net/smc: fix unexpected SMC_CLC_DECL_ERR_REGRMB error generated by client

BugLink: https://bugs.launchpad.net/bugs/1964361
commit 0537f0a2151375dcf90c1bbfda6a0aaf57164e89 upstream.

The main reason for this unexpected SMC_CLC_DECL_ERR_REGRMB in client
dues to following execution sequence:

Server Conn A:           Server Conn B:			Client Conn B:

smc_lgr_unregister_conn
                        smc_lgr_register_conn
                        smc_clc_send_accept     ->
                                                        smc_rtoken_add
smcr_buf_unuse
		->		Client Conn A:
				smc_rtoken_delete

smc_lgr_unregister_conn() makes current link available to assigned to new
incoming connection, while smcr_buf_unuse() has not executed yet, which
means that smc_rtoken_add may fail because of insufficient rtoken_entry,
reversing their execution order will avoid this problem.

Fixes: 3e034725c0d8 ("net/smc: common functions for RMBs and send buffers")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 36e93a3f284d0f763bd5894cf361525c0ef1701d..0bb17a105de7729c7441d8b852b63df7d432e74e 100644 (file)
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1061,8 +1061,8 @@ void smc_conn_free(struct smc_connection *conn)
                        cancel_work_sync(&conn->abort_work);
        }
        if (!list_empty(&lgr->list)) {
-               smc_lgr_unregister_conn(conn);
                smc_buf_unuse(conn, lgr); /* allow buffer reuse */
+               smc_lgr_unregister_conn(conn);
        }
 
        if (!lgr->conns_num)