net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc

[ Upstream commit c5bf605ba4f9d6fbbb120595ab95002f4716edcb ]

This patch re-fix the issues mentioned by commit 22a825c541d7
("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 allows the cdc message sending but to check the
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@linux.alibaba.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 01bdb79..3c06625 100644 (file)
--- 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++;