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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Shuah Khan (Samsung OSG)" <shuah@kernel.org>
Date:   Sat, 22 Sep 2018 01:15:42 +0100
Message-ID: <lsq.1537575342.667794728@decadent.org.uk>
Subject: [PATCH 3.16 09/63] usbip: usbip_host: run rebind from exit when
 module is removed
In-Reply-To: <lsq.1537575341.194909669@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.58-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Shuah Khan (Samsung OSG)" <shuah@kernel.org>

commit 7510df3f29d44685bab7b1918b61a8ccd57126a9 upstream.

After removing usbip_host module, devices it releases are left without
a driver. For example, when a keyboard or a mass storage device are
bound to usbip_host when it is removed, these devices are no longer
bound to any driver.

Fix it to run device_attach() from the module exit routine to restore
the devices to their original drivers. This includes cleanup changes
and moving device_attach() code to a common routine to be called from
rebind_store() and usbip_host_exit().

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust filenames]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/staging/usbip/stub_dev.c  |  6 +---
 drivers/staging/usbip/stub_main.c | 60 +++++++++++++++++++++++++++++------
 2 files changed, 52 insertions(+), 14 deletions(-)

--- a/drivers/staging/usbip/stub_dev.c
+++ b/drivers/staging/usbip/stub_dev.c
@@ -490,12 +490,8 @@ static void stub_disconnect(struct usb_d
 	busid_priv->sdev = NULL;
 	stub_device_free(sdev);
 
-	if (busid_priv->status == STUB_BUSID_ALLOC) {
+	if (busid_priv->status == STUB_BUSID_ALLOC)
 		busid_priv->status = STUB_BUSID_ADDED;
-	} else {
-		busid_priv->status = STUB_BUSID_OTHER;
-		del_match_busid((char *)udev_busid);
-	}
 }
 
 #ifdef CONFIG_PM
--- a/drivers/staging/usbip/stub_main.c
+++ b/drivers/staging/usbip/stub_main.c
@@ -28,6 +28,7 @@
 #define DRIVER_DESC "USB/IP Host Driver"
 
 struct kmem_cache *stub_priv_cache;
+
 /*
  * busid_tables defines matching busids that usbip can grab. A user can change
  * dynamically what device is locally used and what device is exported to a
@@ -188,6 +189,51 @@ static ssize_t store_match_busid(struct
 static DRIVER_ATTR(match_busid, S_IRUSR | S_IWUSR, show_match_busid,
 		   store_match_busid);
 
+static int do_rebind(char *busid, struct bus_id_priv *busid_priv)
+{
+	int ret;
+
+	/* device_attach() callers should hold parent lock for USB */
+	if (busid_priv->udev->dev.parent)
+		device_lock(busid_priv->udev->dev.parent);
+	ret = device_attach(&busid_priv->udev->dev);
+	if (busid_priv->udev->dev.parent)
+		device_unlock(busid_priv->udev->dev.parent);
+	if (ret < 0) {
+		dev_err(&busid_priv->udev->dev, "rebind failed\n");
+		return ret;
+	}
+	return 0;
+}
+
+static void stub_device_rebind(void)
+{
+#if IS_MODULE(CONFIG_USBIP_HOST)
+	struct bus_id_priv *busid_priv;
+	int i;
+
+	/* update status to STUB_BUSID_OTHER so probe ignores the device */
+	spin_lock(&busid_table_lock);
+	for (i = 0; i < MAX_BUSID; i++) {
+		if (busid_table[i].name[0] &&
+		    busid_table[i].shutdown_busid) {
+			busid_priv = &(busid_table[i]);
+			busid_priv->status = STUB_BUSID_OTHER;
+		}
+	}
+	spin_unlock(&busid_table_lock);
+
+	/* now run rebind */
+	for (i = 0; i < MAX_BUSID; i++) {
+		if (busid_table[i].name[0] &&
+		    busid_table[i].shutdown_busid) {
+			busid_priv = &(busid_table[i]);
+			do_rebind(busid_table[i].name, busid_priv);
+		}
+	}
+#endif
+}
+
 static ssize_t rebind_store(struct device_driver *dev, const char *buf,
 				 size_t count)
 {
@@ -208,16 +254,9 @@ static ssize_t rebind_store(struct devic
 	/* mark the device for deletion so probe ignores it during rescan */
 	bid->status = STUB_BUSID_OTHER;
 
-	/* device_attach() callers should hold parent lock for USB */
-	if (bid->udev->dev.parent)
-		device_lock(bid->udev->dev.parent);
-	ret = device_attach(&bid->udev->dev);
-	if (bid->udev->dev.parent)
-		device_unlock(bid->udev->dev.parent);
-	if (ret < 0) {
-		dev_err(&bid->udev->dev, "rebind failed\n");
+	ret = do_rebind((char *) buf, bid);
+	if (ret < 0)
 		return ret;
-	}
 
 	/* delete device from busid_table */
 	del_match_busid((char *) buf);
@@ -343,6 +382,9 @@ static void __exit usbip_host_exit(void)
 	 */
 	usb_deregister_device_driver(&stub_driver);
 
+	/* initiate scan to attach devices */
+	stub_device_rebind();
+
 	kmem_cache_destroy(stub_priv_cache);
 }