linux-kernel - Re: [PATCH net] net/smc: correct the reason code in smc_listen_find

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Date:   Tue, 17 Oct 2023 15:37:33 +0800
From:   Dust Li <dust.li@...ux.alibaba.com>
To:     Guangguan Wang <guangguan.wang@...ux.alibaba.com>,
        kgraul@...ux.ibm.com, wenjia@...ux.ibm.com, jaka@...ux.ibm.com,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com
Cc:     tonylu@...ux.alibaba.com, alibuda@...ux.alibaba.com,
        guwen@...ux.alibaba.com, linux-s390@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net/smc: correct the reason code in
 smc_listen_find_device when fallback

On Mon, Oct 16, 2023 at 02:11:53PM +0800, Guangguan Wang wrote:

Hi guangguan,

This patch doesn't apply clearly on net because it conflict with my
previous patch 4abbd2e3c1db(net/smc: return the right falback reason
when prefix checks fail), pls rebase.

>The function smc_find_ism_store_rc is not only used for ism, so it is
>reasonable to change the function name to smc_find_device_store_rc.
>
>The ini->rc is used to store the last error happened when finding usable
>ism or rdma device in smc_listen_find_device, and is set by calling smc_
>find_device_store_rc. Once the ini->rc is assigned to an none-zero value,
>the value can not be overwritten anymore. So the ini-rc should be set to
>the error reason only when an error actually occurs.
>
>When finding ISM/RDMA devices, device not found is not a real error, as
>not all machine have ISM/RDMA devices. Failures after device found, when
>initializing device or when initializing connection, is real errors, and
>should be store in ini->rc.
>
>SMC_CLC_DECL_DIFFPREFIX also is not a real error, as for SMC-RV2, it is
>not require same prefix.

I think it's better to seperate this patch into 2:
- one for changing the name from smc_find_ism_store_rc to smc_find_device_store_rc.
- one for fixing the return reason.

More comments below.

>
>Signed-off-by: Guangguan Wang <guangguan.wang@...ux.alibaba.com>
>---
> net/smc/af_smc.c | 23 +++++++++--------------
> 1 file changed, 9 insertions(+), 14 deletions(-)
>
>diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>index bacdd971615e..15d8ad7af75d 100644
>--- a/net/smc/af_smc.c
>+++ b/net/smc/af_smc.c
>@@ -2121,7 +2121,7 @@ static void smc_check_ism_v2_match(struct smc_init_info *ini,
> 	}
> }
> 
>-static void smc_find_ism_store_rc(u32 rc, struct smc_init_info *ini)
>+static void smc_find_device_store_rc(u32 rc, struct smc_init_info *ini)
> {
> 	if (!ini->rc)
> 		ini->rc = rc;
>@@ -2162,10 +2162,8 @@ static void smc_find_ism_v2_device_serv(struct smc_sock *new_smc,
> 	}
> 	mutex_unlock(&smcd_dev_list.mutex);
> 
>-	if (!ini->ism_dev[0]) {
>-		smc_find_ism_store_rc(SMC_CLC_DECL_NOSMCD2DEV, ini);
>+	if (!ini->ism_dev[0])
> 		goto not_found;
>-	}
> 
> 	smc_ism_get_system_eid(&eid);
> 	if (!smc_clc_match_eid(ini->negotiated_eid, smc_v2_ext,
>@@ -2180,7 +2178,7 @@ static void smc_find_ism_v2_device_serv(struct smc_sock *new_smc,
> 		ini->ism_selected = i;
> 		rc = smc_listen_ism_init(new_smc, ini);
> 		if (rc) {
>-			smc_find_ism_store_rc(rc, ini);
>+			smc_find_device_store_rc(rc, ini);
> 			/* try next active ISM device */
> 			continue;
> 		}
>@@ -2213,11 +2211,12 @@ static void smc_find_ism_v1_device_serv(struct smc_sock *new_smc,
> 		goto not_found;
> 	ini->ism_selected = 0;
> 	rc = smc_listen_ism_init(new_smc, ini);
>-	if (!rc)
>+	if (!rc) {
>+		smc_find_device_store_rc(rc, ini);

This smc_find_device_store_rc() seems useless when rc == 0 here ?

> 		return;		/* V1 ISM device found */
>+	}
> 
> not_found:
>-	smc_find_ism_store_rc(rc, ini);
> 	ini->smcd_version &= ~SMC_V1;
> 	ini->ism_dev[0] = NULL;
> 	ini->is_smcd = false;
>@@ -2266,10 +2265,8 @@ static void smc_find_rdma_v2_device_serv(struct smc_sock *new_smc,
> 	ini->smcrv2.saddr = new_smc->clcsock->sk->sk_rcv_saddr;
> 	ini->smcrv2.daddr = smc_ib_gid_to_ipv4(smc_v2_ext->roce);
> 	rc = smc_find_rdma_device(new_smc, ini);
>-	if (rc) {
>-		smc_find_ism_store_rc(rc, ini);
>+	if (rc)
> 		goto not_found;
>-	}
> 	if (!ini->smcrv2.uses_gateway)
> 		memcpy(ini->smcrv2.nexthop_mac, pclc->lcl.mac, ETH_ALEN);
> 
>@@ -2284,7 +2281,7 @@ static void smc_find_rdma_v2_device_serv(struct smc_sock *new_smc,
> 	if (!rc)
> 		return;
> 	ini->smcr_version = smcr_version;
>-	smc_find_ism_store_rc(rc, ini);
>+	smc_find_device_store_rc(rc, ini);
> 
> not_found:
> 	ini->smcr_version &= ~SMC_V2;
>@@ -2330,8 +2327,6 @@ static int smc_listen_find_device(struct smc_sock *new_smc,
> 
> 	/* check for matching IP prefix and subnet length (V1) */
> 	prfx_rc = smc_listen_prfx_check(new_smc, pclc);
>-	if (prfx_rc)
>-		smc_find_ism_store_rc(prfx_rc, ini);
> 
> 	/* get vlan id from IP device */
> 	if (smc_vlan_by_tcpsk(new_smc->clcsock, ini))
>@@ -2358,7 +2353,7 @@ static int smc_listen_find_device(struct smc_sock *new_smc,
> 		int rc;
> 
> 		rc = smc_find_rdma_v1_device_serv(new_smc, pclc, ini);
>-		smc_find_ism_store_rc(rc, ini);
>+		smc_find_device_store_rc(rc, ini);
> 		return (!rc) ? 0 : ini->rc;
> 	}
> 	return SMC_CLC_DECL_NOSMCDEV;
>-- 
>2.24.3 (Apple Git-128)