Re: [PATCH net-next 2/2] net/smc: add sysctl for max conns per lgr for SMC-R v2.1

[Jan Karcher <jaka@linux.ibm.com>]

On 22/11/2023 14:52, Guangguan Wang wrote:
> Add a new sysctl: net.smc.smcr_max_conns_per_lgr, which is
> used to control the preferred max connections per lgr for
> SMC-R v2.1. The default value of this sysctl is 255, and
> the acceptable value ranges from 16 to 255.
> 
> Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>

Hi Guangguan,
thanks for your Submission.

Reviewed-by: Jan Karcher <jaka@linux.ibm.com>

> ---
>   Documentation/networking/smc-sysctl.rst |  6 ++++++
>   include/net/netns/smc.h                 |  1 +
>   net/smc/smc_clc.c                       |  5 +++--
>   net/smc/smc_sysctl.c                    | 12 ++++++++++++
>   net/smc/smc_sysctl.h                    |  1 +
>   5 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/networking/smc-sysctl.rst b/Documentation/networking/smc-sysctl.rst
> index c6ef86ef4c4f..a874d007f2db 100644
> --- a/Documentation/networking/smc-sysctl.rst
> +++ b/Documentation/networking/smc-sysctl.rst
> @@ -65,3 +65,9 @@ smcr_max_links_per_lgr - INTEGER
>   	for SMC-R v2.1 and later.
>   
>   	Default: 2
> +
> +smcr_max_conns_per_lgr - INTEGER
> +	Controls the max number of connections can be added to a SMC-R link group. The
> +	acceptable value ranges from 16 to 255. Only for SMC-R v2.1 and later.
> +
> +	Default: 255
> diff --git a/include/net/netns/smc.h b/include/net/netns/smc.h
> index da7023587824..fc752a50f91b 100644
> --- a/include/net/netns/smc.h
> +++ b/include/net/netns/smc.h
> @@ -23,5 +23,6 @@ struct netns_smc {
>   	int				sysctl_wmem;
>   	int				sysctl_rmem;
>   	int				sysctl_max_links_per_lgr;
> +	int				sysctl_max_conns_per_lgr;
>   };
>   #endif
> diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
> index 1f87c8895a27..0fda5156eef0 100644
> --- a/net/smc/smc_clc.c
> +++ b/net/smc/smc_clc.c
> @@ -944,7 +944,7 @@ int smc_clc_send_proposal(struct smc_sock *smc, struct smc_init_info *ini)
>   	}
>   	if (smcr_indicated(ini->smc_type_v2)) {
>   		memcpy(v2_ext->roce, ini->smcrv2.ib_gid_v2, SMC_GID_SIZE);
> -		v2_ext->max_conns = SMC_CONN_PER_LGR_PREFER;
> +		v2_ext->max_conns = net->smc.sysctl_max_conns_per_lgr;
>   		v2_ext->max_links = net->smc.sysctl_max_links_per_lgr;
>   	}
>   
> @@ -1191,7 +1191,8 @@ int smc_clc_srv_v2x_features_validate(struct smc_sock *smc,
>   		return SMC_CLC_DECL_NOV2EXT;
>   
>   	if (ini->smcr_version & SMC_V2) {
> -		ini->max_conns = min_t(u8, pclc_v2_ext->max_conns, SMC_CONN_PER_LGR_PREFER);
> +		ini->max_conns = min_t(u8, pclc_v2_ext->max_conns,
> +				       net->smc.sysctl_max_conns_per_lgr);
>   		if (ini->max_conns < SMC_CONN_PER_LGR_MIN)
>   			return SMC_CLC_DECL_MAXCONNERR;
>   
> diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
> index 3e9bb921e40a..a5946d1b9d60 100644
> --- a/net/smc/smc_sysctl.c
> +++ b/net/smc/smc_sysctl.c
> @@ -27,6 +27,8 @@ static const int net_smc_wmem_init = (64 * 1024);
>   static const int net_smc_rmem_init = (64 * 1024);
>   static int links_per_lgr_min = SMC_LINKS_ADD_LNK_MIN;
>   static int links_per_lgr_max = SMC_LINKS_ADD_LNK_MAX;
> +static int conns_per_lgr_min = SMC_CONN_PER_LGR_MIN;
> +static int conns_per_lgr_max = SMC_CONN_PER_LGR_MAX;
>   
>   static struct ctl_table smc_table[] = {
>   	{
> @@ -79,6 +81,15 @@ static struct ctl_table smc_table[] = {
>   		.extra1		= &links_per_lgr_min,
>   		.extra2		= &links_per_lgr_max,
>   	},
> +	{
> +		.procname	= "smcr_max_conns_per_lgr",
> +		.data		= &init_net.smc.sysctl_max_conns_per_lgr,
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= &conns_per_lgr_min,
> +		.extra2		= &conns_per_lgr_max,
> +	},
>   	{  }
>   };
>   
> @@ -109,6 +120,7 @@ int __net_init smc_sysctl_net_init(struct net *net)
>   	WRITE_ONCE(net->smc.sysctl_wmem, net_smc_wmem_init);
>   	WRITE_ONCE(net->smc.sysctl_rmem, net_smc_rmem_init);
>   	net->smc.sysctl_max_links_per_lgr = SMC_LINKS_PER_LGR_MAX_PREFER;
> +	net->smc.sysctl_max_conns_per_lgr = SMC_CONN_PER_LGR_PREFER;
>   
>   	return 0;
>   
> diff --git a/net/smc/smc_sysctl.h b/net/smc/smc_sysctl.h
> index 5783dd7575dd..eb2465ae1e15 100644
> --- a/net/smc/smc_sysctl.h
> +++ b/net/smc/smc_sysctl.h
> @@ -24,6 +24,7 @@ static inline int smc_sysctl_net_init(struct net *net)
>   {
>   	net->smc.sysctl_autocorking_size = SMC_AUTOCORKING_DEFAULT_SIZE;
>   	net->smc.sysctl_max_links_per_lgr = SMC_LINKS_PER_LGR_MAX_PREFER;
> +	net->smc.sysctl_max_conns_per_lgr = SMC_CONN_PER_LGR_PREFER;
>   	return 0;
>   }
>