The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9ebb0c4b27a6158303b791b5b91e66d7665ee30e Mon Sep 17 00:00:00 2001

From: Guo DaXing guodaxing@huawei.com Date: Wed, 24 Nov 2021 13:32:38 +0100 Subject: [PATCH] net/smc: Fix loop in smc_listen

The kernel_listen function in smc_listen will fail when all the available ports are occupied. At this point smc->clcsock->sk->sk_data_ready has been changed to smc_clcsock_data_ready. When we call smc_listen again, now both smc->clcsock->sk->sk_data_ready and smc->clcsk_data_ready point to the smc_clcsock_data_ready function.

The smc_clcsock_data_ready() function calls lsmc->clcsk_data_ready which now points to itself resulting in an infinite loop.

This patch restores smc->clcsock->sk->sk_data_ready with the old value.

Fixes: a60a2b1e0af1 ("net/smc: reduce active tcp_listen workers") Signed-off-by: Guo DaXing guodaxing@huawei.com Acked-by: Tony Lu tonylu@linux.alibaba.com Signed-off-by: Karsten Graul kgraul@linux.ibm.com Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index 2692cba5a7b6..4b62c925a13e 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -2134,8 +2134,10 @@ static int smc_listen(struct socket *sock, int backlog) smc->clcsock->sk->sk_user_data = (void *)((uintptr_t)smc | SK_USER_DATA_NOCOPY); rc = kernel_listen(smc->clcsock, backlog); - if (rc) + if (rc) { + smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready; goto out; + } sk->sk_max_ack_backlog = backlog; sk->sk_ack_backlog = 0; sk->sk_state = SMC_LISTEN;