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authorAlan Stern <stern@rowland.harvard.edu>2008-12-19 10:27:56 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2009-01-07 10:00:12 -0800
commitdf718962bf91c7bd345060aadaa24b03f6140b07 (patch)
treecfae38a59ccb944a2af3ef39a14d4d854cba64a3
parent6fd9086a518d4f14213a32fe6c9ac17fabebbc1e (diff)
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USB: cancel pending Set-Config requests if userspace gets there first
This patch (as1195) eliminates a potential problem identified by Oliver Neukum. When a driver queues an asynchronous Set-Config request using usb_driver_set_configuration(), the request should be cancelled if userspace changes the configuration first. The patch introduces a linked list of pending async Set-Config requests, and uses it to invalidate the requests for a particular device whenever that device's configuration is set. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Cc: Oliver Neukum <oliver@neukum.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/usb/core/message.c42
1 files changed, 38 insertions, 4 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 7943901c641..5589686981f 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -18,6 +18,8 @@
#include "hcd.h" /* for usbcore internals */
#include "usb.h"
+static void cancel_async_set_config(struct usb_device *udev);
+
struct api_context {
struct completion done;
int status;
@@ -1636,6 +1638,9 @@ free_interfaces:
if (dev->state != USB_STATE_ADDRESS)
usb_disable_device(dev, 1); /* Skip ep0 */
+ /* Get rid of pending async Set-Config requests for this device */
+ cancel_async_set_config(dev);
+
ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
USB_REQ_SET_CONFIGURATION, 0, configuration, 0,
NULL, 0, USB_CTRL_SET_TIMEOUT);
@@ -1725,10 +1730,14 @@ free_interfaces:
return 0;
}
+static LIST_HEAD(set_config_list);
+static DEFINE_SPINLOCK(set_config_lock);
+
struct set_config_request {
struct usb_device *udev;
int config;
struct work_struct work;
+ struct list_head node;
};
/* Worker routine for usb_driver_set_configuration() */
@@ -1736,14 +1745,35 @@ static void driver_set_config_work(struct work_struct *work)
{
struct set_config_request *req =
container_of(work, struct set_config_request, work);
+ struct usb_device *udev = req->udev;
- usb_lock_device(req->udev);
- usb_set_configuration(req->udev, req->config);
- usb_unlock_device(req->udev);
- usb_put_dev(req->udev);
+ usb_lock_device(udev);
+ spin_lock(&set_config_lock);
+ list_del(&req->node);
+ spin_unlock(&set_config_lock);
+
+ if (req->config >= -1) /* Is req still valid? */
+ usb_set_configuration(udev, req->config);
+ usb_unlock_device(udev);
+ usb_put_dev(udev);
kfree(req);
}
+/* Cancel pending Set-Config requests for a device whose configuration
+ * was just changed
+ */
+static void cancel_async_set_config(struct usb_device *udev)
+{
+ struct set_config_request *req;
+
+ spin_lock(&set_config_lock);
+ list_for_each_entry(req, &set_config_list, node) {
+ if (req->udev == udev)
+ req->config = -999; /* Mark as cancelled */
+ }
+ spin_unlock(&set_config_lock);
+}
+
/**
* usb_driver_set_configuration - Provide a way for drivers to change device configurations
* @udev: the device whose configuration is being updated
@@ -1775,6 +1805,10 @@ int usb_driver_set_configuration(struct usb_device *udev, int config)
req->config = config;
INIT_WORK(&req->work, driver_set_config_work);
+ spin_lock(&set_config_lock);
+ list_add(&req->node, &set_config_list);
+ spin_unlock(&set_config_lock);
+
usb_get_dev(udev);
schedule_work(&req->work);
return 0;