netdev - Re: [PATCH net-next 1/3] cxgb4: add mirror action to TC-MATCHALL offload

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Message-ID: <20200626211844.40ed466c@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 26 Jun 2020 21:18:44 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Rahul Lakkireddy <rahul.lakkireddy@...lsio.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, nirranjan@...lsio.com,
        vishal@...lsio.com, dt@...lsio.com
Subject: Re: [PATCH net-next 1/3] cxgb4: add mirror action to TC-MATCHALL
 offload

On Thu, 25 Jun 2020 17:28:41 +0530 Rahul Lakkireddy wrote:
> +	if (refcount_read(&pi->vi_mirror_refcnt) > 1) {
> +		refcount_dec(&pi->vi_mirror_refcnt);
> +		return;
> +	}

FWIW this looks very dodgy. If you know nothing changes the count
between the read and the dec here, you probably don't need atomic
refcounts at all..