Re: [PATCH 4/5] uas: add dead request list

[Sarah Sharp]

Don't you need to send an ABORT TASK message to the device to cancel the
outstanding request for that stream ID?  I don't see that in this code.
I see lots of URB cancellation code, but nothing to remove the request
from the device-side queue.

Does this code currently handle the case where a device refuses to
respond to a SCSI request, and the upper layers attempt to cancel that
request?  Or does it simply ensure that SCSI bus reset works?

I'm not comfortable with removing CONFIG_BROKEN until the upper layers
can cancel one outstanding request.

Plus, as Joe mentioned, this code is full of BUG_ON(), which is not
friendly to users, and doesn't increase my confidence that the driver is
ready to have CONFIG_BROKEN removed.

Sarah Sharp

On Mon, Sep 02, 2013 at 01:25:28PM +0200, Gerd Hoffmann wrote:
> This patch adds a new list where all requests which are canceled are
> added to, so we don't loose them.  Then, after killing all inflight
> urbs on bus reset (and disconnect) we'll walk over the list and clean
> them up.
> 
> Without this we can end up with aborted requests lingering around in
> case of status pipe transfer errors.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
>  drivers/usb/storage/uas.c | 69 +++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 61 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
> index a63972a..9dfb8f9 100644
> --- a/drivers/usb/storage/uas.c
> +++ b/drivers/usb/storage/uas.c
> @@ -78,6 +78,7 @@ struct uas_cmd_info {
>  	struct urb *data_in_urb;
>  	struct urb *data_out_urb;
>  	struct list_head work;
> +	struct list_head dead;
>  };
>  
>  /* I hate forward declarations, but I actually have a loop */
> @@ -87,10 +88,12 @@ static void uas_do_work(struct work_struct *work);
>  static int uas_try_complete(struct scsi_cmnd *cmnd, const char *caller);
>  static void uas_configure_endpoints(struct uas_dev_info *devinfo);
>  static void uas_free_streams(struct uas_dev_info *devinfo);
> +static void uas_log_cmd_state(struct scsi_cmnd *cmnd, const char *caller);
>  
>  static DECLARE_WORK(uas_work, uas_do_work);
>  static DEFINE_SPINLOCK(uas_lists_lock);
>  static LIST_HEAD(uas_work_list);
> +static LIST_HEAD(uas_dead_list);
>  
>  static void uas_unlink_data_urbs(struct uas_dev_info *devinfo,
>  				 struct uas_cmd_info *cmdinfo)
> @@ -167,15 +170,13 @@ static void uas_abort_work(struct uas_dev_info *devinfo)
>  		struct uas_dev_info *di = (void *)cmnd->device->hostdata;
>  
>  		if (di == devinfo) {
> +			uas_log_cmd_state(cmnd, __func__);
> +			BUG_ON(cmdinfo->state & COMMAND_ABORTED);
>  			cmdinfo->state |= COMMAND_ABORTED;
> +			spin_lock_irq(&uas_lists_lock);
> +			list_add_tail(&cmdinfo->dead, &uas_dead_list);
> +			spin_unlock_irq(&uas_lists_lock);
>  			cmdinfo->state &= ~IS_IN_WORK_LIST;
> -			if (devinfo->resetting) {
> -				/* uas_stat_cmplt() will not do that
> -				 * when a device reset is in
> -				 * progress */
> -				cmdinfo->state &= ~COMMAND_INFLIGHT;
> -			}
> -			uas_try_complete(cmnd, __func__);
>  		} else {
>  			/* not our uas device, relink into list */
>  			list_del(&cmdinfo->work);
> @@ -187,6 +188,43 @@ static void uas_abort_work(struct uas_dev_info *devinfo)
>  	spin_unlock_irqrestore(&devinfo->lock, flags);
>  }
>  
> +static void uas_zap_dead(struct uas_dev_info *devinfo)
> +{
> +	struct uas_cmd_info *cmdinfo;
> +	struct uas_cmd_info *temp;
> +	struct list_head list;
> +	unsigned long flags;
> +
> +	spin_lock_irq(&uas_lists_lock);
> +	list_replace_init(&uas_dead_list, &list);
> +	spin_unlock_irq(&uas_lists_lock);
> +
> +	spin_lock_irqsave(&devinfo->lock, flags);
> +	list_for_each_entry_safe(cmdinfo, temp, &list, dead) {
> +		struct scsi_pointer *scp = (void *)cmdinfo;
> +		struct scsi_cmnd *cmnd = container_of(scp,
> +							struct scsi_cmnd, SCp);
> +		struct uas_dev_info *di = (void *)cmnd->device->hostdata;
> +
> +		if (di == devinfo) {
> +			uas_log_cmd_state(cmnd, __func__);
> +			BUG_ON(!(cmdinfo->state & COMMAND_ABORTED));
> +			/* all urbs are killed, clear inflight bits */
> +			cmdinfo->state &= ~(COMMAND_INFLIGHT |
> +					    DATA_IN_URB_INFLIGHT |
> +					    DATA_OUT_URB_INFLIGHT);
> +			uas_try_complete(cmnd, __func__);
> +		} else {
> +			/* not our uas device, relink into list */
> +			list_del(&cmdinfo->dead);
> +			spin_lock_irq(&uas_lists_lock);
> +			list_add_tail(&cmdinfo->dead, &uas_dead_list);
> +			spin_unlock_irq(&uas_lists_lock);
> +		}
> +	}
> +	spin_unlock_irqrestore(&devinfo->lock, flags);
> +}
> +
>  static void uas_sense(struct urb *urb, struct scsi_cmnd *cmnd)
>  {
>  	struct sense_iu *sense_iu = urb->transfer_buffer;
> @@ -274,6 +312,9 @@ static int uas_try_complete(struct scsi_cmnd *cmnd, const char *caller)
>  	if (cmdinfo->state & COMMAND_ABORTED) {
>  		scmd_printk(KERN_INFO, cmnd, "abort completed\n");
>  		cmnd->result = DID_ABORT << 16;
> +		spin_lock_irq(&uas_lists_lock);
> +		list_del(&cmdinfo->dead);
> +		spin_unlock_irq(&uas_lists_lock);
>  	}
>  	cmnd->scsi_done(cmnd);
>  	return 0;
> @@ -307,7 +348,12 @@ static void uas_stat_cmplt(struct urb *urb)
>  	u16 tag;
>  
>  	if (urb->status) {
> -		dev_err(&urb->dev->dev, "URB BAD STATUS %d\n", urb->status);
> +		if (urb->status == -ENOENT) {
> +			dev_err(&urb->dev->dev, "stat urb: killed (stream %d\n",
> +				urb->stream_id);
> +		} else {
> +			dev_err(&urb->dev->dev, "stat urb: status %d\n", urb->status);
> +		}
>  		usb_free_urb(urb);
>  		return;
>  	}
> @@ -762,7 +808,11 @@ static int uas_eh_abort_handler(struct scsi_cmnd *cmnd)
>  
>  	uas_log_cmd_state(cmnd, __func__);
>  	spin_lock_irqsave(&devinfo->lock, flags);
> +	BUG_ON(cmdinfo->state & COMMAND_ABORTED);
>  	cmdinfo->state |= COMMAND_ABORTED;
> +	spin_lock_irq(&uas_lists_lock);
> +	list_add_tail(&cmdinfo->dead, &uas_dead_list);
> +	spin_unlock_irq(&uas_lists_lock);
>  	if (cmdinfo->state & IS_IN_WORK_LIST) {
>  		spin_lock(&uas_lists_lock);
>  		list_del(&cmdinfo->work);
> @@ -797,11 +847,13 @@ static int uas_eh_bus_reset_handler(struct scsi_cmnd *cmnd)
>  	struct usb_device *udev = devinfo->udev;
>  	int err;
>  
> +	shost_printk(KERN_INFO, sdev->host, "%s start\n", __func__);
>  	devinfo->resetting = 1;
>  	uas_abort_work(devinfo);
>  	usb_kill_anchored_urbs(&devinfo->cmd_urbs);
>  	usb_kill_anchored_urbs(&devinfo->sense_urbs);
>  	usb_kill_anchored_urbs(&devinfo->data_urbs);
> +	uas_zap_dead(devinfo);
>  	uas_free_streams(devinfo);
>  	err = usb_reset_device(udev);
>  	if (!err) {
> @@ -1055,6 +1107,7 @@ static void uas_disconnect(struct usb_interface *intf)
>  	usb_kill_anchored_urbs(&devinfo->cmd_urbs);
>  	usb_kill_anchored_urbs(&devinfo->sense_urbs);
>  	usb_kill_anchored_urbs(&devinfo->data_urbs);
> +	uas_zap_dead(devinfo);
>  	scsi_remove_host(shost);
>  	uas_free_streams(devinfo);
>  	kfree(devinfo);
> -- 
> 1.8.3.1
> 
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