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authorMark Rutland <mark.rutland@arm.com>2017-10-23 23:07:29 +0200
committerIngo Molnar <mingo@kernel.org>2017-10-25 11:01:08 +0200
commit6aa7de059173a986114ac43b8f50b297a86f09a8 (patch)
tree77666afe795e022914ca26433d61686c694dc4fd /drivers/usb/host
parentlocking/atomics, mm: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_ONCE() (diff)
downloadlinux-6aa7de059173a986114ac43b8f50b297a86f09a8.tar.xz
linux-6aa7de059173a986114ac43b8f50b297a86f09a8.zip
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>
Diffstat (limited to 'drivers/usb/host')
-rw-r--r--drivers/usb/host/ohci-hcd.c2
-rw-r--r--drivers/usb/host/uhci-hcd.h4
2 files changed, 3 insertions, 3 deletions
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))