llc_queue::{dequeue,enqueue}() refactor

As seen in OS#4420, setting the MetaInfo.recv_time outside of
llc_queue before calling llc_queue::enqueue() and later on using that
value in llc_queue itself at dequeue time is not a good idea, since it
can provoke errors if the recv_time was not set correctly.
For instance, LlcTest was not setting the value for recv_time on some
test, which ended up with a huge millisec value when substracting now()
from it:
"""
llc.cpp:215:29: runtime error: signed integer overflow: 1582738663 * 1000 cannot be represented in type 'long int'
"""
This issue only appeared when started building on a raspberrypi4.

Let's better set/store the MetaInfo.recv_time internally during
llc_queue::enqueue(). Then, enqueue() only needs the
MetaInfo.expire_time, so let's change its arg list to only receive that
to avoid confusions.

Take the chance to move the llc_queue APIs to use osmo_gettimeofday,
since we need to fake the time now that the API itself sets that time.

Also take the chance during this refactor to disallow passing null
pointer by default since no user needs that.

Finally, update the LlcTest accordingly with all API/behavior changes.

Related: OS#4420
Change-Id: Ief6b1464dc779ff22adc2b02da7a006cd772ebce

3 files changed, 13 insertions, 11 deletions

diff --git a/src/llc.cpp b/src/llc.cpp
index b1550635..4cd0cc45 100644
--- a/src/llc.cpp
+++ b/src/llc.cpp
@@ -103,18 +103,19 @@ void gprs_llc_queue::init()
 	m_avg_queue_delay = 0;
 }
 
-void gprs_llc_queue::enqueue(struct msgb *llc_msg, const MetaInfo *info)
+
+void gprs_llc_queue::enqueue(struct msgb *llc_msg, const struct timeval *expire_time)
 {
-	static const MetaInfo def_meta = {{0}};
 	MetaInfo *meta_storage;
 
-	osmo_static_assert(sizeof(*info) <= sizeof(llc_msg->cb), info_does_not_fit);
+	osmo_static_assert(sizeof(*meta_storage) <= sizeof(llc_msg->cb), info_does_not_fit);
 
 	m_queue_size += 1;
 	m_queue_octets += msgb_length(llc_msg);
 
 	meta_storage = (MetaInfo *)&llc_msg->cb[0];
-	*meta_storage = info ? *info : def_meta;
+	osmo_gettimeofday(&meta_storage->recv_time, NULL);
+	meta_storage->expire_time = *expire_time;
 
 	msgb_enqueue(&m_queue, llc_msg);
 }
@@ -208,7 +209,7 @@ struct msgb *gprs_llc_queue::dequeue(const MetaInfo **info)
 	m_queue_octets -= msgb_length(msg);
 
 	/* take the second time */
-	gettimeofday(&tv_now, NULL);
+	osmo_gettimeofday(&tv_now, NULL);
 	tv = (struct timeval *)&msg->data[sizeof(*tv)];
 	timersub(&tv_now, &meta_storage->recv_time, &tv_result);
 
@@ -234,7 +235,7 @@ void gprs_llc_queue::calc_pdu_lifetime(BTS *bts, const uint16_t pdu_delay_csec,
 
 	/* calculate timestamp of timeout */
 	struct timeval now, csec;
-	gettimeofday(&now, NULL);
+	osmo_gettimeofday(&now, NULL);
 	csec.tv_usec = (delay_csec % 100) * 10000;
 	csec.tv_sec = delay_csec / 100;
 
diff --git a/src/llc.h b/src/llc.h
index 2e7229ce..8667e003 100644
--- a/src/llc.h
+++ b/src/llc.h
@@ -75,7 +75,7 @@ struct gprs_llc_queue {
 
 	void init();
 
-	void enqueue(struct msgb *llc_msg, const MetaInfo *info = 0);
+	void enqueue(struct msgb *llc_msg, const struct timeval *expire_time);
 	struct msgb *dequeue(const MetaInfo **info = 0);
 	void clear(BTS *bts);
 	void move_and_merge(gprs_llc_queue *o);
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 7113d65a..5c0fd9d6 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -108,16 +108,17 @@ int gprs_rlcmac_dl_tbf::append_data(const uint8_t ms_class,
 				const uint16_t pdu_delay_csec,
 				const uint8_t *data, const uint16_t len)
 {
+	struct timeval expire_time;
+
 	LOGPTBFDL(this, LOGL_DEBUG, "appending %u bytes\n", len);
-	gprs_llc_queue::MetaInfo info;
+
 	struct msgb *llc_msg = msgb_alloc(len, "llc_pdu_queue");
 	if (!llc_msg)
 		return -ENOMEM;
 
-	gprs_llc_queue::calc_pdu_lifetime(bts, pdu_delay_csec, &info.expire_time);
-	gettimeofday(&info.recv_time, NULL);
+	gprs_llc_queue::calc_pdu_lifetime(bts, pdu_delay_csec, &expire_time);
 	memcpy(msgb_put(llc_msg, len), data, len);
-	llc_queue()->enqueue(llc_msg, &info);
+	llc_queue()->enqueue(llc_msg, &expire_time);
 	tbf_update_ms_class(this, ms_class);
 	start_llc_timer();