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, 5 insertions, 5 deletions

diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 60cdb97f58e2..56c2db398def 100644
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -658,7 +658,7 @@ static void efx_ptp_send_times(struct efx_nic *efx,
 
 	/* Write host time for specified period or until MC is done */
 	while ((timespec64_compare(&now.ts_real, &limit) < 0) &&
-	       ACCESS_ONCE(*mc_running)) {
+	       READ_ONCE(*mc_running)) {
 		struct timespec64 update_time;
 		unsigned int host_time;
 
@@ -668,7 +668,7 @@ static void efx_ptp_send_times(struct efx_nic *efx,
 		do {
 			pps_get_ts(&now);
 		} while ((timespec64_compare(&now.ts_real, &update_time) < 0) &&
-			 ACCESS_ONCE(*mc_running));
+			 READ_ONCE(*mc_running));
 
 		/* Synchronise NIC with single word of time only */
 		host_time = (now.ts_real.tv_sec << MC_NANOSECOND_BITS |
@@ -832,14 +832,14 @@ static int efx_ptp_synchronize(struct efx_nic *efx, unsigned int num_readings)
 		       ptp->start.dma_addr);
 
 	/* Clear flag that signals MC ready */
-	ACCESS_ONCE(*start) = 0;
+	WRITE_ONCE(*start, 0);
 	rc = efx_mcdi_rpc_start(efx, MC_CMD_PTP, synch_buf,
 				MC_CMD_PTP_IN_SYNCHRONIZE_LEN);
 	EFX_WARN_ON_ONCE_PARANOID(rc);
 
 	/* Wait for start from MCDI (or timeout) */
 	timeout = jiffies + msecs_to_jiffies(MAX_SYNCHRONISE_WAIT_MS);
-	while (!ACCESS_ONCE(*start) && (time_before(jiffies, timeout))) {
+	while (!READ_ONCE(*start) && (time_before(jiffies, timeout))) {
 		udelay(20);	/* Usually start MCDI execution quickly */
 		loops++;
 	}
@@ -849,7 +849,7 @@ static int efx_ptp_synchronize(struct efx_nic *efx, unsigned int num_readings)
 	if (!time_before(jiffies, timeout))
 		++ptp->sync_timeouts;
 
-	if (ACCESS_ONCE(*start))
+	if (READ_ONCE(*start))
 		efx_ptp_send_times(efx, &last_time);
 
 	/* Collect results */