* add locked and unlocked version of has_data() since one is
called from stack and one from PHY threads
* add comments in each interface section as to why locking
is required or not
* remove RLC rwlock when not required
* move calls only used by RRC to RRC section
this patch refactors the SDU queuing and dropping policy of the RLC and PDCP layer.
the previous design had issues when packets have been generated at a higher
rate above the PDCP than they could be consumed below the RLC.
When the RLC SDU queues were full, we allowed two policies, one to block on the write
and the other to drop the SDU. Both options are not ideal because they either
lead to a blocking stack thread or to lost PDCP PDUs.
To avoid this, this patch makes the following changes:
* PDCP monitors RLC's SDU queue and drops packets on its north-bound SAP if queues are full
* a new method sdu_queue_is_full() has been added to the RLC interface for PDCP
* remove blocking write from pdcp and rlc write_sdu() interface
* all writes into queues need to be non-blocking
* if Tx queues are overflowing, SDUs are dropped above PDCP, not RLC
* log warning if RLC still needs to drop SDUs
* this case should be avoided with the monitoring mechanism
* Added the appropriate code for handling and sending the
re-establishment procedure messages to rrc_ue.c/.h.
* Triggered RRC reconfiguration after the reception of RRC
re-establishment complete
* Refreshed K_eNB at the reception of re-establishment
request
* Changed the mapping of TEIDs to RNTIs in the GTP-U layer,
as the RNTI might change with reestablishment.