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

From	Greg KH <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v5 4/8] thunderbolt: Communication with the ICM (firmware)
Date	2016-07-29 23:50 +0200
Message-ID	<s0nPk-1RL-5@gated-at.bofh.it> (permalink)
References	<rZOHT-3yL-3@gated-at.bofh.it> <rZOHU-3yL-21@gated-at.bofh.it> <s0ncC-1Bv-23@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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@intel.com> 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...

Thread

[PATCH v5 0/8] thunderbolt: Introducing Thunderbolt(TM) networking Amir Levy <amir.jer.levy@intel.com> - 2016-07-28 10:20 +0200
  [PATCH v5 2/8] thunderbolt: Updating the register definitions Amir Levy <amir.jer.levy@intel.com> - 2016-07-28 10:20 +0200
  [PATCH v5 8/8] thunderbolt: Adding maintainer entry Amir Levy <amir.jer.levy@intel.com> - 2016-07-28 10:20 +0200
  [PATCH v5 7/8] thunderbolt: Networking doc Amir Levy <amir.jer.levy@intel.com> - 2016-07-28 10:20 +0200
  Re: [PATCH v5 5/8] thunderbolt: Networking state machine Lukas Wunner <lukas@wunner.de> - 2016-07-28 13:40 +0200
    RE: [PATCH v5 5/8] thunderbolt: Networking state machine "Levy, Amir (Jer)" <amir.jer.levy@intel.com> - 2016-07-31 14:00 +0200
  Re: [PATCH v5 4/8] thunderbolt: Communication with the ICM  (firmware) Stephen Hemminger <stephen@networkplumber.org> - 2016-07-29 23:10 +0200
    Re: [PATCH v5 4/8] thunderbolt: Communication with the ICM (firmware) Greg KH <gregkh@linuxfoundation.org> - 2016-07-29 23:50 +0200
      RE: [PATCH v5 4/8] thunderbolt: Communication with the ICM  (firmware) "Levy, Amir (Jer)" <amir.jer.levy@intel.com> - 2016-07-31 12:20 +0200
  Re: [PATCH v5 4/8] thunderbolt: Communication with the ICM  (firmware) Stephen Hemminger <stephen@networkplumber.org> - 2016-07-29 23:10 +0200
    RE: [PATCH v5 4/8] thunderbolt: Communication with the ICM  (firmware) "Levy, Amir (Jer)" <amir.jer.levy@intel.com> - 2016-07-31 14:10 +0200
  Re: [PATCH v5 6/8] thunderbolt: Networking transmit and receive Stephen Hemminger <stephen@networkplumber.org> - 2016-07-29 23:20 +0200
    RE: [PATCH v5 6/8] thunderbolt: Networking transmit and receive "Levy, Amir (Jer)" <amir.jer.levy@intel.com> - 2016-07-31 12:20 +0200
      Re: [PATCH v5 6/8] thunderbolt: Networking transmit and receive David Miller <davem@davemloft.net> - 2016-07-31 20:50 +0200
        RE: [PATCH v5 6/8] thunderbolt: Networking transmit and receive "Levy, Amir (Jer)" <amir.jer.levy@intel.com> - 2016-08-01 06:40 +0200

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