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 21:40:14 +0200 Message-ID: <20160223194014.GA5241@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: > On Mon, Feb 22, 2016 at 11:08:59PM +0200, Jarkko Sakkinen wrote: > > On Fri, Feb 19, 2016 at 07:42:01AM -0500, Stefan Berger wrote: > > > From: Jason Gunthorpe > > > > > > Add a read/write semaphore around the ops function pointers so > > > ops can be set to null when the driver un-registers. > > > > > > Previously the tpm core expected module locking to be enough to > > > ensure that tpm_unregister could not be called during certain times, > > > however that hasn't been sufficient for a long time. > > > > Could you be more concrete with the scenario? You could describe > > a sequence of events where this could happen. > > echo 1 > /sys/.../remove > > Is basically the same as a module unload without requiring module > unload. module locking cannot be relied upon for correctness like this > ever since hot remove was added to the kernel. The 'remove' file applies only to PCI devices AFAIK. /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