linux-kernel - [RESEND PATCH v1] driver core: fix possible missing of device probe

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Date:	Sat,  5 Jan 2013 11:22:40 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, Ming Lei <ming.lei@...onical.com>
Subject: [RESEND PATCH v1] driver core: fix possible missing of device probe

Inside bus_add_driver(), one device might be added(device_add()) 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() to fix the
problem.

Signed-off-by: Ming Lei <ming.lei@...onical.com>
---
v1:
	- remove memory barrier part of previous commit log because
	klist lock of 'bus->p->klist_drivers' is held during both
	adding driver into the list and iterating the driver list,
	so the new added driver can always be perceived immediately
	on other CPUs.
---
 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

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