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

[Shunsuke Mie]

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.