Re: [RFC PATCH net-next 1/5] selftests: forwarding: Introduce deferred commands

[Ido Schimmel <idosch@nvidia.com>]

On Thu, Aug 22, 2024 at 03:49:40PM +0200, Petr Machata wrote:
> In commit 8510801a9dbd ("selftests: drv-net: add ability to schedule
> cleanup with defer()"), a defer helper was added to Python selftests.
> The idea is to keep cleanup commands close to their dirtying counterparts,
> thereby making it more transparent what is cleaning up what, making it
> harder to miss a cleanup, and make the whole cleanup business exception
> safe. All these benefits are applicable to bash as well, exception safety
> can be interpreted in terms of safety vs. a SIGINT.
> 
> This patch therefore introduces a framework of several helpers that serve
> to schedule cleanups in bash selftests:
> 
> - defer_scope_push(), defer_scope_pop(): Deferred statements can be batched
>   together in scopes. When a scope is popped, the deferred commands
>   schoduled in that scope are executed in the order opposite to order of

s/schoduled/scheduled/

>   their scheduling.
> 
> - defer(): Schedules a defer to the most recently pushed scope (or the
>   default scope if none was pushed.)
> 
> - defer_scopes_cleanup(): Pops any unpopped scopes, including the default
>   one. The selftests that use defer should run this in their cleanup
>   function. This is important to get cleanups of interrupted scripts.
> 
>   Consistent use of defers however obviates the need for a separate cleanup
>   function -- everything is just taken care of in defers. So this patch
>   actually introduces a cleanup() helper in the forwarding lib.sh, which
>   calls just pre_cleanup() and defer_scopes_cleanup(). Selftests are
>   obviously still free to override the function.
> 
> - defer_scoped_fn(): Sometimes a function would like to introduce a new
>   defer scope, then run whatever it is that it wants to run, and then pop
>   the scope to run the deferred cleanups. The helper defer_scoped_fn() can
>   be used to derive from one function its wrapper that pushes a defer scope
>   before the function is called, and pops it after it returns.
> 
> The following patches will convert several selftests to this new framework.

The intention is to make sure new tests are using these helpers?

> 
> Signed-off-by: Petr Machata <petrm@nvidia.com>
> ---
>  tools/testing/selftests/net/forwarding/lib.sh | 83 +++++++++++++++++++

Does it make sense to place these helpers in net/lib.sh?