Re: [PATCH 1/2] percpu_ref: percpu_ref_tryget_live() version holding RCU

[Tejun Heo]

On Wed, Oct 20, 2021 at 09:03:18PM +0100, Pavel Begunkov wrote:
> +/**
> + * percpu_ref_tryget_live_rcu - same as percpu_ref_tryget_live() but the
> + * caller is responsible for taking RCU.
> + *
> + * This function is safe to call as long as @ref is between init and exit.
> + */
> +static inline bool percpu_ref_tryget_live_rcu(struct percpu_ref *ref)
> +{
> +	unsigned long __percpu *percpu_count;
> +	bool ret = false;
> +
> +	if (likely(__ref_is_percpu(ref, &percpu_count))) {
> +		this_cpu_inc(*percpu_count);
> +		ret = true;
> +	} else if (!(ref->percpu_count_ptr & __PERCPU_REF_DEAD)) {
> +		ret = atomic_long_inc_not_zero(&ref->data->count);
> +	}
> +	return ret;
> +}

Can we please add rcu_read_lock_held() assertion? Other than that, looks
fine to me.

Thanks.

-- 
tejun