lkml.org 
[lkml]   [2016]   [Feb]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: drivers/vhost/vhost.c:718:3: error: call to '__compiletime_assert_718' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE
On Sun, Feb 28, 2016 at 07:15:14AM +0800, kbuild test robot wrote:
> Hi Michael,
>
> FYI, the error/warning still remains.
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 691429e13dfaf5b0994b07cc166db41bd608ee3d
> commit: 5d9a07b0de512b77bf28d2401e5fe3351f00a240 vhost: relax used address alignment
> date: 1 year, 2 months ago
> config: openrisc-allmodconfig (attached as .config)
> reproduce:
> wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> git checkout 5d9a07b0de512b77bf28d2401e5fe3351f00a240
> # save the attached .config to linux build tree
> make.cross ARCH=openrisc
>
> All errors (new ones prefixed by >>):
>
> drivers/vhost/vhost.c: In function 'vhost_vring_ioctl':
> >> drivers/vhost/vhost.c:718:3: error: call to '__compiletime_assert_718' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE
>
> vim +/__compiletime_assert_718 +718 drivers/vhost/vhost.c
>
> 712 (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
> 713 r = -EFAULT;
> 714 break;
> 715 }
> 716
> 717 /* Make sure it's safe to cast pointers to vring types. */
> > 718 BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
> 719 BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
> 720 if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
> 721 (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation

I still think it's a bug in the openrisc compiler used.

struct vring_avail {
unsigned short flags;
unsigned short idx;
};

struct vring_avail *x;

int main(int argc, char **argv)
{

footest();
if (__alignof__(*x) == 1)
foo1();
else if (__alignof__(*x) == 2)
foo2();
else if (__alignof__(*x) == 4)
foo4();
else if (__alignof__(*x) == 8)
foo8();
else
fooother();
return 0;
}

when compiled with the openrisc compiler from kernel.org this calls foo4
and it really should call foo2, since the openrisc manual says:

16.1.2
Aggregates and Unions
Aggregates (structures and arrays) and unions assume the alignment of
their most
strictly aligned element.

and alignment for unsigned short is 2.



--
MST

\
 
 \ /
  Last update: 2016-02-28 10:41    [W:0.068 / U:0.312 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site