]> err.no Git - linux-2.6/commitdiff
[PATCH] USB: ub 00 implement retries and resets
authorPete Zaitcev <zaitcev@redhat.com>
Sat, 17 Dec 2005 10:16:43 +0000 (02:16 -0800)
committerGreg Kroah-Hartman <gregkh@suse.de>
Wed, 4 Jan 2006 21:51:43 +0000 (13:51 -0800)
Implement command retries and resets in ub. It is advantageous for users
to know if their devices are getting bad. However, failing every I/O
is not practical if you have a external USB enclosure with a hard drive.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/block/ub.c

index c7a28f5be42fdfe5c4c793308390607fe019d8c2..ba05e31709d50bfbcfa046433e277fc75e847720 100644 (file)
@@ -9,7 +9,6 @@
  *
  * TODO (sorted by decreasing priority)
  *  -- Kill first_open (Al Viro fixed the block layer now)
- *  -- Do resets with usb_device_reset (needs a thread context, use khubd)
  *  -- set readonly flag for CDs, set removable flag for CF readers
  *  -- do inquiry and verify we got a disk and not a tape (for LUN mismatch)
  *  -- special case some senses, e.g. 3a/0 -> no media present, reduce retries
@@ -236,6 +235,13 @@ struct ub_scsi_cmd {
        void *back;
 };
 
+struct ub_request {
+       struct request *rq;
+       unsigned int current_try;
+       unsigned int nsg;               /* sgv[nsg] */
+       struct scatterlist sgv[UB_MAX_REQ_SG];
+};
+
 /*
  */
 struct ub_capacity {
@@ -331,6 +337,8 @@ struct ub_lun {
        int readonly;
        int first_open;                 /* Kludge. See ub_bd_open. */
 
+       struct ub_request urq;
+
        /* Use Ingo's mempool if or when we have more than one command. */
        /*
         * Currently we never need more than one command for the whole device.
@@ -351,6 +359,7 @@ struct ub_dev {
        atomic_t poison;                /* The USB device is disconnected */
        int openc;                      /* protected by ub_lock! */
                                        /* kref is too implicit for our taste */
+       int reset;                      /* Reset is running */
        unsigned int tagcnt;
        char name[12];
        struct usb_device *dev;
@@ -378,6 +387,9 @@ struct ub_dev {
        struct bulk_cs_wrap work_bcs;
        struct usb_ctrlrequest work_cr;
 
+       struct work_struct reset_work;
+       wait_queue_head_t reset_wait;
+
        int sg_stat[6];
        struct ub_scsi_trace tr;
 };
@@ -386,12 +398,14 @@ struct ub_dev {
  */
 static void ub_cleanup(struct ub_dev *sc);
 static int ub_request_fn_1(struct ub_lun *lun, struct request *rq);
-static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
-    struct ub_scsi_cmd *cmd, struct request *rq);
-static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
-    struct ub_scsi_cmd *cmd, struct request *rq);
+static void ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
+    struct ub_scsi_cmd *cmd, struct ub_request *urq);
+static void ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
+    struct ub_scsi_cmd *cmd, struct ub_request *urq);
 static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 static void ub_end_rq(struct request *rq, int uptodate);
+static int ub_rw_cmd_retry(struct ub_dev *sc, struct ub_lun *lun,
+    struct ub_request *urq, struct ub_scsi_cmd *cmd);
 static int ub_submit_scsi(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 static void ub_urb_complete(struct urb *urb, struct pt_regs *pt);
 static void ub_scsi_action(unsigned long _dev);
@@ -406,6 +420,8 @@ static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
 static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
     int stalled_pipe);
 static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd);
+static void ub_reset_enter(struct ub_dev *sc);
+static void ub_reset_task(void *arg);
 static int ub_sync_tur(struct ub_dev *sc, struct ub_lun *lun);
 static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
     struct ub_capacity *ret);
@@ -517,6 +533,9 @@ static ssize_t ub_diag_show(struct device *dev, struct device_attribute *attr,
        cnt = 0;
        spin_lock_irqsave(&sc->lock, flags);
 
+       cnt += sprintf(page + cnt,
+           "poison %d reset %d\n",
+           atomic_read(&sc->poison), sc->reset);
        cnt += sprintf(page + cnt,
            "qlen %d qmax %d\n",
            sc->cmd_queue.qlen, sc->cmd_queue.qmax);
@@ -766,7 +785,8 @@ static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
 {
        struct ub_dev *sc = lun->udev;
        struct ub_scsi_cmd *cmd;
-       int rc;
+       struct ub_request *urq;
+       int n_elem;
 
        if (atomic_read(&sc->poison) || lun->changed) {
                blkdev_dequeue_request(rq);
@@ -774,65 +794,70 @@ static int ub_request_fn_1(struct ub_lun *lun, struct request *rq)
                return 0;
        }
 
+       if (lun->urq.rq != NULL)
+               return -1;
        if ((cmd = ub_get_cmd(lun)) == NULL)
                return -1;
        memset(cmd, 0, sizeof(struct ub_scsi_cmd));
 
        blkdev_dequeue_request(rq);
+
+       urq = &lun->urq;
+       memset(urq, 0, sizeof(struct ub_request));
+       urq->rq = rq;
+
+       /*
+        * get scatterlist from block layer
+        */
+       n_elem = blk_rq_map_sg(lun->disk->queue, rq, &urq->sgv[0]);
+       if (n_elem < 0) {
+               printk(KERN_INFO "%s: failed request map (%d)\n",
+                   lun->name, n_elem); /* P3 */
+               goto drop;
+       }
+       if (n_elem > UB_MAX_REQ_SG) {   /* Paranoia */
+               printk(KERN_WARNING "%s: request with %d segments\n",
+                   lun->name, n_elem);
+               goto drop;
+       }
+       urq->nsg = n_elem;
+       sc->sg_stat[n_elem < 5 ? n_elem : 5]++;
+
        if (blk_pc_request(rq)) {
-               rc = ub_cmd_build_packet(sc, lun, cmd, rq);
+               ub_cmd_build_packet(sc, lun, cmd, urq);
        } else {
-               rc = ub_cmd_build_block(sc, lun, cmd, rq);
-       }
-       if (rc != 0) {
-               ub_put_cmd(lun, cmd);
-               ub_end_rq(rq, 0);
-               return 0;
+               ub_cmd_build_block(sc, lun, cmd, urq);
        }
        cmd->state = UB_CMDST_INIT;
        cmd->lun = lun;
        cmd->done = ub_rw_cmd_done;
-       cmd->back = rq;
+       cmd->back = urq;
 
        cmd->tag = sc->tagcnt++;
-       if (ub_submit_scsi(sc, cmd) != 0) {
-               ub_put_cmd(lun, cmd);
-               ub_end_rq(rq, 0);
-               return 0;
-       }
+       if (ub_submit_scsi(sc, cmd) != 0)
+               goto drop;
+
+       return 0;
 
+drop:
+       ub_put_cmd(lun, cmd);
+       ub_end_rq(rq, 0);
        return 0;
 }
 
-static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
-    struct ub_scsi_cmd *cmd, struct request *rq)
+static void ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
+    struct ub_scsi_cmd *cmd, struct ub_request *urq)
 {
-       int ub_dir;
-       int n_elem;
+       struct request *rq = urq->rq;
        unsigned int block, nblks;
 
        if (rq_data_dir(rq) == WRITE)
-               ub_dir = UB_DIR_WRITE;
+               cmd->dir = UB_DIR_WRITE;
        else
-               ub_dir = UB_DIR_READ;
-       cmd->dir = ub_dir;
+               cmd->dir = UB_DIR_READ;
 
-       /*
-        * get scatterlist from block layer
-        */
-       n_elem = blk_rq_map_sg(lun->disk->queue, rq, &cmd->sgv[0]);
-       if (n_elem <= 0) {
-               printk(KERN_INFO "%s: failed request map (%d)\n",
-                   sc->name, n_elem); /* P3 */
-               return -1;              /* request with no s/g entries? */
-       }
-       if (n_elem > UB_MAX_REQ_SG) {   /* Paranoia */
-               printk(KERN_WARNING "%s: request with %d segments\n",
-                   sc->name, n_elem);
-               return -1;
-       }
-       cmd->nsg = n_elem;
-       sc->sg_stat[n_elem < 5 ? n_elem : 5]++;
+       cmd->nsg = urq->nsg;
+       memcpy(cmd->sgv, urq->sgv, sizeof(struct scatterlist) * cmd->nsg);
 
        /*
         * build the command
@@ -843,7 +868,7 @@ static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
        block = rq->sector >> lun->capacity.bshift;
        nblks = rq->nr_sectors >> lun->capacity.bshift;
 
-       cmd->cdb[0] = (ub_dir == UB_DIR_READ)? READ_10: WRITE_10;
+       cmd->cdb[0] = (cmd->dir == UB_DIR_READ)? READ_10: WRITE_10;
        /* 10-byte uses 4 bytes of LBA: 2147483648KB, 2097152MB, 2048GB */
        cmd->cdb[2] = block >> 24;
        cmd->cdb[3] = block >> 16;
@@ -854,14 +879,12 @@ static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
        cmd->cdb_len = 10;
 
        cmd->len = rq->nr_sectors * 512;
-
-       return 0;
 }
 
-static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
-    struct ub_scsi_cmd *cmd, struct request *rq)
+static void ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
+    struct ub_scsi_cmd *cmd, struct ub_request *urq)
 {
-       int n_elem;
+       struct request *rq = urq->rq;
 
        if (rq->data_len == 0) {
                cmd->dir = UB_DIR_NONE;
@@ -870,40 +893,26 @@ static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
                        cmd->dir = UB_DIR_WRITE;
                else
                        cmd->dir = UB_DIR_READ;
-
        }
 
-       /*
-        * get scatterlist from block layer
-        */
-       n_elem = blk_rq_map_sg(lun->disk->queue, rq, &cmd->sgv[0]);
-       if (n_elem < 0) {
-               printk(KERN_INFO "%s: failed request map (%d)\n",
-                   sc->name, n_elem); /* P3 */
-               return -1;
-       }
-       if (n_elem > UB_MAX_REQ_SG) {   /* Paranoia */
-               printk(KERN_WARNING "%s: request with %d segments\n",
-                   sc->name, n_elem);
-               return -1;
-       }
-       cmd->nsg = n_elem;
-       sc->sg_stat[n_elem < 5 ? n_elem : 5]++;
+       cmd->nsg = urq->nsg;
+       memcpy(cmd->sgv, urq->sgv, sizeof(struct scatterlist) * cmd->nsg);
 
        memcpy(&cmd->cdb, rq->cmd, rq->cmd_len);
        cmd->cdb_len = rq->cmd_len;
 
        cmd->len = rq->data_len;
-
-       return 0;
 }
 
 static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 {
-       struct request *rq = cmd->back;
        struct ub_lun *lun = cmd->lun;
+       struct ub_request *urq = cmd->back;
+       struct request *rq;
        int uptodate;
 
+       rq = urq->rq;
+
        if (cmd->error == 0) {
                uptodate = 1;
 
@@ -924,9 +933,16 @@ static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                                rq->errors = SAM_STAT_CHECK_CONDITION;
                        else
                                rq->errors = DID_ERROR << 16;
+               } else {
+                       if (cmd->error == -EIO) {
+                               if (ub_rw_cmd_retry(sc, lun, urq, cmd) == 0)
+                                       return;
+                       }
                }
        }
 
+       urq->rq = NULL;
+
        ub_put_cmd(lun, cmd);
        ub_end_rq(rq, uptodate);
        blk_start_queue(lun->disk->queue);
@@ -941,6 +957,41 @@ static void ub_end_rq(struct request *rq, int uptodate)
        end_that_request_last(rq);
 }
 
+static int ub_rw_cmd_retry(struct ub_dev *sc, struct ub_lun *lun,
+    struct ub_request *urq, struct ub_scsi_cmd *cmd)
+{
+
+       if (atomic_read(&sc->poison))
+               return -ENXIO;
+
+       ub_reset_enter(sc);
+
+       if (urq->current_try >= 3)
+               return -EIO;
+       urq->current_try++;
+       /* P3 */ printk("%s: dir %c len/act %d/%d "
+           "[sense %x %02x %02x] retry %d\n",
+           sc->name, UB_DIR_CHAR(cmd->dir), cmd->len, cmd->act_len,
+           cmd->key, cmd->asc, cmd->ascq, urq->current_try);
+
+       memset(cmd, 0, sizeof(struct ub_scsi_cmd));
+       ub_cmd_build_block(sc, lun, cmd, urq);
+
+       cmd->state = UB_CMDST_INIT;
+       cmd->lun = lun;
+       cmd->done = ub_rw_cmd_done;
+       cmd->back = urq;
+
+       cmd->tag = sc->tagcnt++;
+
+#if 0 /* Wasteful */
+       return ub_submit_scsi(sc, cmd);
+#else
+       ub_cmdq_add(sc, cmd);
+       return 0;
+#endif
+}
+
 /*
  * Submit a regular SCSI operation (not an auto-sense).
  *
@@ -1071,7 +1122,7 @@ static void ub_scsi_dispatch(struct ub_dev *sc)
        struct ub_scsi_cmd *cmd;
        int rc;
 
-       while ((cmd = ub_cmdq_peek(sc)) != NULL) {
+       while (!sc->reset && (cmd = ub_cmdq_peek(sc)) != NULL) {
                if (cmd->state == UB_CMDST_DONE) {
                        ub_cmdq_pop(sc);
                        (*cmd->done)(sc, cmd);
@@ -1094,11 +1145,12 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 {
        struct urb *urb = &sc->work_urb;
        struct bulk_cs_wrap *bcs;
+       int len;
        int rc;
 
        if (atomic_read(&sc->poison)) {
-               /* A little too simplistic, I feel... */
-               goto Bad_End;
+               ub_state_done(sc, cmd, -ENODEV);
+               return;
        }
 
        if (cmd->state == UB_CMDST_CLEAR) {
@@ -1106,7 +1158,6 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                        /*
                         * STALL while clearning STALL.
                         * The control pipe clears itself - nothing to do.
-                        * XXX Might try to reset the device here and retry.
                         */
                        printk(KERN_NOTICE "%s: stall on control pipe\n",
                            sc->name);
@@ -1125,11 +1176,6 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 
        } else if (cmd->state == UB_CMDST_CLR2STS) {
                if (urb->status == -EPIPE) {
-                       /*
-                        * STALL while clearning STALL.
-                        * The control pipe clears itself - nothing to do.
-                        * XXX Might try to reset the device here and retry.
-                        */
                        printk(KERN_NOTICE "%s: stall on control pipe\n",
                            sc->name);
                        goto Bad_End;
@@ -1147,11 +1193,6 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
 
        } else if (cmd->state == UB_CMDST_CLRRS) {
                if (urb->status == -EPIPE) {
-                       /*
-                        * STALL while clearning STALL.
-                        * The control pipe clears itself - nothing to do.
-                        * XXX Might try to reset the device here and retry.
-                        */
                        printk(KERN_NOTICE "%s: stall on control pipe\n",
                            sc->name);
                        goto Bad_End;
@@ -1168,7 +1209,12 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                ub_state_stat_counted(sc, cmd);
 
        } else if (cmd->state == UB_CMDST_CMD) {
-               if (urb->status == -EPIPE) {
+               switch (urb->status) {
+               case 0:
+                       break;
+               case -EOVERFLOW:
+                       goto Bad_End;
+               case -EPIPE:
                        rc = ub_submit_clear_stall(sc, cmd, sc->last_pipe);
                        if (rc != 0) {
                                printk(KERN_NOTICE "%s: "
@@ -1178,17 +1224,20 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                                 * This is typically ENOMEM or some other such shit.
                                 * Retrying is pointless. Just do Bad End on it...
                                 */
-                               goto Bad_End;
+                               ub_state_done(sc, cmd, rc);
+                               return;
                        }
                        cmd->state = UB_CMDST_CLEAR;
                        ub_cmdtr_state(sc, cmd);
                        return;
-               }
-               if (urb->status != 0) {
+               case -ESHUTDOWN:        /* unplug */
+               case -EILSEQ:           /* unplug timeout on uhci */
+                       ub_state_done(sc, cmd, -ENODEV);
+                       return;
+               default:
                        goto Bad_End;
                }
                if (urb->actual_length != US_BULK_CB_WRAP_LEN) {
-                       /* XXX Must do reset here to unconfuse the device */
                        goto Bad_End;
                }
 
@@ -1207,11 +1256,8 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                                printk(KERN_NOTICE "%s: "
                                    "unable to submit clear (%d)\n",
                                    sc->name, rc);
-                               /*
-                                * This is typically ENOMEM or some other such shit.
-                                * Retrying is pointless. Just do Bad End on it...
-                                */
-                               goto Bad_End;
+                               ub_state_done(sc, cmd, rc);
+                               return;
                        }
                        cmd->state = UB_CMDST_CLR2STS;
                        ub_cmdtr_state(sc, cmd);
@@ -1220,14 +1266,50 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                if (urb->status == -EOVERFLOW) {
                        /*
                         * A babble? Failure, but we must transfer CSW now.
-                        * XXX This is going to end in perpetual babble. Reset.
                         */
                        cmd->error = -EOVERFLOW;        /* A cheap trick... */
                        ub_state_stat(sc, cmd);
                        return;
                }
-               if (urb->status != 0)
-                       goto Bad_End;
+
+               if (cmd->dir == UB_DIR_WRITE) {
+                       /*
+                        * Do not continue writes in case of a failure.
+                        * Doing so would cause sectors to be mixed up,
+                        * which is worse than sectors lost.
+                        *
+                        * We must try to read the CSW, or many devices
+                        * get confused.
+                        */
+                       len = urb->actual_length;
+                       if (urb->status != 0 ||
+                           len != cmd->sgv[cmd->current_sg].length) {
+                               cmd->act_len += len;
+                               ub_cmdtr_act_len(sc, cmd);
+
+                               cmd->error = -EIO;
+                               ub_state_stat(sc, cmd);
+                               return;
+                       }
+
+               } else {
+                       /*
+                        * If an error occurs on read, we record it, and
+                        * continue to fetch data in order to avoid bubble.
+                        *
+                        * As a small shortcut, we stop if we detect that
+                        * a CSW mixed into data.
+                        */
+                       if (urb->status != 0)
+                               cmd->error = -EIO;
+
+                       len = urb->actual_length;
+                       if (urb->status != 0 ||
+                           len != cmd->sgv[cmd->current_sg].length) {
+                               if ((len & 0x1FF) == US_BULK_CS_WRAP_LEN)
+                                       goto Bad_End;
+                       }
+               }
 
                cmd->act_len += urb->actual_length;
                ub_cmdtr_act_len(sc, cmd);
@@ -1245,11 +1327,8 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                                printk(KERN_NOTICE "%s: "
                                    "unable to submit clear (%d)\n",
                                    sc->name, rc);
-                               /*
-                                * This is typically ENOMEM or some other such shit.
-                                * Retrying is pointless. Just do Bad End on it...
-                                */
-                               goto Bad_End;
+                               ub_state_done(sc, cmd, rc);
+                               return;
                        }
 
                        /*
@@ -1262,14 +1341,8 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                        ub_cmdtr_state(sc, cmd);
                        return;
                }
-               if (urb->status == -EOVERFLOW) {
-                       /*
-                        * XXX We are screwed here. Retrying is pointless,
-                        * because the pipelined data will not get in until
-                        * we read with a big enough buffer. We must reset XXX.
-                        */
-                       goto Bad_End;
-               }
+
+               /* Catch everything, including -EOVERFLOW and other nasties. */
                if (urb->status != 0)
                        goto Bad_End;
 
@@ -1315,15 +1388,15 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                        return;
                }
 
-               rc = le32_to_cpu(bcs->Residue);
-               if (rc != cmd->len - cmd->act_len) {
+               len = le32_to_cpu(bcs->Residue);
+               if (len != cmd->len - cmd->act_len) {
                        /*
                         * It is all right to transfer less, the caller has
                         * to check. But it's not all right if the device
                         * counts disagree with our counts.
                         */
                        /* P3 */ printk("%s: resid %d len %d act %d\n",
-                           sc->name, rc, cmd->len, cmd->act_len);
+                           sc->name, len, cmd->len, cmd->act_len);
                        goto Bad_End;
                }
 
@@ -1334,13 +1407,13 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                        ub_state_sense(sc, cmd);
                        return;
                case US_BULK_STAT_PHASE:
-                       /* XXX We must reset the transport here */
                        /* P3 */ printk("%s: status PHASE\n", sc->name);
                        goto Bad_End;
                default:
                        printk(KERN_INFO "%s: unknown CSW status 0x%x\n",
                            sc->name, bcs->Status);
-                       goto Bad_End;
+                       ub_state_done(sc, cmd, -EINVAL);
+                       return;
                }
 
                /* Not zeroing error to preserve a babble indicator */
@@ -1360,7 +1433,8 @@ static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
                printk(KERN_WARNING "%s: "
                    "wrong command state %d\n",
                    sc->name, cmd->state);
-               goto Bad_End;
+               ub_state_done(sc, cmd, -EINVAL);
+               return;
        }
        return;
 
@@ -1607,6 +1681,93 @@ static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd)
        ub_scsi_urb_compl(sc, cmd);
 }
 
+/*
+ * Reset management
+ */
+
+static void ub_reset_enter(struct ub_dev *sc)
+{
+
+       if (sc->reset) {
+               /* This happens often on multi-LUN devices. */
+               return;
+       }
+       sc->reset = 1;
+
+#if 0 /* Not needed because the disconnect waits for us. */
+       unsigned long flags;
+       spin_lock_irqsave(&ub_lock, flags);
+       sc->openc++;
+       spin_unlock_irqrestore(&ub_lock, flags);
+#endif
+
+#if 0 /* We let them stop themselves. */
+       struct list_head *p;
+       struct ub_lun *lun;
+       list_for_each(p, &sc->luns) {
+               lun = list_entry(p, struct ub_lun, link);
+               blk_stop_queue(lun->disk->queue);
+       }
+#endif
+
+       schedule_work(&sc->reset_work);
+}
+
+static void ub_reset_task(void *arg)
+{
+       struct ub_dev *sc = arg;
+       unsigned long flags;
+       struct list_head *p;
+       struct ub_lun *lun;
+       int lkr, rc;
+
+       if (!sc->reset) {
+               printk(KERN_WARNING "%s: Running reset unrequested\n",
+                   sc->name);
+               return;
+       }
+
+       if (atomic_read(&sc->poison)) {
+               printk(KERN_NOTICE "%s: Not resetting disconnected device\n",
+                   sc->name); /* P3 This floods. Remove soon. XXX */
+       } else if (sc->dev->actconfig->desc.bNumInterfaces != 1) {
+               printk(KERN_NOTICE "%s: Not resetting multi-interface device\n",
+                   sc->name); /* P3 This floods. Remove soon. XXX */
+       } else {
+               if ((lkr = usb_lock_device_for_reset(sc->dev, sc->intf)) < 0) {
+                       printk(KERN_NOTICE
+                           "%s: usb_lock_device_for_reset failed (%d)\n",
+                           sc->name, lkr);
+               } else {
+                       rc = usb_reset_device(sc->dev);
+                       if (rc < 0) {
+                               printk(KERN_NOTICE "%s: "
+                                   "usb_lock_device_for_reset failed (%d)\n",
+                                   sc->name, rc);
+                       }
+
+                       if (lkr)
+                               usb_unlock_device(sc->dev);
+               }
+       }
+
+       /*
+        * In theory, no commands can be running while reset is active,
+        * so nobody can ask for another reset, and so we do not need any
+        * queues of resets or anything. We do need a spinlock though,
+        * to interact with block layer.
+        */
+       spin_lock_irqsave(&sc->lock, flags);
+       sc->reset = 0;
+       tasklet_schedule(&sc->tasklet);
+       list_for_each(p, &sc->luns) {
+               lun = list_entry(p, struct ub_lun, link);
+               blk_start_queue(lun->disk->queue);
+       }
+       wake_up(&sc->reset_wait);
+       spin_unlock_irqrestore(&sc->lock, flags);
+}
+
 /*
  * This is called from a process context.
  */
@@ -2142,7 +2303,7 @@ static int ub_get_pipes(struct ub_dev *sc, struct usb_device *dev,
        if (ep_in == NULL || ep_out == NULL) {
                printk(KERN_NOTICE "%s: failed endpoint check\n",
                    sc->name);
-               return -EIO;
+               return -ENODEV;
        }
 
        /* Calculate and store the pipe values */
@@ -2180,6 +2341,8 @@ static int ub_probe(struct usb_interface *intf,
        usb_init_urb(&sc->work_urb);
        tasklet_init(&sc->tasklet, ub_scsi_action, (unsigned long)sc);
        atomic_set(&sc->poison, 0);
+       INIT_WORK(&sc->reset_work, ub_reset_task, sc);
+       init_waitqueue_head(&sc->reset_wait);
 
        init_timer(&sc->work_timer);
        sc->work_timer.data = (unsigned long) sc;
@@ -2200,7 +2363,8 @@ static int ub_probe(struct usb_interface *intf,
 
        /* XXX Verify that we can handle the device (from descriptors) */
 
-       ub_get_pipes(sc, sc->dev, intf);
+       if (ub_get_pipes(sc, sc->dev, intf) != 0)
+               goto err_dev_desc;
 
        if (device_create_file(&sc->intf->dev, &dev_attr_diag) != 0)
                goto err_diag;
@@ -2271,6 +2435,7 @@ static int ub_probe(struct usb_interface *intf,
 
        /* device_remove_file(&sc->intf->dev, &dev_attr_diag); */
 err_diag:
+err_dev_desc:
        usb_set_intfdata(intf, NULL);
        // usb_put_intf(sc->intf);
        usb_put_dev(sc->dev);
@@ -2378,6 +2543,11 @@ static void ub_disconnect(struct usb_interface *intf)
         */
        atomic_set(&sc->poison, 1);
 
+       /*
+        * Wait for reset to end, if any.
+        */
+       wait_event(sc->reset_wait, !sc->reset);
+
        /*
         * Blow away queued commands.
         *
@@ -2391,7 +2561,7 @@ static void ub_disconnect(struct usb_interface *intf)
        {
                struct ub_scsi_cmd *cmd;
                int cnt = 0;
-               while ((cmd = ub_cmdq_pop(sc)) != NULL) {
+               while ((cmd = ub_cmdq_peek(sc)) != NULL) {
                        cmd->error = -ENOTCONN;
                        cmd->state = UB_CMDST_DONE;
                        ub_cmdtr_state(sc, cmd);