[Qemu-devel] Re: [PATCH] fix ioctl return value

[Anthony Liguori <aliguori@us.ibm.com>]

Glauber Costa wrote:
> we expect a number less than 0, not exactly -1.
> And furthermore, we return errno itself, so no need to use it.
>
> This might break guests when this ioctl fails for some reason.
>
> Signed-off-by: Glauber Costa <glommer@redhat.com>
> ---
>  kvm-all.c |    5 ++---
>  1 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/kvm-all.c b/kvm-all.c
> index 8567ac9..9a79466 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -319,9 +319,8 @@ int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
>
>          d.slot = mem->slot;
>
> -        if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
> -            dprintf("ioctl failed %d\n", errno);
> -            ret = -1;
> +        if ((ret = kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d)) < 0) {
> +            dprintf("ioctl failed %d\n", ret);
>   

While this is fine, I usually prefer:

ret = kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d);
if (ret < 0) {
    dprintf(ioctl failed %d\n", ret);

-- 
Regards,

Anthony Liguori