Re: [PATCH 20/21] context_tracking: Convert state to atomic_t

nicolas saenz julienne
2022-05-18T15:10:07Z

On Tue, 2022-05-03 at 12:00 +0200, Frederic Weisbecker wrote:

[...]

> +/**
> + * ct_state() - return the current context tracking state if known
> + *
> + * Returns the current cpu's context tracking state if context tracking
> + * is enabled. If context tracking is disabled, returns
> + * CONTEXT_DISABLED. This should be used primarily for debugging.
> + */
> +static __always_inline int ct_state(void)
> +{
> + int ret;
> +
> + if (!context_tracking_enabled())
> + return CONTEXT_DISABLED;
> +
> + preempt_disable();
> + ret = __ct_state();
> + preempt_enable();
> +
> + return ret;
> +}
> +

I can't see any use for this function with preemption enabled. You can't trust
the data due to CPU migration and it could be a source of bugs in the future.
Wouldn't it make more sense to move the burden into the callers? They all DTRT,
plus, this_cpu_ptr() will spew warnings if someone shows up and doesn't comply.

Regards,

--
Nicolás Sáenz