netdev - Re: [PATCH net] net/smc: fix unexpected SMC_CLC_DECL_ERR

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Message-ID: <45837d14-7895-4aff-43a3-a5ad6ef80c2d@linux.alibaba.com>
Date:   Sat, 26 Feb 2022 00:45:06 +0800
From:   "D. Wythe" <alibuda@...ux.alibaba.com>
To:     kgraul@...ux.ibm.com
Cc:     kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [PATCH net] net/smc: fix unexpected SMC_CLC_DECL_ERR_REGRMB error



在 2022/2/25 下午4:11, D. Wythe 写道:
> From: "D. Wythe" <alibuda@...ux.alibaba.com>
> 
> Remove connections from link group is not synchronous with handling
> SMC_LLC_DELETE_RKEY, which means that even the number of connections is
> less that SMC_RMBS_PER_LGR_MAX, it does not mean that the connection can
> register rtoken successfully later, in other words, the rtoken entry may
> have not been released. This will cause an unexpected
> SMC_CLC_DECL_ERR_REGRMB to be reported, and then ths smc connection have
> to fallback to TCP.
> 
> Therefore, we need to judge according to the number of idle rtoken
> entry.
> 
> Fixes: cd6851f30386 ("smc: remote memory buffers (RMBs)")
> Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
> ---
>   net/smc/smc_core.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
> index 29525d0..24ef0af 100644
> --- a/net/smc/smc_core.c
> +++ b/net/smc/smc_core.c
> @@ -1864,7 +1864,8 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini)
>   		    (ini->smcd_version == SMC_V2 ||
>   		     lgr->vlan_id == ini->vlan_id) &&
>   		    (role == SMC_CLNT || ini->is_smcd ||
> -		     lgr->conns_num < SMC_RMBS_PER_LGR_MAX)) {
> +		     lgr->conns_num < SMC_RMBS_PER_LGR_MAX -
> +		     bitmap_weight(lgr->rtokens_used_mask, SMC_RMBS_PER_LGR_MAX))) {
>   			/* link group found */
>   			ini->first_contact_local = 0;
>   			conn->lgr = lgr;


I did a horrible math here, i'll send another fix later.

Best wishes.