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>

drivers/net/ethernet/intel/i40e/i40e_debugfs.c

@@ -264,7 +264,7 @@ static void i40e_dbg_dump_vsi_seid(struct i40e_pf *pf, int seid)
 		 vsi->rx_buf_failed, vsi->rx_page_failed);
 	rcu_read_lock();
 	for (i = 0; i < vsi->num_queue_pairs; i++) {
-		struct i40e_ring *rx_ring = ACCESS_ONCE(vsi->rx_rings[i]);
+		struct i40e_ring *rx_ring = READ_ONCE(vsi->rx_rings[i]);
 
 		if (!rx_ring)
 			continue;
@@ -320,7 +320,7 @@ static void i40e_dbg_dump_vsi_seid(struct i40e_pf *pf, int seid)
 			 ITR_IS_DYNAMIC(rx_ring->rx_itr_setting) ? "dynamic" : "fixed");
 	}
 	for (i = 0; i < vsi->num_queue_pairs; i++) {
-		struct i40e_ring *tx_ring = ACCESS_ONCE(vsi->tx_rings[i]);
+		struct i40e_ring *tx_ring = READ_ONCE(vsi->tx_rings[i]);
 
 		if (!tx_ring)
 			continue;

drivers/net/ethernet/intel/i40e/i40e_ethtool.c

@@ -1570,7 +1570,7 @@ static void i40e_get_ethtool_stats(struct net_device *netdev,
 	}
 	rcu_read_lock();
 	for (j = 0; j < vsi->num_queue_pairs; j++) {
-		tx_ring = ACCESS_ONCE(vsi->tx_rings[j]);
+		tx_ring = READ_ONCE(vsi->tx_rings[j]);
 
 		if (!tx_ring)
 			continue;

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -455,7 +455,7 @@ static void i40e_get_netdev_stats_struct(struct net_device *netdev,
 		u64 bytes, packets;
 		unsigned int start;
 
-		tx_ring = ACCESS_ONCE(vsi->tx_rings[i]);
+		tx_ring = READ_ONCE(vsi->tx_rings[i]);
 		if (!tx_ring)
 			continue;
 		i40e_get_netdev_stats_struct_tx(tx_ring, stats);
@@ -791,7 +791,7 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi)
 	rcu_read_lock();
 	for (q = 0; q < vsi->num_queue_pairs; q++) {
 		/* locate Tx ring */
-		p = ACCESS_ONCE(vsi->tx_rings[q]);
+		p = READ_ONCE(vsi->tx_rings[q]);
 
 		do {
 			start = u64_stats_fetch_begin_irq(&p->syncp);

drivers/net/ethernet/intel/i40e/i40e_ptp.c

@@ -130,7 +130,7 @@ static int i40e_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
 	}
 
 	smp_mb(); /* Force any pending update before accessing. */
-	adj = ACCESS_ONCE(pf->ptp_base_adj);
+	adj = READ_ONCE(pf->ptp_base_adj);
 
 	freq = adj;
 	freq *= ppb;
@@ -499,7 +499,7 @@ void i40e_ptp_set_increment(struct i40e_pf *pf)
 	wr32(hw, I40E_PRTTSYN_INC_H, incval >> 32);
 
 	/* Update the base adjustement value. */
-	ACCESS_ONCE(pf->ptp_base_adj) = incval;
+	WRITE_ONCE(pf->ptp_base_adj, incval);
 	smp_mb(); /* Force the above update. */
 }
 

drivers/net/ethernet/intel/igb/e1000_regs.h

@@ -375,7 +375,7 @@ u32 igb_rd32(struct e1000_hw *hw, u32 reg);
 /* write operations, indexed using DWORDS */
 #define wr32(reg, val) \
 do { \
-	u8 __iomem *hw_addr = ACCESS_ONCE((hw)->hw_addr); \
+	u8 __iomem *hw_addr = READ_ONCE((hw)->hw_addr); \
 	if (!E1000_REMOVED(hw_addr)) \
 		writel((val), &hw_addr[(reg)]); \
 } while (0)

drivers/net/ethernet/intel/igb/igb_main.c

@@ -750,7 +750,7 @@ static void igb_cache_ring_register(struct igb_adapter *adapter)
 u32 igb_rd32(struct e1000_hw *hw, u32 reg)
 {
 	struct igb_adapter *igb = container_of(hw, struct igb_adapter, hw);
-	u8 __iomem *hw_addr = ACCESS_ONCE(hw->hw_addr);
+	u8 __iomem *hw_addr = READ_ONCE(hw->hw_addr);
 	u32 value = 0;
 
 	if (E1000_REMOVED(hw_addr))

drivers/net/ethernet/intel/ixgbe/ixgbe_common.h

@@ -161,7 +161,7 @@ static inline bool ixgbe_removed(void __iomem *addr)
 
 static inline void ixgbe_write_reg(struct ixgbe_hw *hw, u32 reg, u32 value)
 {
-	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
+	u8 __iomem *reg_addr = READ_ONCE(hw->hw_addr);
 
 	if (ixgbe_removed(reg_addr))
 		return;
@@ -180,7 +180,7 @@ static inline void writeq(u64 val, void __iomem *addr)
 
 static inline void ixgbe_write_reg64(struct ixgbe_hw *hw, u32 reg, u64 value)
 {
-	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
+	u8 __iomem *reg_addr = READ_ONCE(hw->hw_addr);
 
 	if (ixgbe_removed(reg_addr))
 		return;

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -380,7 +380,7 @@ static void ixgbe_check_remove(struct ixgbe_hw *hw, u32 reg)
  */
 u32 ixgbe_read_reg(struct ixgbe_hw *hw, u32 reg)
 {
-	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
+	u8 __iomem *reg_addr = READ_ONCE(hw->hw_addr);
 	u32 value;
 
 	if (ixgbe_removed(reg_addr))
@@ -8630,7 +8630,7 @@ static void ixgbe_get_stats64(struct net_device *netdev,
 
 	rcu_read_lock();
 	for (i = 0; i < adapter->num_rx_queues; i++) {
-		struct ixgbe_ring *ring = ACCESS_ONCE(adapter->rx_ring[i]);
+		struct ixgbe_ring *ring = READ_ONCE(adapter->rx_ring[i]);
 		u64 bytes, packets;
 		unsigned int start;
 
@@ -8646,12 +8646,12 @@ static void ixgbe_get_stats64(struct net_device *netdev,
 	}
 
 	for (i = 0; i < adapter->num_tx_queues; i++) {
-		struct ixgbe_ring *ring = ACCESS_ONCE(adapter->tx_ring[i]);
+		struct ixgbe_ring *ring = READ_ONCE(adapter->tx_ring[i]);
 
 		ixgbe_get_ring_stats64(stats, ring);
 	}
 	for (i = 0; i < adapter->num_xdp_queues; i++) {
-		struct ixgbe_ring *ring = ACCESS_ONCE(adapter->xdp_ring[i]);
+		struct ixgbe_ring *ring = READ_ONCE(adapter->xdp_ring[i]);
 
 		ixgbe_get_ring_stats64(stats, ring);
 	}

drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c

@@ -378,7 +378,7 @@ static int ixgbe_ptp_adjfreq_82599(struct ptp_clock_info *ptp, s32 ppb)
 	}
 
 	smp_mb();
-	incval = ACCESS_ONCE(adapter->base_incval);
+	incval = READ_ONCE(adapter->base_incval);
 
 	freq = incval;
 	freq *= ppb;
@@ -1159,7 +1159,7 @@ void ixgbe_ptp_start_cyclecounter(struct ixgbe_adapter *adapter)
 	}
 
 	/* update the base incval used to calculate frequency adjustment */
-	ACCESS_ONCE(adapter->base_incval) = incval;
+	WRITE_ONCE(adapter->base_incval, incval);
 	smp_mb();
 
 	/* need lock to prevent incorrect read while modifying cyclecounter */

drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c

@@ -164,7 +164,7 @@ static void ixgbevf_check_remove(struct ixgbe_hw *hw, u32 reg)
 
 u32 ixgbevf_read_reg(struct ixgbe_hw *hw, u32 reg)
 {
-	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
+	u8 __iomem *reg_addr = READ_ONCE(hw->hw_addr);
 	u32 value;
 
 	if (IXGBE_REMOVED(reg_addr))

drivers/net/ethernet/intel/ixgbevf/vf.h

@@ -182,7 +182,7 @@ struct ixgbevf_info {
 
 static inline void ixgbe_write_reg(struct ixgbe_hw *hw, u32 reg, u32 value)
 {
-	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
+	u8 __iomem *reg_addr = READ_ONCE(hw->hw_addr);
 
 	if (IXGBE_REMOVED(reg_addr))
 		return;