From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH RESEND] virtio: Fix typecast of pointer in vring_init() Date: Sun, 5 Jul 2015 12:58:53 +0200 Message-ID: <20150705124937-mutt-send-email-mst@redhat.com> References: <1435821682-1809-1-git-send-email-thuth@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1435821682-1809-1-git-send-email-thuth-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thomas Huth Cc: virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Thu, Jul 02, 2015 at 09:21:22AM +0200, Thomas Huth wrote: > The virtio_ring.h header is used in userspace programs (ie. QEMU), > too. Here we can not assume that sizeof(pointer) is the same as > sizeof(long), e.g. when compiling for Windows, so the typecast in > vring_init() should be done with (uintptr_t) instead of (unsigned lon= g). >=20 > Signed-off-by: Thomas Huth This seems to break some userspace too: INSTALL usr/include/linux/ (413 files) CHECK usr/include/linux/ (413 files) HOSTCC Documentation/accounting/getdelays HOSTCC Documentation/connector/ucon HOSTCC Documentation/mic/mpssd/mpssd.o In file included from Documentation/mic/mpssd/mpssd.c:36:0: =2E/usr/include/linux/virtio_ring.h: In function =E2=80=98vring_init=E2= =80=99: =2E/usr/include/linux/virtio_ring.h:146:24: error: =E2=80=98uintptr_t=E2= =80=99 undeclared (first use in this function) vr->used =3D (void *)(((uintptr_t)&vr->avail->ring[num] + sizeof(__virtio16) ^ =2E/usr/include/linux/virtio_ring.h:146:24: note: each undeclared identifier is reported only once for each function it appears in scripts/Makefile.host:108: recipe for target 'Documentation/mic/mpssd/mpssd.o' failed make[3]: *** [Documentation/mic/mpssd/mpssd.o] Error 1 scripts/Makefile.build:403: recipe for target 'Documentation/mic/mpssd' failed make[2]: *** [Documentation/mic/mpssd] Error 2 scripts/Makefile.build:403: recipe for target 'Documentation/mic' faile= d make[1]: *** [Documentation/mic] Error 2 E.g. fuse.h has this code: #ifdef __KERNEL__ #include #else #include #endif Maybe we need something similar. > --- > include/uapi/linux/virtio_ring.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/vi= rtio_ring.h > index 915980a..8682551 100644 > --- a/include/uapi/linux/virtio_ring.h > +++ b/include/uapi/linux/virtio_ring.h > @@ -143,7 +143,7 @@ static inline void vring_init(struct vring *vr, u= nsigned int num, void *p, > vr->num =3D num; > vr->desc =3D p; > vr->avail =3D p + num*sizeof(struct vring_desc); > - vr->used =3D (void *)(((unsigned long)&vr->avail->ring[num] + sizeo= f(__virtio16) > + vr->used =3D (void *)(((uintptr_t)&vr->avail->ring[num] + sizeof(__= virtio16) > + align-1) & ~(align - 1)); > } > =20 > --=20 > 1.8.3.1