[PATCH 1/1] mei: bus: don't clean driver pointer

Aaron Ma aaron.ma at canonical.com
Wed Sep 2 06:58:31 UTC 2020

From: Alexander Usyskin <alexander.usyskin at intel.com>

BugLink: https://bugs.launchpad.net/bugs/1893609

It's not needed to set driver to NULL in mei_cl_device_remove()
which is bus_type remove() handler as this is done anyway
in __device_release_driver().

Actually this is causing an endless loop in driver_detach()
on ubuntu patched kernel, while removing (rmmod) the mei_hdcp module.
The reason list_empty(&drv->p->klist_devices.k_list) is always not-empty.
as the check is always true in  __device_release_driver()
	if (dev->driver != drv)

The non upstream patch is causing this behavior, titled:
'vfio -- release device lock before userspace requests'

Nevertheless the fix is correct also for the upstream.

Link: https://patchwork.ozlabs.org/project/ubuntu-kernel/patch/20180912085046.3401-2-apw@canonical.com/
Cc: <stable at vger.kernel.org>
Cc: Andy Whitcroft <apw at canonical.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin at intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler at intel.com>
Link: https://lore.kernel.org/r/20200628225359.2185929-1-tomas.winkler@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit e852c2c251ed9c23ae6e3efebc5ec49adb504207)
Signed-off-by: Aaron Ma <aaron.ma at canonical.com>
 drivers/misc/mei/bus.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index 8d468e0a950a..f476dbc7252b 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -745,9 +745,8 @@ static int mei_cl_device_remove(struct device *dev)
-	dev->driver = NULL;
-	return ret;
+	return ret;
 static ssize_t name_show(struct device *dev, struct device_attribute *a,

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