net/smc: calculate write offset in RMB only once per connection

Currently, the write offset within the RMB is calculated on each write
operation although it is fixed for each connection. With this patch, the
offset is calculated once and stored in a connection specific variable.
Signed-off-by: NHans Wippel <hwippel@linux.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/smc/af_smc.c

@@ -377,10 +377,13 @@ static int smc_clnt_conf_first_link(struct smc_sock *smc)
 static void smc_conn_save_peer_info(struct smc_sock *smc,
 				    struct smc_clc_msg_accept_confirm *clc)
 {
+	int bufsize = smc_uncompress_bufsize(clc->rmbe_size);
+
 	smc->conn.peer_rmbe_idx = clc->rmbe_idx;
 	smc->conn.local_tx_ctrl.token = ntohl(clc->rmbe_alert_token);
-	smc->conn.peer_rmbe_size = smc_uncompress_bufsize(clc->rmbe_size);
+	smc->conn.peer_rmbe_size = bufsize;
 	atomic_set(&smc->conn.peer_rmbe_space, smc->conn.peer_rmbe_size);
+	smc->conn.tx_off = bufsize * (smc->conn.peer_rmbe_idx - 1);
 }
 
 static void smc_link_save_peer_info(struct smc_link *link,

net/smc/smc.h

@@ -151,6 +151,7 @@ struct smc_connection {
 	u16			tx_cdc_seq;	/* sequence # for CDC send */
 	spinlock_t		send_lock;	/* protect wr_sends */
 	struct delayed_work	tx_work;	/* retry of smc_cdc_msg_send */
+	u32			tx_off;		/* base offset in peer rmb */
 
 	struct smc_host_cdc_msg	local_rx_ctrl;	/* filled during event_handl.
 						 * .prod cf. TCP rcv_nxt

net/smc/smc_tx.c

@@ -261,7 +261,7 @@ static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 	rdma_wr.remote_addr =
 		lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 		/* RMBE within RMB */
-		((conn->peer_rmbe_idx - 1) * conn->peer_rmbe_size) +
+		conn->tx_off +
 		/* offset within RMBE */
 		peer_rmbe_offset;
 	rdma_wr.rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;