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>

2 files changed, 3 insertions, 3 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 12ebd055724c..4b8ba2a75a4d 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -668,7 +668,7 @@ const char *dev_driver_string(const struct device *dev)
 	 * so be careful about accessing it.  dev->bus and dev->class should
 	 * never change once they are set, so they don't need special care.
 	 */
-	drv = ACCESS_ONCE(dev->driver);
+	drv = READ_ONCE(dev->driver);
 	return drv ? drv->name :
 			(dev->bus ? dev->bus->name :
 			(dev->class ? dev->class->name : ""));
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 7bcf80fa9ada..41d7c2b99f69 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -134,11 +134,11 @@ unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
 	if (!dev->power.use_autosuspend)
 		goto out;
 
-	autosuspend_delay = ACCESS_ONCE(dev->power.autosuspend_delay);
+	autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 	if (autosuspend_delay < 0)
 		goto out;
 
-	last_busy = ACCESS_ONCE(dev->power.last_busy);
+	last_busy = READ_ONCE(dev->power.last_busy);
 	elapsed = jiffies - last_busy;
 	if (elapsed < 0)
 		goto out;	/* jiffies has wrapped around. */