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Bluetooth: btusb: Fix race when waiting for BTUSB_DOWNLOADING

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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>
This commit is contained in:
Johan Hedberg 2015-01-30 10:58:54 +02:00 committed by Marcel Holtmann
parent 74d9daafa5
commit a087a98e07
1 changed files with 34 additions and 33 deletions
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67
drivers/bluetooth/btusb.c
View file

@ -334,6 +334,16 @@ struct btusb_data {
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 @@ static int btusb_recv_event_intel(struct hci_dev *hdev, struct sk_buff *skb)
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 @@ static int btusb_setup_intel_new(struct hci_dev *hdev)
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)) {