct sgsn_ggsn_ctx *ggsn);
-
 char *gprs_pdpaddr2str(uint8_t *pdpa, uint8_t len);
 
 /*
diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c
index 688eaed18..a58e504c5 100644
--- a/src/gprs/gprs_sgsn.c
+++ b/src/gprs/gprs_sgsn.c
@@ -388,6 +388,7 @@ struct sgsn_pdp_ctx *sgsn_pdp_ctx_by_tid(const struct sgsn_mm_ctx *mm,
 
 /* you don't want to use this directly, call sgsn_create_pdp_ctx() */
 struct sgsn_pdp_ctx *sgsn_pdp_ctx_alloc(struct sgsn_mm_ctx *mm,
+					struct sgsn_ggsn_ctx *ggsn,
 					uint8_t nsapi)
 {
 	struct sgsn_pdp_ctx *pdp;
@@ -401,6 +402,7 @@ struct sgsn_pdp_ctx *sgsn_pdp_ctx_alloc(struct sgsn_mm_ctx *mm,
 		return NULL;
 
 	pdp->mm = mm;
+	pdp->ggsn = ggsn;
 	pdp->nsapi = nsapi;
 	pdp->ctrg = rate_ctr_group_alloc(pdp, &pdpctx_ctrg_desc, nsapi);
 	if (!pdp->ctrg) {
@@ -409,6 +411,7 @@ struct sgsn_pdp_ctx *sgsn_pdp_ctx_alloc(struct sgsn_mm_ctx *mm,
 		return NULL;
 	}
 	llist_add(&pdp->list, &mm->pdp_list);
+	llist_add(&pdp->ggsn_list, &ggsn->pdp_list);
 	llist_add(&pdp->g_list, &sgsn_pdp_ctxts);
 
 	return pdp;
@@ -462,6 +465,8 @@ void sgsn_pdp_ctx_free(struct sgsn_pdp_ctx *pdp)
 	rate_ctr_group_free(pdp->ctrg);
 	if (pdp->mm)
 		llist_del(&pdp->list);
+	if (pdp->ggsn)
+		llist_del(&pdp->ggsn_list);
 	llist_del(&pdp->g_list);
 
 	/* _if_ we still have a library handle, at least set it to NULL
@@ -496,6 +501,7 @@ struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_alloc(uint32_t id)
 	ggc->remote_restart_ctr = -1;
 	/* if we are called from config file parse, this gsn doesn't exist yet */
 	ggc->gsn = sgsn->gsn;
+	INIT_LLIST_HEAD(&ggc->pdp_list);
 	llist_add(&ggc->list, &sgsn_ggsn_ctxts);
 
 	return ggc;
@@ -503,6 +509,7 @@ struct sgsn_ggsn_ctx *sgsn_ggsn_ctx_alloc(uint32_t id)
 
 void sgsn_ggsn_ctx_free(struct sgsn_ggsn_ctx *ggc)
 {
+	OSMO_ASSERT(llist_empty(&ggc->pdp_list));
 	llist_del(&ggc->list);
 	talloc_free(ggc);
 }
@@ -702,19 +709,14 @@ static void drop_one_pdp(struct sgsn_pdp_ctx *pdp)
 
 /* High-level function to be called in case a GGSN has disappeared or
  * otherwise lost state (recovery procedure) */
-int drop_all_pdp_for_ggsn(struct sgsn_ggsn_ctx *ggsn)
+int sgsn_ggsn_ctx_drop_all_pdp(struct sgsn_ggsn_ctx *ggsn)
 {
-	struct sgsn_mm_ctx *mm;
 	int num = 0;
 
-	llist_for_each_entry(mm, &sgsn_mm_ctxts, list) {
-		struct sgsn_pdp_ctx *pdp;
-		llist_for_each_entry(pdp, &mm->pdp_list, list) {
-			if (pdp->ggsn == ggsn) {
-				drop_one_pdp(pdp);
-				num++;
-			}
-		}
+	struct sgsn_pdp_ctx *pdp, *pdp2;
+	llist_for_each_entry_safe(pdp, pdp2, &ggsn->pdp_list, ggsn_list) {
+		drop_one_pdp(pdp);
+		num++;
 	}
 
 	return num;
diff --git a/src/gprs/sgsn_libgtp.c b/src/gprs/sgsn_libgtp.c
index 70112cbfd..2da8c4a74 100644
--- a/src/gprs/sgsn_libgtp.c
+++ b/src/gprs/sgsn_libgtp.c
@@ -145,7 +145,7 @@ struct sgsn_pdp_ctx *sgsn_create_pdp_ctx(struct sgsn_ggsn_ctx *ggsn,
 	const uint8_t *qos;
 	int rc;
 
-	pctx = sgsn_pdp_ctx_alloc(mmctx, nsapi);
+	pctx = sgsn_pdp_ctx_alloc(mmctx, ggsn, nsapi);
 	if (!pctx) {
 		LOGP(DGPRS, LOGL_ERROR, "Couldn't allocate PDP Ctx\n");
 		return NULL;
@@ -160,7 +160,6 @@ struct sgsn_pdp_ctx *sgsn_create_pdp_ctx(struct sgsn_ggsn_ctx *ggsn,
 	}
 	pdp->priv = pctx;
 	pctx->lib = pdp;
-	pctx->ggsn = ggsn;
 
 	//pdp->peer =	/* sockaddr_in of GGSN (receive) */
 	//pdp->ipif =	/* not used by library */
@@ -603,7 +602,7 @@ static int cb_recovery(struct sockaddr_in *peer, uint8_t recovery)
 		     "releasing all PDP contexts\n",
 		     ggsn->remote_restart_ctr, recovery);
 		ggsn->remote_restart_ctr = recovery;
-		drop_all_pdp_for_ggsn(ggsn);
+		sgsn_ggsn_ctx_drop_all_pdp(ggsn);
 	}
 	return 0;
 }