From: Michael S. Tsirkin <mst@redhat.com>
Date: Thu, 6 Jun 2019 21:17:36 +0000 (-0400)
Subject: vhost: fix clang build warning
X-Git-Tag: v5.3-rc1~57^2~9
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=0b4a7092ffe568a55bf8f3cefdf79ff666586d91;p=linux-block.git

vhost: fix clang build warning

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: 7f466032dc9e ("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>
---

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index c5d950cf7627..819296332913 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -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 {