rds: Use {READ,WRITE}_ONCE for heartbeat start and state

The heartbeat mechanism has a time-stamp and a state that are accessed
from different contexts without any synchronization. Hence add proper
{READ,WRITE}_ONCE().

Orabug: 30418039

Signed-off-by: Håkon Bugge <[email protected]>
Reviewed-by: Ka-Cheong Poon <[email protected]>
Tested-by: Michael Nowak <[email protected]>

---

v1->v2:
	* Added Ka-Cheong's r-b
	* Added Mike's t-b

Signed-off-by: Somasundaram Krishnasamy <[email protected]>

Orabug: 30820081

UEK5 => UEK6

(cherry picked from commit 9022896)
cherry-pick-repo=UEK/production/linux-uek.git

Signed-off-by: Gerd Rausch <[email protected]>
Reviewed-by: Sharon Liu <[email protected]>

Author: Hakon-Bugge

net/rds/recv.c

@@ -699,7 +699,7 @@ rds_recv_local(struct rds_conn_path *cp, struct in6_addr *saddr,
 			rds_send_hb(conn, 1);
 		} else if (is_hb_pong) {
 			rds_stats_inc(s_recv_hb_pong);
-			cp->cp_hb_start = 0;
+			WRITE_ONCE(cp->cp_hb_start, 0);
 		} else {
 			if (be16_to_cpu(inc->i_hdr.h_sport) == RDS_FLAG_PROBE_PORT)
 				rds_stats_inc(s_recv_mprds_ping);

net/rds/threads.c

@@ -124,8 +124,8 @@ void rds_connect_path_complete(struct rds_conn_path *cp, int curr)
 	rds_cond_queue_send_work(cp, 0);
 	rds_clear_queued_recv_work_bit(cp);
 	rds_cond_queue_recv_work(cp, 0);
-	cp->cp_hb_start = 0;
-	cp->cp_hb_state = HB_PONG_RCVD;
+	WRITE_ONCE(cp->cp_hb_start, 0);
+	WRITE_ONCE(cp->cp_hb_state, HB_PONG_RCVD);
 	queue_delayed_work(cp->cp_wq, &cp->cp_hb_w, 0);
 	cancel_delayed_work(&cp->cp_reconn_w);
 
@@ -341,18 +341,18 @@ void rds_hb_worker(struct work_struct *work)
 		return;
 
 	if (rds_conn_path_state(cp) == RDS_CONN_UP) {
-		switch (cp->cp_hb_state) {
+		switch (READ_ONCE(cp->cp_hb_state)) {
 		case HB_PING_SENT:
-			if (!cp->cp_hb_start) {
-				cp->cp_hb_state = HB_PONG_RCVD;
+			if (!READ_ONCE(cp->cp_hb_start)) {
+				WRITE_ONCE(cp->cp_hb_state, HB_PONG_RCVD);
 				/* Pseudo random from 50% to 150% of interval */
 				delay = msecs_to_jiffies(rds_sysctl_conn_hb_interval * 1000 / 2) +
 					msecs_to_jiffies(prandom_u32() % rds_sysctl_conn_hb_interval * 1000);
-			} else if (now - cp->cp_hb_start > rds_sysctl_conn_hb_timeout) {
+			} else if (now - READ_ONCE(cp->cp_hb_start) > rds_sysctl_conn_hb_timeout) {
 				rds_rtd_ptr(RDS_RTD_CM,
 					    "RDS/IB: connection <%pI6c,%pI6c,%d> timed out (0x%lx,0x%lx)..discon and recon\n",
 					    &conn->c_laddr, &conn->c_faddr,
-					    conn->c_tos, cp->cp_hb_start, now);
+					    conn->c_tos, READ_ONCE(cp->cp_hb_start), now);
 				rds_conn_path_drop(cp, DR_HB_TIMEOUT);
 				return;
 			}
@@ -367,8 +367,8 @@ void rds_hb_worker(struct work_struct *work)
 					ret);
 				return;
 			}
-			cp->cp_hb_start = now;
-			cp->cp_hb_state = HB_PING_SENT;
+			WRITE_ONCE(cp->cp_hb_start, now);
+			WRITE_ONCE(cp->cp_hb_state, HB_PING_SENT);
 			break;
 		}