From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [driver-core PATCH v5 4/9] driver core: Move async_synchronize_full call Date: Mon, 05 Nov 2018 17:04:49 -0800 Message-ID: <1541466289.196084.176.camel@acm.org> References: <154145223352.29224.8912797012647157172.stgit@ahduyck-desk1.jf.intel.com> <154145231976.29224.39638353241256116.stgit@ahduyck-desk1.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <154145231976.29224.39638353241256116.stgit-+uVpp3jiz/RcxmDmkzA3yGt3HXsI98Cx0E9HWUfgJXw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: Alexander Duyck , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org Cc: len.brown-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, rafael-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, jiangshanlai-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, pavel-+ZI9xUNit7I@public.gmane.org, zwisler-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org List-Id: linux-pm@vger.kernel.org On Mon, 2018-11-05 at 13:11 -0800, Alexander Duyck wrote: > This patch moves the async_synchronize_full call out of > __device_release_driver and into driver_detach. > > The idea behind this is that the async_synchronize_full call will only > guarantee that any existing async operations are flushed. This doesn't do > anything to guarantee that a hotplug event that may occur while we are > doing the release of the driver will not be asynchronously scheduled. > > By moving this into the driver_detach path we can avoid potential deadlocks > as we aren't holding the device lock at this point and we should not have > the driver we want to flush loaded so the flush will take care of any > asynchronous events the driver we are detaching might have scheduled. > > Signed-off-by: Alexander Duyck > --- > drivers/base/dd.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 76c40fe69463..e74cefeb5b69 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -975,9 +975,6 @@ static void __device_release_driver(struct device *dev, struct device *parent) > > drv = dev->driver; > if (drv) { > - if (driver_allows_async_probing(drv)) > - async_synchronize_full(); > - > while (device_links_busy(dev)) { > __device_driver_unlock(dev, parent); > > @@ -1087,6 +1084,9 @@ void driver_detach(struct device_driver *drv) > struct device_private *dev_prv; > struct device *dev; > > + if (driver_allows_async_probing(drv)) > + async_synchronize_full(); > + > for (;;) { > spin_lock(&drv->p->klist_devices.k_lock); > if (list_empty(&drv->p->klist_devices.k_list)) { Have you considered to move that async_synchronize_full() call into bus_remove_driver()? Verifying the correctness of this patch requires to check whether the async_synchronize_full() comes after the klist_remove(&drv->p->knode_bus) call. That verification is easier when the async_synchronize_full() call occurs in bus_remove_driver() instead of in driver_detach(). Thanks, Bart.