Re: [PATCH 01/17] Add ida and idr helper routines.

[Tejun Heo <tj@kernel.org>]

Hello,

On Tue, Sep 15, 2015 at 09:46:01AM -0700, Lee Duncan wrote:
> +/**
> + * ida_get_index - allocate a ida index value
> + * @ida		idr handle
> + * @lock	spinlock handle protecting this index
> + * @p_id	pointer to allocated index value
> + *
> + * A helper function for safely allocating an index value (id),
> + * returning a negative errno value on failure, else 0.
> + */
> +static inline int ida_get_index(struct ida *ida, spinlock_t *lock, int *p_id)
> +{
> +	int error = -ENOMEM;
> +
> +	do {
> +		if (!ida_pre_get(ida, GFP_KERNEL))
> +			break;
> +		spin_lock(lock);
> +		error = ida_get_new(ida, p_id);
> +		spin_unlock(lock);
> +	} while (error == -EAGAIN);
> +
> +	return error;
> +}

Obviously ida allocation doesn't need to be synchronized against
anything else.  Why not just use ida_simple_get/remove()?

Thanks.

-- 
tejun