ioctl callchain cut short

The ioctl call chain can be followed in only one direction, not in the other.

semcode> callers kvm_vcpu_ioctl
Finding all functions that call: kvm_vcpu_ioctl

=== Direct Callers ===
1 functions directly call 'kvm_vcpu_ioctl':
1. kvm_vcpu_compat_ioctl

=== Indirect Callers ===
4 call sites can reach it through a function pointer:
1. compat_ptr_ioctl at fs/ioctl.c:634 [member_arrow]
installed in file_operations::unlocked_ioctl at virt/kvm/kvm_main.c:4101 (receiver type matches)
2. ecryptfs_unlocked_ioctl at fs/ecryptfs/file.c:379 [member_arrow]
installed in file_operations::unlocked_ioctl at virt/kvm/kvm_main.c:4101 (receiver type matches)
3. v4l2_compat_ioctl32 at drivers/media/v4l2-core/v4l2-compat-ioctl32.c:1197 [member_arrow]
installed in file_operations::unlocked_ioctl at virt/kvm/kvm_main.c:4101 (receiver type matches)
4. vfs_ioctl at fs/ioctl.c:51 [member_arrow]
installed in file_operations::unlocked_ioctl at virt/kvm/kvm_main.c:4101 (receiver type matches)
semcode> calls vfs_ioctl
Finding all functions called by: vfs_ioctl
Info: Function 'vfs_ioctl' doesn't call any other functions