From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [PATCH v3 04/11] tpm: Provide strong locking for device removal Date: Tue, 23 Feb 2016 22:43:02 +0200 Message-ID: <20160223204302.GA17368@intel.com> References: <1455885728-10315-1-git-send-email-stefanb@linux.vnet.ibm.com> <1455885728-10315-5-git-send-email-stefanb@linux.vnet.ibm.com> <20160222210844.GA3310@intel.com> <20160222222017.GC27228@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20160222222017.GC27228-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Jason Gunthorpe Cc: tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net On Mon, Feb 22, 2016 at 03:20:17PM -0700, Jason Gunthorpe wrote: > > I'm just thinking is the try_module_get() and module_put() even > > necessary after this change? You know that device is not unregistered > > from chip->ops field, which is protected by that RW-semaphore. > > The module locking is not about correctness. Some subsystems will hold > the module lock on their driver specifically to prevent rmmod as a > hint to the user that the driver module is being used by an open > /dev/tpmX for instance. Eg rtc does that. > > We need to decide if we want that for TPM or not. Orthogonal issue. > > I'm OK with getting rid of the module lock, TPM has a long lived > user space daemon, rtc does not. You might want to use TPM without a daemon on small embedded devices but on the other hand in these use cases the environment is fairly well controlled. I'm not sure which side to take. > Jason /Jarkko ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140