Change in ...osmo-sgsn[master]: gprs_sgsn.c: Remove recently introduced assert

pespin gerrit-no-reply at lists.osmocom.org
Tue Aug 13 18:23:16 UTC 2019


pespin has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-sgsn/+/15188


Change subject: gprs_sgsn.c: Remove recently introduced assert
......................................................................

gprs_sgsn.c: Remove recently introduced assert

Recent commit added an assert to make sure unexpected conditions were
happening in sgsn_mm_ctx_cleanup_free(). Old code was passing
mm->gb.tlli to gprs_llgmm_assign with "new tlli" being all-1's (aka
unassign mm->gb.tlli).
The commit changed the code to use gprs_llgmm_unassign, which uses
llme->tlli instead of mm->gb.tlli, and the assert was used to make sure
no behavior change occured with the commit.
It seems TTCN3 test TC_attach_auth_id_timeout triggers that assert, and
after closer debug it seems mm->gb.tlli == llme->old_tlli, which makes
sense since there's a mm->gb.tlli_new which is expected to be
llme->tlli.
When TLLI changes in GMM, it is stored into mm->gb.tlli_new and assigned
on the LLC layer using gprs_llgm_assign(), and at the end of the function
(after handling messages) it is assigned to mm->gb.tlli (and value kept
in mm->gb.tlli_new).
So mm->gb.tlli and mm->gb.tlli_new usually contain the same value unless
a new TLLI is allocated, and during the span of the Rx path it is kept
different, the LLC layer having assigned the value of mm->gb.tlli_new.
So,  old code (before the commit adding the assert) was wrongly using
mm->gb.tlli instead of mm->gb.tlli_new at the moment of unassigning (but
not really problematic in practice since behavior is the same as long as
"old TLLI" value is not all-1's.
So we are fine and correct using gprs_llgm_unassign() (which passes llme->tlli
as "old TLLI") instead of what used to be done before.
In any case, the expected behavior is to free the llme object and get
rid of everything...

Fixes: 788863cda53298c24110d0fe0f8cd3309cdec747
Change-Id: I482acdbdf05ce0cb0a5804206672512854067f5b
---
M src/gprs/gprs_sgsn.c
1 file changed, 0 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-sgsn refs/changes/88/15188/1

diff --git a/src/gprs/gprs_sgsn.c b/src/gprs/gprs_sgsn.c
index 8f1e54a..eb04846 100644
--- a/src/gprs/gprs_sgsn.c
+++ b/src/gprs/gprs_sgsn.c
@@ -313,7 +313,6 @@
 void sgsn_mm_ctx_cleanup_free(struct sgsn_mm_ctx *mm)
 {
 	struct gprs_llc_llme *llme = NULL;
-	uint32_t tlli = mm->gb.tlli;
 	struct sgsn_pdp_ctx *pdp, *pdp2;
 	struct sgsn_signal_data sig_data;
 
@@ -362,7 +361,6 @@
 
 	if (llme) {
 		/* TLLI unassignment, must be called after sgsn_mm_ctx_free */
-		OSMO_ASSERT(llme->tlli == tlli);
 		if (gprs_llgmm_unassign(llme) < 0)
 			LOGMMCTXP(LOGL_ERROR, mm, "gprs_llgmm_unassign failed, llme not freed!\n");
 	}

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Gerrit-Project: osmo-sgsn
Gerrit-Branch: master
Gerrit-Change-Id: I482acdbdf05ce0cb0a5804206672512854067f5b
Gerrit-Change-Number: 15188
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <pespin at sysmocom.de>
Gerrit-MessageType: newchange
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