Bluetooth: bcm203x: Fix race condition on disconnect

When disconnecting a bcm203x device we kill and destroy the usb-urb, however,
there might still be a pending work-structure which resubmits the now invalid
urb. To avoid this race condition, we simply set a shutdown-flag and
synchronously kill the worker first.

This also adds a comment to all schedule_work()s, as it is really not clear
that they are used as replacement for short timers (which can be seen in the git
history).

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/bluetooth/bcm203x.c b/drivers/bluetooth/bcm203x.c
index 8b1b643a519b..ec743c2ddf9d 100644
--- a/drivers/bluetooth/bcm203x.c
+++ b/drivers/bluetooth/bcm203x.c
@@ -24,6 +24,7 @@
 
 #include <linux/module.h>
 
+#include <linux/atomic.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/slab.h>
@@ -65,6 +66,7 @@ struct bcm203x_data {
         unsigned long           state;
 
         struct work_struct      work;
+        atomic_t                shutdown;
 
         struct urb              *urb;
         unsigned char           *buffer;
@@ -97,6 +99,7 @@ static void bcm203x_complete(struct urb *urb)
 
                 data->state = BCM203X_SELECT_MEMORY;
 
+                /* use workqueue to have a small delay */
                 schedule_work(&data->work);
                 break;
 
@@ -155,6 +158,9 @@ static void bcm203x_work(struct work_struct *work)
         struct bcm203x_data *data =
                 container_of(work, struct bcm203x_data, work);
 
+        if (atomic_read(&data->shutdown))
+                return;
+
         if (usb_submit_urb(data->urb, GFP_ATOMIC) < 0)
                 BT_ERR("Can't submit URB");
 }
@@ -243,6 +249,7 @@ static int bcm203x_probe(struct usb_interface *intf, const struct usb_device_id
 
         usb_set_intfdata(intf, data);
 
+        /* use workqueue to have a small delay */
         schedule_work(&data->work);
 
         return 0;
@@ -254,6 +261,9 @@ static void bcm203x_disconnect(struct usb_interface *intf)
 
         BT_DBG("intf %p", intf);
 
+        atomic_inc(&data->shutdown);
+        cancel_work_sync(&data->work);
+
         usb_kill_urb(data->urb);
 
         usb_set_intfdata(intf, NULL);