From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH v2 2/2] dpaa_eth: add ethtool coalesce control
Date: Fri, 16 Nov 2018 19:42:19 -0800 (PST)
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From: Madalin Bucur <madalin.bucur@nxp.com>
Date: Tue, 13 Nov 2018 18:29:51 +0200

> +	for_each_cpu(cpu, cpus) {
> +		portal = qman_get_affine_portal(cpu);
> +		res = qman_portal_set_iperiod(portal, period);
> +		if (res)
> +			return res;
> +		res = qman_dqrr_set_ithresh(portal, thresh);
> +		if (res)
> +			return res;

Nope, you can't do it like this.

If any intermediate change fails, you have to unwind all of the
changes made up until that point.

Which means you'll have to store the previous setting somewhere
and reinstall those saved values in the error path.