Re: [PATCH net-next v2 1/2] ipvs: add READ_ONCE barrier for ipvs->sysctl_amemthresh

[Julian Anastasov]

	Hello,

On Thu, 18 Apr 2024, Alexander Mikhalitsyn wrote:

> Cc: Julian Anastasov <ja@xxxxxx>
> Cc: Simon Horman <horms@xxxxxxxxxxxx>
> Cc: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> Cc: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx>
> Cc: Florian Westphal <fw@xxxxxxxxx>
> Suggested-by: Julian Anastasov <ja@xxxxxx>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
> ---
>  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@xxxxxx>