staging: usbip: vhci: fix oops on subsequent attach

vhci_rx/vhci_tx threads are created once but stopped each
time the vdev is shut down. On subsequent attach wake_up_process()
oopses trying to access the stopped threads.

This patch does as before the kthread conversion which is to
create the threads each time a device is attached and stop the
threads when the device is shut down.

Signed-off-by: Max Vozeler <max@hinterhof.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Takahiro Hirofuchi <hirofuchi@users.sourceforge.net>
Cc: Arjan Mels <arjan.mels@gmx.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 8 insertions, 8 deletions

diff --git a/drivers/staging/usbip/vhci_hcd.c b/drivers/staging/usbip/vhci_hcd.c
index 0f02a4b12ae4..14caae279f7e 100644
--- a/drivers/staging/usbip/vhci_hcd.c
+++ b/drivers/staging/usbip/vhci_hcd.c
@@ -876,8 +876,10 @@ static void vhci_shutdown_connection(struct usbip_device *ud)
         }
 
         /* kill threads related to this sdev, if v.c. exists */
-        kthread_stop(vdev->ud.tcp_rx);
-        kthread_stop(vdev->ud.tcp_tx);
+        if (vdev->ud.tcp_rx)
+                kthread_stop(vdev->ud.tcp_rx);
+        if (vdev->ud.tcp_tx)
+                kthread_stop(vdev->ud.tcp_tx);
 
         usbip_uinfo("stop threads\n");
 
@@ -949,9 +951,6 @@ static void vhci_device_init(struct vhci_device *vdev)
 {
         memset(vdev, 0, sizeof(*vdev));
 
-        vdev->ud.tcp_rx = kthread_create(vhci_rx_loop, &vdev->ud, "vhci_rx");
-        vdev->ud.tcp_tx = kthread_create(vhci_tx_loop, &vdev->ud, "vhci_tx");
-
         vdev->ud.side   = USBIP_VHCI;
         vdev->ud.status = VDEV_ST_NULL;
         /* vdev->ud.lock   = SPIN_LOCK_UNLOCKED; */
diff --git a/drivers/staging/usbip/vhci_sysfs.c b/drivers/staging/usbip/vhci_sysfs.c
index 3f2459f30415..e2dadbd5ef1e 100644
--- a/drivers/staging/usbip/vhci_sysfs.c
+++ b/drivers/staging/usbip/vhci_sysfs.c
@@ -21,6 +21,7 @@
 #include "vhci.h"
 
 #include <linux/in.h>
+#include <linux/kthread.h>
 
 /* TODO: refine locking ?*/
 
@@ -220,13 +221,13 @@ static ssize_t store_attach(struct device *dev, struct device_attribute *attr,
         vdev->ud.tcp_socket = socket;
         vdev->ud.status     = VDEV_ST_NOTASSIGNED;
 
-        wake_up_process(vdev->ud.tcp_rx);
-        wake_up_process(vdev->ud.tcp_tx);
-
         spin_unlock(&vdev->ud.lock);
         spin_unlock(&the_controller->lock);
         /* end the lock */
 
+        vdev->ud.tcp_rx = kthread_run(vhci_rx_loop, &vdev->ud, "vhci_rx");
+        vdev->ud.tcp_tx = kthread_run(vhci_tx_loop, &vdev->ud, "vhci_tx");
+
         rh_port_connect(rhport, speed);
 
         return count;