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/infiniband/hw/hfi1/sdma.c b/drivers/infiniband/hw/hfi1/sdma.c
index 6781bcdb10b3..08346d25441c 100644
--- a/drivers/infiniband/hw/hfi1/sdma.c
+++ b/drivers/infiniband/hw/hfi1/sdma.c
@@ -1725,7 +1725,7 @@ retry:
 
 		swhead = sde->descq_head & sde->sdma_mask;
 		/* this code is really bad for cache line trading */
-		swtail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask;
+		swtail = READ_ONCE(sde->descq_tail) & sde->sdma_mask;
 		cnt = sde->descq_cnt;
 
 		if (swhead < swtail)
@@ -1872,7 +1872,7 @@ retry:
 	if ((status & sde->idle_mask) && !idle_check_done) {
 		u16 swtail;
 
-		swtail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask;
+		swtail = READ_ONCE(sde->descq_tail) & sde->sdma_mask;
 		if (swtail != hwhead) {
 			hwhead = (u16)read_sde_csr(sde, SD(HEAD));
 			idle_check_done = 1;
@@ -2222,7 +2222,7 @@ void sdma_seqfile_dump_sde(struct seq_file *s, struct sdma_engine *sde)
 	u16 len;
 
 	head = sde->descq_head & sde->sdma_mask;
-	tail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask;
+	tail = READ_ONCE(sde->descq_tail) & sde->sdma_mask;
 	seq_printf(s, SDE_FMT, sde->this_idx,
 		   sde->cpu,
 		   sdma_state_name(sde->state.current_state),
@@ -3305,7 +3305,7 @@ int sdma_ahg_alloc(struct sdma_engine *sde)
 		return -EINVAL;
 	}
 	while (1) {
-		nr = ffz(ACCESS_ONCE(sde->ahg_bits));
+		nr = ffz(READ_ONCE(sde->ahg_bits));
 		if (nr > 31) {
 			trace_hfi1_ahg_allocate(sde, -ENOSPC);
 			return -ENOSPC;