Patch "net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-smc-allow-cdc-msg-send-rather-than-drop-it-with-.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9ca530bf318c3f03e27206c5ba4a43ae55e52ff6
Author: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>
Date:   Fri Nov 3 14:07:39 2023 +0800

    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@xxxxxxxxxxxxxxxxx>
    Reviewed-by: Dust Li <dust.li@xxxxxxxxxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 0823961ec2e63..1df7557362673 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 */
@@ -104,9 +106,6 @@ 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++;