zephyr/subsys/ipc
Rafał Kuźnia 5b12b6ab55 ipc: icmsg: Dedicated workqueue for ICMSG backend
The ICMSG backend now has a dedicated workqueue to process incoming IPC
messages. The system workqueue is no longer utilized for that purpose.

Testing shows that in certain scenarios substituting a RPMsg backend
with ICMsg results in deadlocks.
The deadlocks were a symptom of running a synchronous RPC protocol from
the context of the system workqueue and transpired as follows:

1. The RPC protocol sends a request over the ICMsg backend on the system
   workqueue thread.
2. The RPC protocol puts the thread to sleep until response is received.
   This puts the system workqueue thread to sleep.
3. The response to the request arrives over ICMsg backend.
4. The backend signals a work item to the system workqueue.
5. The system workqueue is unable to process the response due to being
   previously pended on the RPC request.

The deadlock was initially observed with the nrf-802154 driver in
conjuntion with the IPv6 stack.

To prevent this condition from occurring, the approach was selected to
give ICMsg a dedicated workqueue thread.

Added a Kconfig option that enables the dedicated workqueue by default.
The config can be disabled, if the user wants to preserve RAM capacity
and is certain that the deadlock condition is not encountered.

Signed-off-by: Rafał Kuźnia <rafal.kuznia@nordicsemi.no>
2023-09-12 10:17:27 +02:00
..
ipc_service ipc: icmsg: Dedicated workqueue for ICMSG backend 2023-09-12 10:17:27 +02:00
rpmsg_service ipc: rpmsg_service: s/device.h/init.h 2023-09-05 12:01:01 +02:00
CMakeLists.txt
Kconfig