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

Sarah Sharp
2013-09-03T17:39:08Z

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@redhat.com>
> ---
> 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
>