How to Upgrade Kernel with Ansible Modules

I am newbie in Ansible and I would like to upgrade all of our environment's kernel. I've checked the modules but I have couple of questions about it. My main point is upgrade only kernel. Some VMs have another repositories like web servers, nosql etc. So if I write the playbook like this:

- name: Disable all repositories except rhel-7-server-rpms
       rhsm_repository:
         name: rhel-7-server-rpms
         purge: True
- name: YUM Update
       yum:
         name: '*'
         state: latest

First, It disables all repositories except rhel-7server-rpms which has the latest kernel version. Then, it will start yum update procedure. First question is, does it work correctly like I want, and do I need to add one more module between them like:

-name: Subscription Manager Refresh
  command: subscription-manager refresh or yum clear all

Secondly, does it solve my problem with one module:

- name: update specific repo from rpm
  yum:
    name: rhel-7-server-rpms
    state: latest

If one or both of them works correctly, which one should I use?

Thanks in advence.