From a087a98e0767cf6c4f2480e6de5441497c9ba5b7 Mon Sep 17 00:00:00 2001 From: Johan Hedberg Date: Fri, 30 Jan 2015 10:58:54 +0200 Subject: [PATCH] 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 Signed-off-by: Marcel Holtmann --- drivers/bluetooth/btusb.c | 67 ++++++++++++++++++++------------------- 1 file changed, 34 insertions(+), 33 deletions(-) diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c index 86f3d92de22a..98341a463f30 100644 --- a/drivers/bluetooth/btusb.c +++ b/drivers/bluetooth/btusb.c @@ -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; - - 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; - } + 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; + } - 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)) { -- 2.20.1