This patch (as1462) updates the special accessor functions defined in
uhci-hcd.h. Rather than using a full compiler barrier, all we really
need is the ACCESS_ONCE() mechanism, because the idea is to prevent
the compiler from caching a value that can change at any time.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
Update for V2 of patch series:
Added this patch from Alan Stern.
---
drivers/usb/host/uhci-hcd.h | 14 ++------------
1 files changed, 2 insertions(+), 12 deletions(-)
diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
index 31f110f..20a8949 100644
--- a/drivers/usb/host/uhci-hcd.h
+++ b/drivers/usb/host/uhci-hcd.h
@@ -168,12 +168,7 @@ struct uhci_qh {
* We need a special accessor for the element pointer because it is
* subject to asynchronous updates by the controller.
*/
-static inline __le32 qh_element(struct uhci_qh *qh) {
- __le32 element = qh->element;
-
- barrier();
- return element;
-}
+#define qh_element(qh) ACCESS_ONCE((qh)->element)
#define LINK_TO_QH(qh) (UHCI_PTR_QH | cpu_to_le32((qh)->dma_handle))
@@ -263,12 +258,7 @@ struct uhci_td {
* We need a special accessor for the control/status word because it is
* subject to asynchronous updates by the controller.
*/
-static inline u32 td_status(struct uhci_td *td) {
- __le32 status = td->status;
-
- barrier();
- return le32_to_cpu(status);
-}
+#define td_status(td) le32_to_cpu(ACCESS_ONCE((td)->status))
#define LINK_TO_TD(td) (cpu_to_le32((td)->dma_handle))
--
1.7.0.4
--
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