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>

6 files changed, 9 insertions, 9 deletions

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 3e865dbf878c..fbaa2a90d25d 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -483,7 +483,7 @@ static ssize_t wdm_read
 	if (rv < 0)
 		return -ERESTARTSYS;
 
-	cntr = ACCESS_ONCE(desc->length);
+	cntr = READ_ONCE(desc->length);
 	if (cntr == 0) {
 		desc->read = 0;
 retry:
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index e9326f31db8d..4ae667d8c238 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -150,7 +150,7 @@ static int usbfs_increase_memory_usage(u64 amount)
 {
 	u64 lim;
 
-	lim = ACCESS_ONCE(usbfs_memory_mb);
+	lim = READ_ONCE(usbfs_memory_mb);
 	lim <<= 20;
 
 	atomic64_add(amount, &usbfs_memory_usage);
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index d930bfda4010..58d59c5f8592 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -973,7 +973,7 @@ static ssize_t interface_show(struct device *dev, struct device_attribute *attr,
 	char *string;
 
 	intf = to_usb_interface(dev);
-	string = ACCESS_ONCE(intf->cur_altsetting->string);
+	string = READ_ONCE(intf->cur_altsetting->string);
 	if (!string)
 		return 0;
 	return sprintf(buf, "%s\n", string);
@@ -989,7 +989,7 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 
 	intf = to_usb_interface(dev);
 	udev = interface_to_usbdev(intf);
-	alt = ACCESS_ONCE(intf->cur_altsetting);
+	alt = READ_ONCE(intf->cur_altsetting);
 
 	return sprintf(buf, "usb:v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02X"
 			"ic%02Xisc%02Xip%02Xin%02X\n",
diff --git a/drivers/usb/gadget/udc/gr_udc.c b/drivers/usb/gadget/udc/gr_udc.c
index 1f9941145746..0b59fa50aa30 100644
--- a/drivers/usb/gadget/udc/gr_udc.c
+++ b/drivers/usb/gadget/udc/gr_udc.c
@@ -1261,7 +1261,7 @@ static int gr_handle_in_ep(struct gr_ep *ep)
 	if (!req->last_desc)
 		return 0;
 
-	if (ACCESS_ONCE(req->last_desc->ctrl) & GR_DESC_IN_CTRL_EN)
+	if (READ_ONCE(req->last_desc->ctrl) & GR_DESC_IN_CTRL_EN)
 		return 0; /* Not put in hardware buffers yet */
 
 	if (gr_read32(&ep->regs->epstat) & (GR_EPSTAT_B1 | GR_EPSTAT_B0))
@@ -1290,7 +1290,7 @@ static int gr_handle_out_ep(struct gr_ep *ep)
 	if (!req->curr_desc)
 		return 0;
 
-	ctrl = ACCESS_ONCE(req->curr_desc->ctrl);
+	ctrl = READ_ONCE(req->curr_desc->ctrl);
 	if (ctrl & GR_DESC_OUT_CTRL_EN)
 		return 0; /* Not received yet */
 
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 44924824fa41..c86f89babd57 100644
--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -785,7 +785,7 @@ static void io_watchdog_func(unsigned long _ohci)
 		}
 
 		/* find the last TD processed by the controller. */
-		head = hc32_to_cpu(ohci, ACCESS_ONCE(ed->hwHeadP)) & TD_MASK;
+		head = hc32_to_cpu(ohci, READ_ONCE(ed->hwHeadP)) & TD_MASK;
 		td_start = td;
 		td_next = list_prepare_entry(td, &ed->td_list, td_list);
 		list_for_each_entry_continue(td_next, &ed->td_list, td_list) {
diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
index 91b22b2ea3aa..09a2a259941b 100644
--- a/drivers/usb/host/uhci-hcd.h
+++ b/drivers/usb/host/uhci-hcd.h
@@ -186,7 +186,7 @@ struct uhci_qh {
  * We need a special accessor for the element pointer because it is
  * subject to asynchronous updates by the controller.
  */
-#define qh_element(qh)		ACCESS_ONCE((qh)->element)
+#define qh_element(qh)		READ_ONCE((qh)->element)
 
 #define LINK_TO_QH(uhci, qh)	(UHCI_PTR_QH((uhci)) | \
 				cpu_to_hc32((uhci), (qh)->dma_handle))
@@ -274,7 +274,7 @@ struct uhci_td {
  * subject to asynchronous updates by the controller.
  */
 #define td_status(uhci, td)		hc32_to_cpu((uhci), \
-						ACCESS_ONCE((td)->status))
+						READ_ONCE((td)->status))
 
 #define LINK_TO_TD(uhci, td)		(cpu_to_hc32((uhci), (td)->dma_handle))