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>

3 files changed, 4 insertions, 4 deletions

diff --git a/arch/tile/gxio/dma_queue.c b/arch/tile/gxio/dma_queue.c
index baa60357f8ba..b7ba577d82ca 100644
--- a/arch/tile/gxio/dma_queue.c
+++ b/arch/tile/gxio/dma_queue.c
@@ -163,14 +163,14 @@ int __gxio_dma_queue_is_complete(__gxio_dma_queue_t *dma_queue,
 				 int64_t completion_slot, int update)
 {
 	if (update) {
-		if (ACCESS_ONCE(dma_queue->hw_complete_count) >
+		if (READ_ONCE(dma_queue->hw_complete_count) >
 		    completion_slot)
 			return 1;
 
 		__gxio_dma_queue_update_credits(dma_queue);
 	}
 
-	return ACCESS_ONCE(dma_queue->hw_complete_count) > completion_slot;
+	return READ_ONCE(dma_queue->hw_complete_count) > completion_slot;
 }
 
 EXPORT_SYMBOL_GPL(__gxio_dma_queue_is_complete);
diff --git a/arch/tile/include/gxio/dma_queue.h b/arch/tile/include/gxio/dma_queue.h
index b9e45e37649e..c8fd47edba30 100644
--- a/arch/tile/include/gxio/dma_queue.h
+++ b/arch/tile/include/gxio/dma_queue.h
@@ -121,7 +121,7 @@ static inline int64_t __gxio_dma_queue_reserve(__gxio_dma_queue_t *dma_queue,
 		 * if the result is LESS than "hw_complete_count".
 		 */
 		uint64_t complete;
-		complete = ACCESS_ONCE(dma_queue->hw_complete_count);
+		complete = READ_ONCE(dma_queue->hw_complete_count);
 		slot |= (complete & 0xffffffffff000000);
 		if (slot < complete)
 			slot += 0x1000000;
diff --git a/arch/tile/kernel/ptrace.c b/arch/tile/kernel/ptrace.c
index e1a078e6828e..d516d61751c2 100644
--- a/arch/tile/kernel/ptrace.c
+++ b/arch/tile/kernel/ptrace.c
@@ -255,7 +255,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 
 int do_syscall_trace_enter(struct pt_regs *regs)
 {
-	u32 work = ACCESS_ONCE(current_thread_info()->flags);
+	u32 work = READ_ONCE(current_thread_info()->flags);
 
 	if ((work & _TIF_SYSCALL_TRACE) &&
 	    tracehook_report_syscall_entry(regs)) {