From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754855Ab2I1Aw6 (ORCPT ); Thu, 27 Sep 2012 20:52:58 -0400 Received: from mail-da0-f46.google.com ([209.85.210.46]:40752 "EHLO mail-da0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753261Ab2I1Aw4 (ORCPT ); Thu, 27 Sep 2012 20:52:56 -0400 From: Ming Lei To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Russell King , Ming Lei , Subject: [PATCH] driver core: fix possible missing of device probe Date: Fri, 28 Sep 2012 08:52:43 +0800 Message-Id: <1348793563-19186-1-git-send-email-ming.lei@canonical.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Inside bus_add_driver(), one device might be added into the bus or probed which is triggered by deferred probe just after completing of driver_attach() and before 'klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers)', so the device won't be probed by this driver. This patch moves the below line 'klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers)' before driver_attach() inside bus_add_driver(). So fixes the problem since the below way can guarantee that no probe(dev) may be lost. CPU0 CPU1 driver_register ... write(bus->driver_list) smp_mb() read(bus->device_list) ... device_add /* bus_add_device */ write(bus->device_list) smp_mb() /* bus_probe_device*/ read(bus->driver_list) And the smp_mb() has been implicit by UNLOCK+LOCK of 'klist' according to 'VARIETIES OF MEMORY BARRIER' part of Documentation/memory-barriers.txt. Reported-and-Tested-by: Russell King Cc: Signed-off-by: Ming Lei --- drivers/base/bus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 181ed26..3b5bddb 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -714,12 +714,12 @@ int bus_add_driver(struct device_driver *drv) if (error) goto out_unregister; + klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers); if (drv->bus->p->drivers_autoprobe) { error = driver_attach(drv); if (error) goto out_unregister; } - klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers); module_add_driver(drv->owner, drv); error = driver_create_file(drv, &driver_attr_uevent); -- 1.7.9.5