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>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 4d76afd13868..2224e691ee07 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/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);
 	}