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

[Greg KH]

On Fri, Jul 29, 2016 at 02:02:24PM -0700, Stephen Hemminger wrote:
> On Thu, 28 Jul 2016 11:15:17 +0300
> Amir Levy <amir.jer.levy@xxxxxxxxx> 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...