Messages in this thread | | | Date | Mon, 12 Mar 2007 06:40:18 +0100 (MET) | From | Jan Engelhardt <> | Subject | Re: Style Question |
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On Mar 12 2007 13:37, Cong WANG wrote: > > The following code is picked from drivers/kvm/kvm_main.c: > > static struct kvm_vcpu *vcpu_load(struct kvm *kvm, int vcpu_slot) > { > struct kvm_vcpu *vcpu = &kvm->vcpus[vcpu_slot]; > > mutex_lock(&vcpu->mutex); > if (unlikely(!vcpu->vmcs)) { > mutex_unlock(&vcpu->mutex); > return 0; > } > return kvm_arch_ops->vcpu_load(vcpu); > } > > Obviously, it used 0 rather than NULL when returning a pointer to > indicate an error. Should we fix such issue?
Indeed. If it was for me, something like that should throw a compile error.
>>[...] > I think it's more clear to indicate we are using a pointer rather than > an integer when we use NULL in kernel. But in userspace, using NULL is > for portbility of the program, although most (*just* most, NOT all) of > NULL's defination is ((void*)0). ;-)
NULL has the same bit pattern as the number zero. (I'm not saying the bit pattern is all zeroes. And I am not even sure if NULL ought to have the same pattern as zero.) So C++ could use (void *)0, if it would let itself :p
> >
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