netdev - Re: [PATCH net-next 02/10] net/smc: fix SMC_CLC_DECL_ERR_REGRMB without smc_server_lgr

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Date:   Tue, 16 Aug 2022 15:58:44 +0800
From:   Tony Lu <tonylu@...ux.alibaba.com>
To:     "D. Wythe" <alibuda@...ux.alibaba.com>
Cc:     kgraul@...ux.ibm.com, wenjia@...ux.ibm.com, kuba@...nel.org,
        davem@...emloft.net, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [PATCH net-next 02/10] net/smc: fix SMC_CLC_DECL_ERR_REGRMB
 without smc_server_lgr_pending

On Thu, Aug 11, 2022 at 01:47:33AM +0800, D. Wythe wrote:
> From: "D. Wythe" <alibuda@...ux.alibaba.com>
> 
> As commit "net/smc: fix unexpected SMC_CLC_DECL_ERR_REGRMB error cause
> by server" mentioned, it works only when all connection creations are

This is a format issue, it's better to use:

commit 4940a1fdf31c ("net/smc: fix unexpected SMC_CLC_DECL_ERR_REGRMB
error cause by server").

> completely protected by smc_server_lgr_pending lock, since we already
> cancel the lock, we need to re-fix the issues.
> 
> Fixes: 4940a1fdf31c ("net/smc: fix unexpected SMC_CLC_DECL_ERR_REGRMB error cause by server")
> 
^^^ This blank line is unnecessary.

> Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
> ---
>  net/smc/af_smc.c   |  2 ++
>  net/smc/smc_core.c | 11 ++++++++---
>  net/smc/smc_core.h | 21 +++++++++++++++++++++
>  3 files changed, 31 insertions(+), 3 deletions(-)
> 
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index af4b0aa..c0842a9 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -2413,6 +2413,7 @@ static void smc_listen_work(struct work_struct *work)
>  		if (rc)
>  			goto out_unlock;
>  	}
> +	smc_conn_leave_rtoken_pending(new_smc, ini);
>  	smc_conn_save_peer_info(new_smc, cclc);
>  	smc_listen_out_connected(new_smc);
>  	SMC_STAT_SERV_SUCC_INC(sock_net(newclcsock->sk), ini);
> @@ -2422,6 +2423,7 @@ static void smc_listen_work(struct work_struct *work)
>  	if (ini->is_smcd)
>  		mutex_unlock(&smc_server_lgr_pending);
>  out_decl:
> +	smc_conn_leave_rtoken_pending(new_smc, ini);
>  	smc_listen_decline(new_smc, rc, ini ? ini->first_contact_local : 0,
>  			   proposal_version);
>  out_free:
> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
> index a3338cc..61a3854 100644
> --- a/net/smc/smc_core.c
> +++ b/net/smc/smc_core.c
> @@ -2190,14 +2190,19 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini)
>  		     lgr->vlan_id == ini->vlan_id) &&
>  		    (role == SMC_CLNT || ini->is_smcd ||
>  		    (lgr->conns_num < SMC_RMBS_PER_LGR_MAX &&
> -		      !bitmap_full(lgr->rtokens_used_mask, SMC_RMBS_PER_LGR_MAX)))) {
> +		    (SMC_RMBS_PER_LGR_MAX -
> +			bitmap_weight(lgr->rtokens_used_mask, SMC_RMBS_PER_LGR_MAX)
> +				> atomic_read(&lgr->rtoken_pendings))))) {
>  			/* link group found */
>  			ini->first_contact_local = 0;
>  			conn->lgr = lgr;
>  			rc = smc_lgr_register_conn(conn, false);
>  			write_unlock_bh(&lgr->conns_lock);
> -			if (!rc && delayed_work_pending(&lgr->free_work))
> -				cancel_delayed_work(&lgr->free_work);
> +			if (!rc) {
> +				smc_conn_enter_rtoken_pending(smc, ini);
> +				if (delayed_work_pending(&lgr->free_work))
> +					cancel_delayed_work(&lgr->free_work);
> +			}
>  			break;
>  		}
>  		write_unlock_bh(&lgr->conns_lock);
> diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
> index 199f533..acc2869 100644
> --- a/net/smc/smc_core.h
> +++ b/net/smc/smc_core.h
> @@ -293,6 +293,9 @@ struct smc_link_group {
>  	struct rb_root		conns_all;	/* connection tree */
>  	rwlock_t		conns_lock;	/* protects conns_all */
>  	unsigned int		conns_num;	/* current # of connections */
> +	atomic_t		rtoken_pendings;/* number of connection that
> +						 * lgr assigned but no rtoken got yet
> +						 */
>  	unsigned short		vlan_id;	/* vlan id of link group */
>  
>  	struct list_head	sndbufs[SMC_RMBE_SIZES];/* tx buffers */
> @@ -603,6 +606,24 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
>  int smcr_nl_get_link(struct sk_buff *skb, struct netlink_callback *cb);
>  int smcd_nl_get_lgr(struct sk_buff *skb, struct netlink_callback *cb);
>  
> +static inline void smc_conn_enter_rtoken_pending(struct smc_sock *smc, struct smc_init_info *ini)
> +{
> +	struct smc_link_group *lgr;

Consider this: struct smc_link_group *lgr = smc->conn.lgr ?

> +
> +	lgr = smc->conn.lgr;
> +	if (lgr && !ini->first_contact_local)
> +		atomic_inc(&lgr->rtoken_pendings);
> +}
> +
> +static inline void smc_conn_leave_rtoken_pending(struct smc_sock *smc, struct smc_init_info *ini)
> +{
> +	struct smc_link_group *lgr;

Ditto.

> +
> +	lgr = smc->conn.lgr;
> +	if (lgr && !ini->first_contact_local)
> +		atomic_dec(&lgr->rtoken_pendings);
> +}
> +
>  void smcr_lnk_cluster_on_lnk_state(struct smc_link *lnk);
>  
>  static inline struct smc_link_group *smc_get_lgr(struct smc_link *link)
> -- 
> 1.8.3.1