title: Synchronisation between process context and timer function
body: <p>I want to update a data structure atomically in both process context (in queuecommand function to be specific) and timer function. In process context, should I use <code>spin_lock_bh</code> or <code>spin_lock_irq</code> or just <code>spin_lock</code>?</p>
  
  <p>As per my understanding, we should use <code>spin_lock_bh</code> in queuecommand (process context) and just <code>spin_lock</code> in timer function. Am I correct?</p>