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>

5 files changed, 14 insertions, 14 deletions

diff --git a/drivers/net/ethernet/sfc/falcon/efx.c b/drivers/net/ethernet/sfc/falcon/efx.c
index 29614da91cbf..7263275fde4a 100644
--- a/drivers/net/ethernet/sfc/falcon/efx.c
+++ b/drivers/net/ethernet/sfc/falcon/efx.c
@@ -2545,7 +2545,7 @@ static void ef4_reset_work(struct work_struct *data)
 	unsigned long pending;
 	enum reset_type method;
 
-	pending = ACCESS_ONCE(efx->reset_pending);
+	pending = READ_ONCE(efx->reset_pending);
 	method = fls(pending) - 1;
 
 	if ((method == RESET_TYPE_RECOVER_OR_DISABLE ||
@@ -2605,7 +2605,7 @@ void ef4_schedule_reset(struct ef4_nic *efx, enum reset_type type)
 	/* If we're not READY then just leave the flags set as the cue
 	 * to abort probing or reschedule the reset later.
 	 */
-	if (ACCESS_ONCE(efx->state) != STATE_READY)
+	if (READ_ONCE(efx->state) != STATE_READY)
 		return;
 
 	queue_work(reset_workqueue, &efx->reset_work);
diff --git a/drivers/net/ethernet/sfc/falcon/falcon.c b/drivers/net/ethernet/sfc/falcon/falcon.c
index 93c713c1f627..cd8bb472d758 100644
--- a/drivers/net/ethernet/sfc/falcon/falcon.c
+++ b/drivers/net/ethernet/sfc/falcon/falcon.c
@@ -452,7 +452,7 @@ static irqreturn_t falcon_legacy_interrupt_a1(int irq, void *dev_id)
 		   "IRQ %d on CPU %d status " EF4_OWORD_FMT "\n",
 		   irq, raw_smp_processor_id(), EF4_OWORD_VAL(*int_ker));
 
-	if (!likely(ACCESS_ONCE(efx->irq_soft_enabled)))
+	if (!likely(READ_ONCE(efx->irq_soft_enabled)))
 		return IRQ_HANDLED;
 
 	/* Check to see if we have a serious error condition */
@@ -1372,7 +1372,7 @@ static void falcon_reconfigure_mac_wrapper(struct ef4_nic *efx)
 	ef4_oword_t reg;
 	int link_speed, isolate;
 
-	isolate = !!ACCESS_ONCE(efx->reset_pending);
+	isolate = !!READ_ONCE(efx->reset_pending);
 
 	switch (link_state->speed) {
 	case 10000: link_speed = 3; break;
diff --git a/drivers/net/ethernet/sfc/falcon/farch.c b/drivers/net/ethernet/sfc/falcon/farch.c
index 05916c710d8c..494884f6af4a 100644
--- a/drivers/net/ethernet/sfc/falcon/farch.c
+++ b/drivers/net/ethernet/sfc/falcon/farch.c
@@ -834,7 +834,7 @@ ef4_farch_handle_tx_event(struct ef4_channel *channel, ef4_qword_t *event)
 	struct ef4_nic *efx = channel->efx;
 	int tx_packets = 0;
 
-	if (unlikely(ACCESS_ONCE(efx->reset_pending)))
+	if (unlikely(READ_ONCE(efx->reset_pending)))
 		return 0;
 
 	if (likely(EF4_QWORD_FIELD(*event, FSF_AZ_TX_EV_COMP))) {
@@ -990,7 +990,7 @@ ef4_farch_handle_rx_event(struct ef4_channel *channel, const ef4_qword_t *event)
 	struct ef4_rx_queue *rx_queue;
 	struct ef4_nic *efx = channel->efx;
 
-	if (unlikely(ACCESS_ONCE(efx->reset_pending)))
+	if (unlikely(READ_ONCE(efx->reset_pending)))
 		return;
 
 	rx_ev_cont = EF4_QWORD_FIELD(*event, FSF_AZ_RX_EV_JUMBO_CONT);
@@ -1504,7 +1504,7 @@ irqreturn_t ef4_farch_fatal_interrupt(struct ef4_nic *efx)
 irqreturn_t ef4_farch_legacy_interrupt(int irq, void *dev_id)
 {
 	struct ef4_nic *efx = dev_id;
-	bool soft_enabled = ACCESS_ONCE(efx->irq_soft_enabled);
+	bool soft_enabled = READ_ONCE(efx->irq_soft_enabled);
 	ef4_oword_t *int_ker = efx->irq_status.addr;
 	irqreturn_t result = IRQ_NONE;
 	struct ef4_channel *channel;
@@ -1596,7 +1596,7 @@ irqreturn_t ef4_farch_msi_interrupt(int irq, void *dev_id)
 		   "IRQ %d on CPU %d status " EF4_OWORD_FMT "\n",
 		   irq, raw_smp_processor_id(), EF4_OWORD_VAL(*int_ker));
 
-	if (!likely(ACCESS_ONCE(efx->irq_soft_enabled)))
+	if (!likely(READ_ONCE(efx->irq_soft_enabled)))
 		return IRQ_HANDLED;
 
 	/* Handle non-event-queue sources */
diff --git a/drivers/net/ethernet/sfc/falcon/nic.h b/drivers/net/ethernet/sfc/falcon/nic.h
index a4c4592f6023..54ca457cdb15 100644
--- a/drivers/net/ethernet/sfc/falcon/nic.h
+++ b/drivers/net/ethernet/sfc/falcon/nic.h
@@ -83,7 +83,7 @@ static inline struct ef4_tx_queue *ef4_tx_queue_partner(struct ef4_tx_queue *tx_
 static inline bool __ef4_nic_tx_is_empty(struct ef4_tx_queue *tx_queue,
 					 unsigned int write_count)
 {
-	unsigned int empty_read_count = ACCESS_ONCE(tx_queue->empty_read_count);
+	unsigned int empty_read_count = READ_ONCE(tx_queue->empty_read_count);
 
 	if (empty_read_count == 0)
 		return false;
@@ -464,11 +464,11 @@ irqreturn_t ef4_farch_fatal_interrupt(struct ef4_nic *efx);
 
 static inline int ef4_nic_event_test_irq_cpu(struct ef4_channel *channel)
 {
-	return ACCESS_ONCE(channel->event_test_cpu);
+	return READ_ONCE(channel->event_test_cpu);
 }
 static inline int ef4_nic_irq_test_irq_cpu(struct ef4_nic *efx)
 {
-	return ACCESS_ONCE(efx->last_irq_cpu);
+	return READ_ONCE(efx->last_irq_cpu);
 }
 
 /* Global Resources */
diff --git a/drivers/net/ethernet/sfc/falcon/tx.c b/drivers/net/ethernet/sfc/falcon/tx.c
index 6a75f4140a4b..6486814e97dc 100644
--- a/drivers/net/ethernet/sfc/falcon/tx.c
+++ b/drivers/net/ethernet/sfc/falcon/tx.c
@@ -134,8 +134,8 @@ static void ef4_tx_maybe_stop_queue(struct ef4_tx_queue *txq1)
 	 */
 	netif_tx_stop_queue(txq1->core_txq);
 	smp_mb();
-	txq1->old_read_count = ACCESS_ONCE(txq1->read_count);
-	txq2->old_read_count = ACCESS_ONCE(txq2->read_count);
+	txq1->old_read_count = READ_ONCE(txq1->read_count);
+	txq2->old_read_count = READ_ONCE(txq2->read_count);
 
 	fill_level = max(txq1->insert_count - txq1->old_read_count,
 			 txq2->insert_count - txq2->old_read_count);
@@ -524,7 +524,7 @@ void ef4_xmit_done(struct ef4_tx_queue *tx_queue, unsigned int index)
 
 	/* Check whether the hardware queue is now empty */
 	if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
-		tx_queue->old_write_count = ACCESS_ONCE(tx_queue->write_count);
+		tx_queue->old_write_count = READ_ONCE(tx_queue->write_count);
 		if (tx_queue->read_count == tx_queue->old_write_count) {
 			smp_mb();
 			tx_queue->empty_read_count =