tbf: Store the timing advance (TA) value in the GprsMs object

The TA value rather relates to an MS and not to a single TBF. So all
TBFs share the same TA value. Currently the TA value is stored per
TBF and eventually copied from an old TBF to a new one. It is in
general only passed with an RACH request when the TLLI and thus the
MS is not yet known.

This commit adds a TA member to the GprsMs class and uses that one
when the TBF is associated to an MS object. Since the TBF is not
always associated with an MS object (after RACH or when it has been
replaced by another TBF), the TA value is still stored in each TBF
and that value is used as long as no MS object is being associated.

Sponsored-by: On-Waves ehf

1 files changed, 26 insertions, 6 deletions

diff --git a/src/tbf.cpp b/src/tbf.cpp
index ac0cdf3f..53f1ae13 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -89,13 +89,32 @@ void gprs_rlcmac_tbf::assign_imsi(const char *imsi_)
 	m_ms->set_imsi(imsi_);
 }
 
+uint8_t gprs_rlcmac_tbf::ta() const
+{
+	return m_ms ? m_ms->ta() : m_ta;
+}
+
+void gprs_rlcmac_tbf::set_ta(uint8_t ta)
+{
+	if (ms())
+		ms()->set_ta(ta);
+
+	m_ta = ta;
+}
+
 void gprs_rlcmac_tbf::set_ms(GprsMs *ms)
 {
 	if (m_ms == ms)
 		return;
 
-	if (m_ms)
+	if (m_ms) {
+		/* Save the TA locally. This will also be called, if the MS
+		 * object detaches itself from the TBF, for instance if
+		 * attach_tbf() is called */
+		m_ta = m_ms->ta();
+
 		m_ms->detach_tbf(this);
+	}
 
 	m_ms = ms;
 
@@ -110,6 +129,9 @@ void gprs_rlcmac_tbf::update_ms(uint32_t tlli, enum gprs_rlcmac_tbf_direction di
 		if (!new_ms)
 			new_ms = bts->ms_store().create_ms(tlli, dir);
 
+		if (dir == GPRS_RLCMAC_UL_TBF)
+			new_ms->set_ta(m_ta);
+
 		set_ms(new_ms);
 		return;
 	}
@@ -144,11 +166,13 @@ gprs_rlcmac_ul_tbf *tbf_alloc_ul(struct gprs_rlcmac_bts *bts,
 		return NULL;
 	}
 	tbf->m_contention_resolution_done = 1;
-	tbf->ta = ta; /* use current TA */
 	tbf->set_state(GPRS_RLCMAC_ASSIGN);
 	tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_PACCH);
 	tbf_timer_start(tbf, 3169, bts->t3169, 0);
 	tbf->update_ms(tlli, GPRS_RLCMAC_UL_TBF);
+	OSMO_ASSERT(tbf->ms());
+
+	tbf->ms()->set_ta(ta);
 
 	return tbf;
 }
@@ -786,8 +810,6 @@ void gprs_rlcmac_tbf::free_all(struct gprs_rlcmac_pdch *pdch)
 
 void gprs_rlcmac_tbf::update_tlli(uint32_t tlli)
 {
-	/* update the timing advance for the new tlli */
-	bts->timing_advance()->update(0, tlli, ta);
 }
 
 int gprs_rlcmac_tbf::extract_tlli(const uint8_t *data, const size_t len)
@@ -843,8 +865,6 @@ int gprs_rlcmac_tbf::extract_tlli(const uint8_t *data, const size_t len)
 		tbf_free(ul_tbf);
 		ul_tbf = NULL;
 	}
-	/* store current timing advance */
-	bts->timing_advance()->remember(tlli(), ta);
 	return 1;
 }