Re: [PATCH] tools/virtio: fix build caused by virtio_ring changes

From: Shunsuke Mie
Date: Mon Apr 10 2023 - 06:56:21 EST



On 2023/04/10 19:00, Shunsuke Mie wrote:

On 2023/04/10 18:46, Michael S. Tsirkin wrote:
On Mon, Apr 10, 2023 at 06:24:19PM +0900, Shunsuke Mie wrote:
Fix the build dependency for virtio_test. virtio_ring requires
container_of_const() and struce device.

Signed-off-by: Shunsuke Mie <mie@xxxxxxxxxx>
---
  tools/include/linux/container_of.h | 36 ++++++++++++++++++++++++++++++
  tools/virtio/linux/compiler.h      |  3 +++
  tools/virtio/linux/kernel.h        |  5 +----
  tools/virtio/linux/module.h        |  1 +
  4 files changed, 41 insertions(+), 4 deletions(-)
  create mode 100644 tools/include/linux/container_of.h

diff --git a/tools/include/linux/container_of.h b/tools/include/linux/container_of.h
new file mode 100644
index 000000000000..06e293b7cfda
--- /dev/null
+++ b/tools/include/linux/container_of.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_CONTAINER_OF_H
+#define _LINUX_CONTAINER_OF_H
+
+#include <linux/build_bug.h>
+#include <linux/stddef.h>
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr:    the pointer to the member.
+ * @type:    the type of the container struct this is embedded in.
+ * @member:    the name of the member within the struct.
+ *
+ * WARNING: any const qualifier of @ptr is lost.
+ */
+#define container_of(ptr, type, member) ({                \
+    void *__mptr = (void *)(ptr);                    \
+    static_assert(__same_type(*(ptr), ((type *)0)->member) ||    \
+              __same_type(*(ptr), void),            \
+              "pointer type mismatch in container_of()"); \
+    ((type *)(__mptr - offsetof(type, member))); })
+
+/**
+ * container_of_const - cast a member of a structure out to the containing
+ *            structure and preserve the const-ness of the pointer
+ * @ptr:        the pointer to the member
+ * @type:        the type of the container struct this is embedded in.
+ * @member:        the name of the member within the struct.
+ */
+#define container_of_const(ptr, type, member) \
+    _Generic(ptr,                            \
+        const typeof(*(ptr)) *: ((const type *)container_of(ptr, type, member)),\
+        default: ((type *)container_of(ptr, type, member)) \
+    )
+
+#endif    /* _LINUX_CONTAINER_OF_H */

Please just do
#include "../../../include/linux/container_of.h"
instead.
Okey, I'll do that.


diff --git a/tools/virtio/linux/compiler.h b/tools/virtio/linux/compiler.h
index 2c51bccb97bb..ac27b3ea6e67 100644
--- a/tools/virtio/linux/compiler.h
+++ b/tools/virtio/linux/compiler.h
@@ -8,4 +8,7 @@
  #define READ_ONCE(var) (*((volatile typeof(var) *)(&(var))))
    #define __aligned(x) __attribute((__aligned__(x)))
+
+#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
+
  #endif
#include "../../../include/linux/compiler_types.h" instead?
I'll try it.
diff --git a/tools/virtio/linux/kernel.h b/tools/virtio/linux/kernel.h
index 8b877167933d..3cd20cb92649 100644
--- a/tools/virtio/linux/kernel.h
+++ b/tools/virtio/linux/kernel.h
@@ -10,6 +10,7 @@
  #include <stdarg.h>
    #include <linux/compiler.h>
+#include <linux/container_of.h>
  #include <linux/log2.h>
  #include <linux/types.h>
  #include <linux/overflow.h>
@@ -107,10 +108,6 @@ static inline void free_page(unsigned long addr)
      free((void *)addr);
  }
  -#define container_of(ptr, type, member) ({            \
-    const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
-    (type *)( (char *)__mptr - offsetof(type,member) );})
-
  # ifndef likely
  #  define likely(x)    (__builtin_expect(!!(x), 1))
  # endif
diff --git a/tools/virtio/linux/module.h b/tools/virtio/linux/module.h
index 9dfa96fea2b2..e2e791dbd104 100644
--- a/tools/virtio/linux/module.h
+++ b/tools/virtio/linux/module.h
@@ -5,3 +5,4 @@
      static __attribute__((unused)) const char *__MODULE_LICENSE_name = \
          __MODULE_LICENSE_value
  +struct device;

It's not there in include/linux/module - pls put it in the
same here where it is for linux.
I understood. I'll add some files that has the definition.

In vringh.c, 'struct device' is used in virtio_ring.h. Upon investigating the preprocessed file, it was

discovered that 'struct device' is defined in bitmap.h, which is included from architecture-specific headers.

On x86, the nesting includes

'linux/module.h' -> ... -> 'arch/x86/include/asm/msr.h' -> 'arch/x86/include/asm/cpumask.h' -> 'linux/cpumask.h' -> 'linux/bitmap.h'.

Could you advise on the appropriate way to include this file?

--
2.25.1

Best regards,

Shunsuke.