[PATCH v4 6/6] devtools: forbid new direct use of GCC atomic builtins

[Morten Brørup]

> From: Tyler Retzlaff [mailto:roretzla at linux.microsoft.com]
> Sent: Wednesday, 16 August 2023 23.39
> 
> Refrain from using compiler __atomic_xxx builtins DPDK now requires
> the use of rte_atomic_<op>_explicit macros when operating on DPDK
> atomic variables.

There is probably no end to how much can be added to checkpatches.

You got the important stuff, so below are only further suggestions!

[...]

> -	# refrain from using compiler __atomic_{add,and,nand,or,sub,xor}_fetch()
> +	# refrain from using compiler __atomic_xxx builtins
>  	awk -v FOLDERS="lib drivers app examples" \
> -		-v EXPRESSIONS="__atomic_(add|and|nand|or|sub|xor)_fetch\\\(" \
> +		-v EXPRESSIONS="__atomic_.*\\\(" \
>  		-v RET_ON_FAIL=1 \
> -		-v MESSAGE='Using __atomic_op_fetch, prefer __atomic_fetch_op' \
> +		-v MESSAGE='Using __atomic_xxx builtins' \

Alternatively:
		-v MESSAGE='Using __atomic_xxx built-ins, prefer rte_atomic_xxx' \

>  		-f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
>  		"$1" || res=1
> 
> --
> 1.8.3.1

This could be updated too:

	# refrain from using compiler __atomic_thread_fence()
	# It should be avoided on x86 for SMP case.
	awk -v FOLDERS="lib drivers app examples" \
		-v EXPRESSIONS="__atomic_thread_fence\\\(" \
		-v RET_ON_FAIL=1 \
-		-v MESSAGE='Using __atomic_thread_fence' \
+		-v MESSAGE='Using __atomic_thread_fence built-in, prefer __rte_atomic_thread_fence' \
		-f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
		"$1" || res=1

You could also add C11 variants of these tests...
atomic_(load|store|exchange|compare_exchange_(strong|weak)|fetch_(add|sub|and|xor|or|nand)|flag_(test_and_set|clear))[_explicit], and
atomic_thread_fence.

And a test for using "_Atomic".

-Morten