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    Subject[PATCH 3/3] tools/virtio: use {READ,WRITE}_ONCE() in uaccess.h
    Date
    As a step towards killing off ACCESS_ONCE, use {READ,WRITE}_ONCE() for the
    virtio tools uaccess primitives, pulling these in from <linux/compiler.h>.

    With this done, we can kill off the now-unused ACCESS_ONCE() definition.

    Signed-off-by: Mark Rutland <mark.rutland@arm.com>
    Cc: Jason Wang <jasowang@redhat.com>
    Cc: Michael S. Tsirkin <mst@redhat.com>
    Cc: linux-kernel@vger.kernel.org
    Cc: virtualization@lists.linux-foundation.org
    ---
    tools/virtio/linux/uaccess.h | 9 +++++----
    1 file changed, 5 insertions(+), 4 deletions(-)

    diff --git a/tools/virtio/linux/uaccess.h b/tools/virtio/linux/uaccess.h
    index 0a578fe..fa05d01 100644
    --- a/tools/virtio/linux/uaccess.h
    +++ b/tools/virtio/linux/uaccess.h
    @@ -1,8 +1,9 @@
    #ifndef UACCESS_H
    #define UACCESS_H
    -extern void *__user_addr_min, *__user_addr_max;

    -#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
    +#include <linux/compiler.h>
    +
    +extern void *__user_addr_min, *__user_addr_max;

    static inline void __chk_user_ptr(const volatile void *p, size_t size)
    {
    @@ -13,7 +14,7 @@ static inline void __chk_user_ptr(const volatile void *p, size_t size)
    ({ \
    typeof(ptr) __pu_ptr = (ptr); \
    __chk_user_ptr(__pu_ptr, sizeof(*__pu_ptr)); \
    - ACCESS_ONCE(*(__pu_ptr)) = x; \
    + WRITE_ONCE(*(__pu_ptr), x); \
    0; \
    })

    @@ -21,7 +22,7 @@ static inline void __chk_user_ptr(const volatile void *p, size_t size)
    ({ \
    typeof(ptr) __pu_ptr = (ptr); \
    __chk_user_ptr(__pu_ptr, sizeof(*__pu_ptr)); \
    - x = ACCESS_ONCE(*(__pu_ptr)); \
    + x = READ_ONCE(*(__pu_ptr)); \
    0; \
    })

    --
    2.7.4
    \
     
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