Messages in this thread | | | From | Matej Genci <> | Subject | Re: [PATCH] virtio: Change typecasts in vring_init() | Date | Fri, 30 Aug 2019 17:58:23 +0000 |
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On 8/30/2019 3:02 PM, Michael S. Tsirkin wrote: > On Tue, Aug 27, 2019 at 03:20:57PM +0000, Matej Genci wrote: >> Compilers such as g++ 7.3 complain about assigning void* variable to >> a non-void* variable (like struct pointers) and pointer arithmetics >> on void*. >> >> Signed-off-by: Matej Genci <matej.genci@nutanix.com> >> --- >> include/uapi/linux/virtio_ring.h | 9 +++++---- >> 1 file changed, 5 insertions(+), 4 deletions(-) >> >> diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h >> index 4c4e24c291a5..2c339b9e2923 100644 >> --- a/include/uapi/linux/virtio_ring.h >> +++ b/include/uapi/linux/virtio_ring.h >> @@ -168,10 +168,11 @@ static inline void vring_init(struct vring *vr, unsigned int num, void *p, >> unsigned long align) >> { >> vr->num = num; >> - vr->desc = p; >> - vr->avail = p + num*sizeof(struct vring_desc); >> - vr->used = (void *)(((uintptr_t)&vr->avail->ring[num] + sizeof(__virtio16) >> - + align-1) & ~(align - 1)); >> + vr->desc = (struct vring_desc *)p; >> + vr->avail = (struct vring_avail *)((uintptr_t)p >> + + num*sizeof(struct vring_desc)); >> + vr->used = (struct vring_used *)(((uintptr_t)&vr->avail->ring[num] >> + + sizeof(__virtio16) + align-1) & ~(align - 1)); >> } >> >> static inline unsigned vring_size(unsigned int num, unsigned long align) > > I'm not really interested in building with g++, sorry. > Centainly not if it makes code less robust by forcing > casts where they weren't previously necessary.
Can you elaborate on how these casts make the code less robust? They aren't necessary in C but I think being explicit can improve readability as argued in https://softwareengineering.stackexchange.com/a/275714
> > However, vring_init and vring_size are legacy APIs anyway, > so I'd be happy to add ifndefs that will allow userspace > simply hide these functions if it does not need them. >
I feel like my patch is a harmless way of allowing this header to be used in C++ projects, but I'm happy to drop it in lieu of the guards if you feel strongly about it.
Thanks. Matej
> >> -- >> 2.22.0 >>
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