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    SubjectRe: Style Question

    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


    >
    >

    Jan
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