netdev - Re: [PATCH net 2/3] net/smc: allow cdc msg send rather than drop it with NULL sndbuf

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Date: Wed, 1 Nov 2023 16:19:16 +0800
From: Dust Li <dust.li@...ux.alibaba.com>
To: "D. Wythe" <alibuda@...ux.alibaba.com>, kgraul@...ux.ibm.com,
	wenjia@...ux.ibm.com, jaka@...ux.ibm.com, wintera@...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 2/3] net/smc: allow cdc msg send rather than drop it
 with NULL sndbuf_desc

On Wed, Nov 01, 2023 at 11:42:56AM +0800, D. Wythe wrote:
>From: "D. Wythe" <alibuda@...ux.alibaba.com>
>
>This patch re-fix the issues memtianed by commit 22a825c541d7

memtianed -> mentioned ?

>("net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler()").
>
>Blocking sending message do solve the issues though, but it also
>prevents the peer to receive the final message. Besides, in logic,
>whether the sndbuf_desc is NULL or not have no impact on the processing
>of cdc message sending.
>
>Hence that, this patch allow the cdc message sending but to check the
allows

>sndbuf_desc with care in smc_cdc_tx_handler().
>
>Fixes: 22a825c541d7 ("net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler()")
>Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
>Reviewed-by: Wenjia Zhang <wenjia@...ux.ibm.com>

Reviewed-by: Dust Li <dust.li@...ux.alibaba.com>

>---
> net/smc/smc_cdc.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
>diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
>index 01bdb79..3c06625 100644
>--- a/net/smc/smc_cdc.c
>+++ b/net/smc/smc_cdc.c
>@@ -28,13 +28,15 @@ static void smc_cdc_tx_handler(struct smc_wr_tx_pend_priv *pnd_snd,
> {
> 	struct smc_cdc_tx_pend *cdcpend = (struct smc_cdc_tx_pend *)pnd_snd;
> 	struct smc_connection *conn = cdcpend->conn;
>+	struct smc_buf_desc *sndbuf_desc;
> 	struct smc_sock *smc;
> 	int diff;
> 
>+	sndbuf_desc = conn->sndbuf_desc;
> 	smc = container_of(conn, struct smc_sock, conn);
> 	bh_lock_sock(&smc->sk);
>-	if (!wc_status) {
>-		diff = smc_curs_diff(cdcpend->conn->sndbuf_desc->len,
>+	if (!wc_status && sndbuf_desc) {
>+		diff = smc_curs_diff(sndbuf_desc->len,
> 				     &cdcpend->conn->tx_curs_fin,
> 				     &cdcpend->cursor);
> 		/* sndbuf_space is decreased in smc_sendmsg */
>@@ -114,9 +116,6 @@ int smc_cdc_msg_send(struct smc_connection *conn,
> 	union smc_host_cursor cfed;
> 	int rc;
> 
>-	if (unlikely(!READ_ONCE(conn->sndbuf_desc)))
>-		return -ENOBUFS;
>-
> 	smc_cdc_add_pending_send(conn, pend);
> 
> 	conn->tx_cdc_seq++;
>-- 
>1.8.3.1