Subject: Re: [PATCH v5 4/8] thunderbolt: Communication with the ICM (firmware)

From: Greg KH <[email-masked]>
Date: Fri, 29 Jul 2016 14:48:38 -0700

On Fri, Jul 29, 2016 at 02:02:24PM -0700, Stephen Hemminger wrote:
> On Thu, 28 Jul 2016 11:15:17 +0300
> Amir Levy <[email-masked]> wrote:
> 
> > +static LIST_HEAD(controllers_list);
> > +static DECLARE_RWSEM(controllers_list_rwsem);
> 
> Why use a semaphore when simple spinlock or mutex would be better?

And never use a RW semaphore unless you can benchmark the difference
from a normal lock.  If you can't benchmark it, then don't use it...