Bluetooth: btusb: Fix race when waiting for BTUSB_DOWNLOADING
The test for BTUSB_DOWNLOADING must be after adding to the wait queue
and setting the TASK_INTERRUPTIBLE state. Otherwise the flag may get
cleared after we test for it and we end up getting a timeout since
schedule_timeout() waits for the full duration. This patch uses a
wait_on_bit_timeout() + wake_up_bit(). To perform the task both
race-free as well as in a much simpler way.
Since there's no global wait_on_bit_timeout() helper yet (even though
all the building blocks for it are in place) this patch creates a
temporary local btusb copy of it until the global one has made it to
upstream trees.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 86f3d92..98341a4 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -334,6 +334,16 @@
int (*recv_bulk)(struct btusb_data *data, void *buffer, int count);
};
+static int btusb_wait_on_bit_timeout(void *word, int bit, unsigned long timeout,
+ unsigned mode)
+{
+ might_sleep();
+ if (!test_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit_timeout(word, bit, bit_wait_timeout,
+ mode, timeout);
+}
+
static inline void btusb_free_frags(struct btusb_data *data)
{
unsigned long flags;
@@ -1800,8 +1810,10 @@
if (test_and_clear_bit(BTUSB_DOWNLOADING,
&data->flags) &&
- test_bit(BTUSB_FIRMWARE_LOADED, &data->flags))
- wake_up_interruptible(&hdev->req_wait_q);
+ test_bit(BTUSB_FIRMWARE_LOADED, &data->flags)) {
+ smp_mb__after_atomic();
+ wake_up_bit(&data->flags, BTUSB_DOWNLOADING);
+ }
}
/* When switching to the operational firmware the device
@@ -2165,43 +2177,32 @@
set_bit(BTUSB_FIRMWARE_LOADED, &data->flags);
+ BT_INFO("%s: Waiting for firmware download to complete", hdev->name);
+
/* Before switching the device into operational mode and with that
* booting the loaded firmware, wait for the bootloader notification
* that all fragments have been successfully received.
*
- * When the event processing receives the notification, then this
- * flag will be cleared. So just in case that happens really quickly,
- * check it first before adding the wait queue.
+ * When the event processing receives the notification, then the
+ * BTUSB_DOWNLOADING flag will be cleared.
+ *
+ * The firmware loading should not take longer than 5 seconds
+ * and thus just timeout if that happens and fail the setup
+ * of this device.
*/
- if (test_bit(BTUSB_DOWNLOADING, &data->flags)) {
- DECLARE_WAITQUEUE(wait, current);
- signed long timeout;
+ err = btusb_wait_on_bit_timeout(&data->flags, BTUSB_DOWNLOADING,
+ msecs_to_jiffies(5000),
+ TASK_INTERRUPTIBLE);
+ if (err == 1) {
+ BT_ERR("%s: Firmware loading interrupted", hdev->name);
+ err = -EINTR;
+ goto done;
+ }
- BT_INFO("%s: Waiting for firmware download to complete",
- hdev->name);
-
- add_wait_queue(&hdev->req_wait_q, &wait);
- set_current_state(TASK_INTERRUPTIBLE);
-
- /* The firmware loading should not take longer than 5 seconds
- * and thus just timeout if that happens and fail the setup
- * of this device.
- */
- timeout = schedule_timeout(msecs_to_jiffies(5000));
-
- remove_wait_queue(&hdev->req_wait_q, &wait);
-
- if (signal_pending(current)) {
- BT_ERR("%s: Firmware loading interrupted", hdev->name);
- err = -EINTR;
- goto done;
- }
-
- if (!timeout) {
- BT_ERR("%s: Firmware loading timeout", hdev->name);
- err = -ETIMEDOUT;
- goto done;
- }
+ if (err) {
+ BT_ERR("%s: Firmware loading timeout", hdev->name);
+ err = -ETIMEDOUT;
+ goto done;
}
if (test_bit(BTUSB_FIRMWARE_FAILED, &data->flags)) {