locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

12 files changed, 18 insertions, 18 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 11596a302a26..61559ca3980b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3725,7 +3725,7 @@ bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index,
 	flow_table = rcu_dereference(rxqueue->rps_flow_table);
 	if (flow_table && flow_id <= flow_table->mask) {
 		rflow = &flow_table->flows[flow_id];
-		cpu = ACCESS_ONCE(rflow->cpu);
+		cpu = READ_ONCE(rflow->cpu);
 		if (rflow->filter == filter_id && cpu < nr_cpu_ids &&
 		    ((int)(per_cpu(softnet_data, cpu).input_queue_head -
 			   rflow->last_qtail) <
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 6e1e10ff433a..3b2034f6d49d 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3377,7 +3377,7 @@ static void pktgen_wait_for_skb(struct pktgen_dev *pkt_dev)
 
 static void pktgen_xmit(struct pktgen_dev *pkt_dev)
 {
-	unsigned int burst = ACCESS_ONCE(pkt_dev->burst);
+	unsigned int burst = READ_ONCE(pkt_dev->burst);
 	struct net_device *odev = pkt_dev->odev;
 	struct netdev_queue *txq;
 	struct sk_buff *skb;
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index af74d0433453..f9597ba26599 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -164,7 +164,7 @@ static void inet_frag_worker(struct work_struct *work)
 
 	local_bh_disable();
 
-	for (i = ACCESS_ONCE(f->next_bucket); budget; --budget) {
+	for (i = READ_ONCE(f->next_bucket); budget; --budget) {
 		evicted += inet_evict_bucket(f, &f->hash[i]);
 		i = (i + 1) & (INETFRAGS_HASHSZ - 1);
 		if (evicted > INETFRAGS_EVICT_MAX)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 3d9f1c2f81c5..c0864562083b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -495,7 +495,7 @@ u32 ip_idents_reserve(u32 hash, int segs)
 {
 	u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ;
 	atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
-	u32 old = ACCESS_ONCE(*p_tstamp);
+	u32 old = READ_ONCE(*p_tstamp);
 	u32 now = (u32)jiffies;
 	u32 new, delta = 0;
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 0bc9e46a5369..48531da1aba6 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1908,7 +1908,7 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
 	if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len))
 		goto send_now;
 
-	win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor);
+	win_divisor = READ_ONCE(sysctl_tcp_tso_win_divisor);
 	if (win_divisor) {
 		u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache);
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ebfbccae62fd..02ec9a349303 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1853,7 +1853,7 @@ static int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		 */
 
 		/* if we're overly short, let UDP handle it */
-		encap_rcv = ACCESS_ONCE(up->encap_rcv);
+		encap_rcv = READ_ONCE(up->encap_rcv);
 		if (encap_rcv) {
 			int ret;
 
@@ -2298,7 +2298,7 @@ void udp_destroy_sock(struct sock *sk)
 	unlock_sock_fast(sk, slow);
 	if (static_key_false(&udp_encap_needed) && up->encap_type) {
 		void (*encap_destroy)(struct sock *sk);
-		encap_destroy = ACCESS_ONCE(up->encap_destroy);
+		encap_destroy = READ_ONCE(up->encap_destroy);
 		if (encap_destroy)
 			encap_destroy(sk);
 	}
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index a1c24443cd9e..dab946554157 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -490,7 +490,7 @@ ip6_tnl_err(struct sk_buff *skb, __u8 ipproto, struct inet6_skb_parm *opt,
 	if (!t)
 		goto out;
 
-	tproto = ACCESS_ONCE(t->parms.proto);
+	tproto = READ_ONCE(t->parms.proto);
 	if (tproto != ipproto && tproto != 0)
 		goto out;
 
@@ -899,7 +899,7 @@ static int ipxip6_rcv(struct sk_buff *skb, u8 ipproto,
 	t = ip6_tnl_lookup(dev_net(skb->dev), &ipv6h->saddr, &ipv6h->daddr);
 
 	if (t) {
-		u8 tproto = ACCESS_ONCE(t->parms.proto);
+		u8 tproto = READ_ONCE(t->parms.proto);
 
 		if (tproto != ipproto && tproto != 0)
 			goto drop;
@@ -1233,7 +1233,7 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
 
-	tproto = ACCESS_ONCE(t->parms.proto);
+	tproto = READ_ONCE(t->parms.proto);
 	if (tproto != IPPROTO_IPIP && tproto != 0)
 		return -1;
 
@@ -1303,7 +1303,7 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
 	u8 tproto;
 	int err;
 
-	tproto = ACCESS_ONCE(t->parms.proto);
+	tproto = READ_ONCE(t->parms.proto);
 	if ((tproto != IPPROTO_IPV6 && tproto != 0) ||
 	    ip6_tnl_addr_conflict(t, ipv6h))
 		return -1;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 40d7234c27b9..3f30fa313bf2 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -606,7 +606,7 @@ static int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		 */
 
 		/* if we're overly short, let UDP handle it */
-		encap_rcv = ACCESS_ONCE(up->encap_rcv);
+		encap_rcv = READ_ONCE(up->encap_rcv);
 		if (encap_rcv) {
 			int ret;
 
@@ -1432,7 +1432,7 @@ void udpv6_destroy_sock(struct sock *sk)
 
 	if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
 		void (*encap_destroy)(struct sock *sk);
-		encap_destroy = ACCESS_ONCE(up->encap_destroy);
+		encap_destroy = READ_ONCE(up->encap_destroy);
 		if (encap_destroy)
 			encap_destroy(sk);
 	}
diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c
index dd3e83328ad5..82cb93f66b9b 100644
--- a/net/llc/llc_input.c
+++ b/net/llc/llc_input.c
@@ -193,7 +193,7 @@ int llc_rcv(struct sk_buff *skb, struct net_device *dev,
 	 */
 	rcv = rcu_dereference(sap->rcv_func);
 	dest = llc_pdu_type(skb);
-	sap_handler = dest ? ACCESS_ONCE(llc_type_handlers[dest - 1]) : NULL;
+	sap_handler = dest ? READ_ONCE(llc_type_handlers[dest - 1]) : NULL;
 	if (unlikely(!sap_handler)) {
 		if (rcv)
 			rcv(skb, dev, pt, orig_dev);
@@ -214,7 +214,7 @@ drop:
 	kfree_skb(skb);
 	goto out;
 handle_station:
-	sta_handler = ACCESS_ONCE(llc_station_handler);
+	sta_handler = READ_ONCE(llc_station_handler);
 	if (!sta_handler)
 		goto drop;
 	sta_handler(skb);
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 69615016d5bf..214d2ba02877 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -2008,7 +2008,7 @@ static void sta_stats_decode_rate(struct ieee80211_local *local, u16 rate,
 
 static int sta_set_rate_info_rx(struct sta_info *sta, struct rate_info *rinfo)
 {
-	u16 rate = ACCESS_ONCE(sta_get_last_rx_stats(sta)->last_rate);
+	u16 rate = READ_ONCE(sta_get_last_rx_stats(sta)->last_rate);
 
 	if (rate == STA_STATS_RATE_INVALID)
 		return -EINVAL;
diff --git a/net/netlabel/netlabel_calipso.c b/net/netlabel/netlabel_calipso.c
index d177dd066504..4d748975117d 100644
--- a/net/netlabel/netlabel_calipso.c
+++ b/net/netlabel/netlabel_calipso.c
@@ -393,7 +393,7 @@ EXPORT_SYMBOL(netlbl_calipso_ops_register);
 
 static const struct netlbl_calipso_ops *netlbl_calipso_ops_get(void)
 {
-	return ACCESS_ONCE(calipso_ops);
+	return READ_ONCE(calipso_ops);
 }
 
 /**
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index d396cb61a280..eb866647a27a 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -14201,7 +14201,7 @@ static bool __nl80211_unexpected_frame(struct net_device *dev, u8 cmd,
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
 	struct sk_buff *msg;
 	void *hdr;
-	u32 nlportid = ACCESS_ONCE(wdev->ap_unexpected_nlportid);
+	u32 nlportid = READ_ONCE(wdev->ap_unexpected_nlportid);
 
 	if (!nlportid)
 		return false;