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Date: Thu, 18 Apr 2024 16:22:55 +0300 (EEST)
From: Julian Anastasov <ja@ssi.bg>
To: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
cc: horms@verge.net.au, netdev@vger.kernel.org, lvs-devel@vger.kernel.org,
        netfilter-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>
Subject: Re: [PATCH net-next v2 1/2] ipvs: add READ_ONCE barrier for
 ipvs->sysctl_amemthresh
In-Reply-To: <20240418110153.102781-1-aleksandr.mikhalitsyn@canonical.com>
Message-ID: <eb0b4b89-9a1f-0e1b-9744-6eb3396048bd@ssi.bg>
References: <20240418110153.102781-1-aleksandr.mikhalitsyn@canonical.com>
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	Hello,

On Thu, 18 Apr 2024, Alexander Mikhalitsyn wrote:

> Cc: Julian Anastasov <ja@ssi.bg>
> Cc: Simon Horman <horms@verge.net.au>
> Cc: Pablo Neira Ayuso <pablo@netfilter.org>
> Cc: Jozsef Kadlecsik <kadlec@netfilter.org>
> Cc: Florian Westphal <fw@strlen.de>
> Suggested-by: Julian Anastasov <ja@ssi.bg>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> ---
>  net/netfilter/ipvs/ip_vs_ctl.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 143a341bbc0a..daa62b8b2dd1 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c

> @@ -105,7 +106,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
>  	/* si_swapinfo(&i); */
>  	/* availmem = availmem - (i.totalswap - i.freeswap); */
>  
> -	nomem = (availmem < ipvs->sysctl_amemthresh);
> +	amemthresh = max(READ_ONCE(ipvs->sysctl_amemthresh), 0);
> +	nomem = (availmem < amemthresh);
>  
>  	local_bh_disable();
>  
> @@ -146,8 +148,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
>  	case 1:
>  		if (nomem) {
>  			ipvs->drop_rate = ipvs->drop_counter
> -				= ipvs->sysctl_amemthresh /
> -				(ipvs->sysctl_amemthresh-availmem);
> +				= amemthresh /
> +				(amemthresh-availmem);

	Thanks, both patches look ok except that the old styling
is showing warnings for this patch:

scripts/checkpatch.pl --strict /tmp/file1.patch

	It would be great if you silence them somehow in v3...

	BTW, est_cpulist is masked with current->cpus_mask of the
sysctl writer process, if that is of any help. That is why I skipped
it but lets keep it read-only for now...

>  			ipvs->sysctl_drop_packet = 2;
>  		} else {
>  			ipvs->drop_rate = 0;
> @@ -156,8 +158,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
>  	case 2:
>  		if (nomem) {
>  			ipvs->drop_rate = ipvs->drop_counter
> -				= ipvs->sysctl_amemthresh /
> -				(ipvs->sysctl_amemthresh-availmem);
> +				= amemthresh /
> +				(amemthresh-availmem);
>  		} else {
>  			ipvs->drop_rate = 0;
>  			ipvs->sysctl_drop_packet = 1;

Regards

--
Julian Anastasov <ja@ssi.bg>