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| author | Alan Stern <stern@rowland.harvard.edu> | 2011-05-18 10:44:50 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-05-19 16:43:19 -0700 |
| commit | bab1ff1bda27e654dfd382a1fbdfcda1f7ed0a37 (patch) | |
| tree | 9ff9d83fa7f81eecd5569c0bd9089ea39da3880a /drivers/usb | |
| parent | 8452c6745e74384e7e434144f989ada3eae41170 (diff) | |
| download | linux-bab1ff1bda27e654dfd382a1fbdfcda1f7ed0a37.tar.bz2 | |
USB: UHCI: Use ACCESS_ONCE rather than using a full compiler barrier
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 force the
compiler to store a fixed copy of a possibly changing value.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | 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 10b68a846f65..0deeab6c9e56 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)) |