net/smc: fix unexpected SMC_CLC_DECL_ERR_REGRMB error generated by client

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>

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index e7a6c8dcf6b8e9a6e2cccac86d0f3c3a1207279b..59baa53201c50e0f5ab75ef5bac394235f402588 100644 (file)
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -321,8 +321,8 @@ void smc_conn_free(struct smc_connection *conn)
        } else {
                smc_cdc_tx_dismiss_slots(conn);
        }
-       smc_lgr_unregister_conn(conn);          /* unsets conn->lgr */
        smc_buf_unuse(conn, lgr);               /* allow buffer reuse */
+       smc_lgr_unregister_conn(conn);          /* unsets conn->lgr */
 
        if (!lgr->conns_num)
                smc_lgr_schedule_free_work(lgr);