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/user_sdma.c b/drivers/infiniband/hw/hfi1/user_sdma.c
index c0c0e0445cbf..8ec6e8a8d6f7 100644
--- a/drivers/infiniband/hw/hfi1/user_sdma.c
+++ b/drivers/infiniband/hw/hfi1/user_sdma.c
@@ -276,7 +276,7 @@ int hfi1_user_sdma_free_queues(struct hfi1_filedata *fd,
 		/* Wait until all requests have been freed. */
 		wait_event_interruptible(
 			pq->wait,
-			(ACCESS_ONCE(pq->state) == SDMA_PKT_Q_INACTIVE));
+			(READ_ONCE(pq->state) == SDMA_PKT_Q_INACTIVE));
 		kfree(pq->reqs);
 		kfree(pq->req_in_use);
 		kmem_cache_destroy(pq->txreq_cache);
@@ -591,7 +591,7 @@ int hfi1_user_sdma_process_request(struct hfi1_filedata *fd,
 			if (ret != -EBUSY) {
 				req->status = ret;
 				WRITE_ONCE(req->has_error, 1);
-				if (ACCESS_ONCE(req->seqcomp) ==
+				if (READ_ONCE(req->seqcomp) ==
 				    req->seqsubmitted - 1)
 					goto free_req;
 				return ret;
@@ -825,7 +825,7 @@ static int user_sdma_send_pkts(struct user_sdma_request *req, unsigned maxpkts)
 		 */
 		if (req->data_len) {
 			iovec = &req->iovs[req->iov_idx];
-			if (ACCESS_ONCE(iovec->offset) == iovec->iov.iov_len) {
+			if (READ_ONCE(iovec->offset) == iovec->iov.iov_len) {
 				if (++req->iov_idx == req->data_iovs) {
 					ret = -EFAULT;
 					goto free_txreq;
@@ -1390,7 +1390,7 @@ static void user_sdma_txreq_cb(struct sdma_txreq *txreq, int status)
 	} else {
 		if (status != SDMA_TXREQ_S_OK)
 			req->status = status;
-		if (req->seqcomp == (ACCESS_ONCE(req->seqsubmitted) - 1) &&
+		if (req->seqcomp == (READ_ONCE(req->seqsubmitted) - 1) &&
 		    (READ_ONCE(req->done) ||
 		     READ_ONCE(req->has_error))) {
 			user_sdma_free_request(req, false);