From: Alan Stern Date: Wed, 18 May 2011 08:44:50 +0000 (+0200) Subject: USB: UHCI: Use ACCESS_ONCE rather than using a full compiler barrier X-Git-Tag: v3.0-rc1~337^2~4 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=bab1ff1bda27e654dfd382a1fbdfcda1f7ed0a37;p=linux.git 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 Signed-off-by: Greg Kroah-Hartman --- 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))