patch "mei: bus: move hw module get/put to probe/release" added to char-misc-next

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mei: bus: move hw module get/put to probe/release

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


From b5958faa34e2f99f3475ad89c52d98dfea079d33 Mon Sep 17 00:00:00 2001
From: Alexander Usyskin <alexander.usyskin@intel.com>
Date: Mon, 25 Feb 2019 11:09:28 +0200
Subject: mei: bus: move hw module get/put to probe/release

Fix unbalanced module reference counting during internal reset, which
prevents the drivers unloading.
Tracking mei_me/txe modules on mei client bus via
mei_cldev_enable/disable is error prone due to possible internal
reset flow, where clients are disconnected underneath.
Moving reference counting to probe and release of mei bus client
driver solves this issue in simplest way, as each client provides only
a single connection to a client bus driver.

Cc: <stable@vger.kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/misc/mei/bus.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index e5456faf00e6..65bec998eb6e 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -540,17 +540,9 @@ int mei_cldev_enable(struct mei_cl_device *cldev)
 		goto out;
 	}
 
-	if (!mei_cl_bus_module_get(cldev)) {
-		dev_err(&cldev->dev, "get hw module failed");
-		ret = -ENODEV;
-		goto out;
-	}
-
 	ret = mei_cl_connect(cl, cldev->me_cl, NULL);
-	if (ret < 0) {
+	if (ret < 0)
 		dev_err(&cldev->dev, "cannot connect\n");
-		mei_cl_bus_module_put(cldev);
-	}
 
 out:
 	mutex_unlock(&bus->device_lock);
@@ -613,7 +605,6 @@ int mei_cldev_disable(struct mei_cl_device *cldev)
 	if (err < 0)
 		dev_err(bus->dev, "Could not disconnect from the ME client\n");
 
-	mei_cl_bus_module_put(cldev);
 out:
 	/* Flush queues and remove any pending read */
 	mei_cl_flush_queues(cl, NULL);
@@ -724,9 +715,16 @@ static int mei_cl_device_probe(struct device *dev)
 	if (!id)
 		return -ENODEV;
 
+	if (!mei_cl_bus_module_get(cldev)) {
+		dev_err(&cldev->dev, "get hw module failed");
+		return -ENODEV;
+	}
+
 	ret = cldrv->probe(cldev, id);
-	if (ret)
+	if (ret) {
+		mei_cl_bus_module_put(cldev);
 		return ret;
+	}
 
 	__module_get(THIS_MODULE);
 	return 0;
@@ -754,6 +752,7 @@ static int mei_cl_device_remove(struct device *dev)
 
 	mei_cldev_unregister_callbacks(cldev);
 
+	mei_cl_bus_module_put(cldev);
 	module_put(THIS_MODULE);
 	dev->driver = NULL;
 	return ret;
-- 
2.21.0