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vhost: fix clang build warning

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Clang warns:

  drivers/vhost/vhost.c:2085:5: warning: macro expansion producing
  'defined' has undefined behavior [-Wexpansion-to-defined]
  #if VHOST_ARCH_CAN_ACCEL_UACCESS
      ^
  drivers/vhost/vhost.h:98:38: note: expanded from macro
  'VHOST_ARCH_CAN_ACCEL_UACCESS'
  #define VHOST_ARCH_CAN_ACCEL_UACCESS defined(CONFIG_MMU_NOTIFIER) && \
                                       ^

It's being pedantic for the sake of portability, but the fix is easy
enough.

Rework the definition of VHOST_ARCH_CAN_ACCEL_UACCESS to expand to a constant.

Fixes: 7f466032dc ("vhost: access vq metadata through kernel virtual address")
Link: https://github.com/ClangBuiltLinux/linux/issues/508
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
This commit is contained in:
Michael S. Tsirkin 2019-06-06 17:17:36 -04:00
parent 7f466032dc
commit 0b4a7092ff
1 changed files with 5 additions and 2 deletions
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7
drivers/vhost/vhost.h
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@ -95,8 +95,11 @@ struct vhost_uaddr {
bool write;
};
#define VHOST_ARCH_CAN_ACCEL_UACCESS defined(CONFIG_MMU_NOTIFIER) && \
ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0
#if defined(CONFIG_MMU_NOTIFIER) && ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0
#define VHOST_ARCH_CAN_ACCEL_UACCESS 1
#else
#define VHOST_ARCH_CAN_ACCEL_UACCESS 0
#endif
/* The virtqueue structure describes a queue attached to a device. */
struct vhost_virtqueue {