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
This lock was removed in 1cbf7eac because it was considered unneeded.
However, as can be seen in issue #1503, we need to protect the access
to rx_window, for example.
Issue #1503 shows a stack trace where a PHY worker generates a status PDU.
While holding the mutex to access rx_window, the stack thread on the
other hand, happily accesses the rx_window member without acquiring
the lock. This commit protects all handle_*() functions in write_pdu().
This reverts commit 1cbf7eac04.
* Clang-formated UE, eNB and lib.
* Fixed compiling errors from clang-format.
* Fix linking issues introduced by clang-format
* Fix poor formating in initializing arrays of arrays.
* Fix mistake in conflict resolution on rm_turbo.c
* Re-apply clang format to gtpc_ies.h