- most were trivial
- missing group close or open
- extra space
- no doxygen comment
- name commad might open an implicit group
this hould also be implicit cosed but does not happen somtimes
- crazy: internal declared groups have to be closed internal
The new `gnrc_tx_sync` module allows users of the GNRC network stack to
synchronize with the actual transmission of outgoing packets. This is directly
integrated into gnrc_sock. Hence, if `gnrc_tx_sync` is used, calls to e.g.
sock_udp_send() will block until the network stack has processed the message.
Use cases:
1. Prevent packet drop when sending at high rate
- If the application is sending faster than the stack can handle, the
message queues will overflow and outgoing packets are lost
2. Passing auxiliary data about the transmission back the stack
- When e.g. the number of required retransmissions, the transmission time
stamp, etc. should be made available to a user of an UDP sock, a
synchronization mechanism is needed
3. Simpler error reporting without footguns
- The current approach of using `core/msg` for passing up error messages is
difficult to use if other message come in. Currently, gnrc_sock is
busy-waiting and fetching messages from the message queue until the number
of expected status reports is received. It will enqueue all
non-status-report messages again at the end of the queue. This has
multiple issues:
- Busy waiting is especially in lower power scenarios with time slotted
MAC protocols harmful, as the CPU will remain active and consume
power even though the it could sleep until the TX slot is reached
- The status reports from the network stack are send to the user thread
blocking. If the message queue of the user thread is full, the network
stack would block until the user stack can fetch the messages. If
another higher priority thread would start sending a message, it
would busy wait for its status reports to completely come in. Hence,
the first thread doesn't get CPU time to fetch messages and unblock
the network stack. As a result, the system would lock up completely.
- Just adding the error/status code to the gnrc_tx_sync_t would preallocate
and reserve memory for the error reporting. That way gnrc_sock does not
need to search through the message queue for status reports and the
network stack does not need to block for the user thread fetching it.
The logic used to check whether the RX timestamp was provided in the GNRC
implementation of `sock_ip_recv_buf_aux()` is incorrect: It still uses in-band
signalling via a timestamp of zero, but a dedicated flag was added to allow for
timestamps of zero.
Additionally, it is not necessary to check if a bit is set only to clear it -
clearing it unconditionally is faster and smaller.
Replace direct accesses to sched_active_thread and sched_active_pid with
the helper functions thread_getpid() and thread_get_active(). This serves
two purposes:
1. It makes accidental writes to those variable from outside core less likely.
2. Casting off the volatile qualifier is now well contained to those two
functions
This changes the configuration macro to be the exponent of 2^n, as the
mbox buffer size needs to be always power of 2. The macro now has the
GNRC prefix.
Also a compile configuration documentation group is created.
The termination condition implemented in gnrc_pktbuf_malloc does not
work when using the sock interface as sock copies packet data to a local
buffer and frees the packet afterwards. As such, the fuzzing application
would exit before performing any input processing.
For this reason, the termination condition in gnrc_pktbuf_malloc is
disabled when using sock. Instead, the application terminates if
gnrc_sock_recv previously returned the fuzzing packet. The underlying
assumption of this implementation is that gnrc_sock_recv is called in a
loop.
