Dangling pointer warnings building NRF Connect SDK with ARM GCC 13.2

RE: Dangling pointer warnings building NRF Connect SDK with ARM GCC 13.2

Håkon Alseth — Fri, 02 Feb 2024 08:15:42 GMT

Hi!

[quote user="dpalchak-google"]Yeah, just warning needed to be suppressed. Thanks![/quote]

Again; I should be thanking you for making us aware of the issue. It is highly appreciated!

The PR is now merged, and future versions of NCS will have the warning ignored for the code snippet in question.

I hope you have a wonderful weekend when that time comes!

Kind regards,

Håkon

RE: Dangling pointer warnings building NRF Connect SDK with ARM GCC 13.2

David Palchak — Thu, 01 Feb 2024 17:44:03 GMT

Yeah, just warning needed to be suppressed. Thanks!

RE: Dangling pointer warnings building NRF Connect SDK with ARM GCC 13.2

Håkon Alseth — Thu, 01 Feb 2024 08:58:24 GMT

Hi again,

Replying to myself here.

It does indeed look suspicions at first glance (I also believed so), but after discussing this with the developer who wrote the code initially, it is always removed from the list within the same scope.

The code (taken from here https://github.com/nrfconnect/sdk-nrf/blob/v2.5.1/lib/nrf_modem_lib/nrf_modem_os.c#L177-L183) is:

    struct sleeping_thread thread;
    
    ...
    
	if (!sleeping_thread_add(&thread)) {
		return 0;
	}

	(void)k_sem_take(&thread.sem, SYS_TIMEOUT_MS(*timeout));

	sleeping_thread_remove(&thread);

Each thread (or socket actually in the scope of nRF91-series) that enters here will allocate a dedicated sleeping_thread var, which will await until it is awoken again before removing it from the slist entry.

Making "thread" static would break the reentrancy of the function itself, allowing for only one network socket to be sleeping at the time.

We will look into pushing a pragma to disable the -Wdangling-pointer warning for this specific scope, with a proper comment explaining why.

*edit* Here's the proposed PR: https://github.com/nrfconnect/sdk-nrf/pull/13830

Kind regards,

Håkon

RE: Dangling pointer warnings building NRF Connect SDK with ARM GCC 13.2

Håkon Alseth — Thu, 01 Feb 2024 08:04:43 GMT

Hi,

Thank you for reporting this back to us, and helping up improve upon our delivery!

I'll will report this back to our nRF91 team.

Kind regards,

Håkon