Re: [PATCH] Bluetooth: hidp: Stop I/O on shutdown

[Gustavo Padovan <padovan-Y3ZbgMPKUGA34EUeqzHoZw@public.gmane.org>]

Hi David,

Sorry for the big delay to respond to this.

* David Herrmann <dh.herrmann-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org> [2011-08-26 14:06:02 +0200]:

> Current hidp driver purges the in/out queue on HID shutdown, but does
> not prevent further I/O. If a driver uses hidp_output_raw_report or
> hidp_get_raw_report during shutdown, the driver hangs for 5 or 10
> seconds per call until it gets a timeout.
> That is, if the output queue of an HID driver has 10 messages pending,
> it will take 50s until hid_destroy_device() will return. The
> hidp_session_sem semaphore is held during shutdown so no other HID
> device may be added/removed during this time.
> 
> This patch makes hidp_output_raw_report and hidp_get_raw_report fail if
> session->terminate is true. Also hidp_session will wakeup all current
> calls to these functions to cancel the current operations.
> 
> We already purge the current I/O queues on hidp_stop(), so this data loss
> does not change the behaviour of the HID drivers.
> 
> Signed-off-by: David Herrmann <dh.herrmann-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
> ---
>  net/bluetooth/hidp/core.c |   40 ++++++++++++++++++++++++++--------------
>  1 files changed, 26 insertions(+), 14 deletions(-)
> 
> diff --git a/net/bluetooth/hidp/core.c b/net/bluetooth/hidp/core.c
> index 4423e3a..e134528 100644
> --- a/net/bluetooth/hidp/core.c
> +++ b/net/bluetooth/hidp/core.c
> @@ -255,6 +255,9 @@ static int __hidp_send_ctrl_message(struct hidp_session *session,
>  
>  	BT_DBG("session %p data %p size %d", session, data, size);
>  
> +	if (atomic_read(&session->terminate))
> +		return -EIO;
> +
>  	skb = alloc_skb(size + 1, GFP_ATOMIC);
>  	if (!skb) {
>  		BT_ERR("Can't allocate memory for new frame");
> @@ -320,6 +323,13 @@ static int hidp_send_report(struct hidp_session *session, struct hid_report *rep
>  	return hidp_queue_report(session, buf, rsize);
>  }
>  
> +static void hidp_wakeup_reportq(struct hidp_session *session)
> +{
> +	clear_bit(HIDP_WAITING_FOR_SEND_ACK, &session->flags);
> +	clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> +	wake_up_interruptible(&session->report_queue);
> +}
> +
>  static int hidp_get_raw_report(struct hid_device *hid,
>  		unsigned char report_number,
>  		unsigned char *data, size_t count,
> @@ -329,6 +339,7 @@ static int hidp_get_raw_report(struct hid_device *hid,
>  	struct sk_buff *skb;
>  	size_t len;
>  	int numbered_reports = hid->report_enum[report_type].numbered;
> +	int ret;
>  
>  	switch (report_type) {
>  	case HID_FEATURE_REPORT:
> @@ -352,8 +363,9 @@ static int hidp_get_raw_report(struct hid_device *hid,
>  	session->waiting_report_number = numbered_reports ? report_number : -1;
>  	set_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
>  	data[0] = report_number;
> -	if (hidp_send_ctrl_message(hid->driver_data, report_type, data, 1))
> -		goto err_eio;
> +	ret = hidp_send_ctrl_message(hid->driver_data, report_type, data, 1);
> +	if (ret)
> +		goto err;
>  
>  	/* Wait for the return of the report. The returned report
>  	   gets put in session->report_return.  */
> @@ -365,11 +377,13 @@ static int hidp_get_raw_report(struct hid_device *hid,
>  			5*HZ);
>  		if (res == 0) {
>  			/* timeout */
> -			goto err_eio;
> +			ret = -EIO;
> +			goto err;
>  		}
>  		if (res < 0) {
>  			/* signal */
> -			goto err_restartsys;
> +			ret = -ERESTARTSYS;
> +			goto err;
>  		}
>  	}
>  
> @@ -390,14 +404,10 @@ static int hidp_get_raw_report(struct hid_device *hid,
>  
>  	return len;
>  
> -err_restartsys:
> -	clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> -	mutex_unlock(&session->report_mutex);
> -	return -ERESTARTSYS;
> -err_eio:
> +err:
>  	clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
>  	mutex_unlock(&session->report_mutex);
> -	return -EIO;
> +	return ret;
>  }
>  
>  static int hidp_output_raw_report(struct hid_device *hid, unsigned char *data, size_t count,
> @@ -422,11 +432,10 @@ static int hidp_output_raw_report(struct hid_device *hid, unsigned char *data, s
>  
>  	/* Set up our wait, and send the report request to the device. */
>  	set_bit(HIDP_WAITING_FOR_SEND_ACK, &session->flags);
> -	if (hidp_send_ctrl_message(hid->driver_data, report_type,
> -			data, count)) {
> -		ret = -ENOMEM;
> +	ret = hidp_send_ctrl_message(hid->driver_data, report_type, data,
> +									count);
> +	if (ret)
>  		goto err;
> -	}
>  
>  	/* Wait for the ACK from the device. */
>  	while (test_bit(HIDP_WAITING_FOR_SEND_ACK, &session->flags)) {
> @@ -733,6 +742,9 @@ static int hidp_session(void *arg)
>  	remove_wait_queue(sk_sleep(intr_sk), &intr_wait);
>  	remove_wait_queue(sk_sleep(ctrl_sk), &ctrl_wait);
>  
> +	atomic_inc(&session->terminate);

At this point seeems that terminate is already > 1.

> +	hidp_wakeup_reportq(session);

just inline hidp_wakeup_reportq here, no need to create a function for this.

	Gustavo