[PATCH 4.14 24/42] net/smc: fix unexpected SMC_CLC_DECL_ERR_REGRMB error generated by client

Greg Kroah-Hartman
2022-03-07T09:24:16Z

From: D. Wythe <alibuda@linux.alibaba.com>

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>
---
net/smc/smc_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -239,8 +239,8 @@ void smc_conn_free(struct smc_connection
if (!lgr)
return;
smc_cdc_tx_dismiss_slots(conn);
- smc_lgr_unregister_conn(conn);
smc_buf_unuse(conn);
+ smc_lgr_unregister_conn(conn);
}

static void smc_link_clear(struct smc_link *lnk)