src/patches/suse-2.6.27.31/patches.arch/s390-02-09-tape-lock.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: tape device driver: improve locking
   3 References: bnc#434333
   4
   5 Symptom:     1. message "Badness at include/linux/blkdev.h"
   6              2. lockdep message "INFO: inconsistent lock state"
   7 Problem:     1. Tape block device driver does not hold request queue lock
   8                 when completing request via __blk_end_request.
   9              2. During open() processing tape device driver receives
  10                 interrupt while holding the tape device lock.
  11 Solution:    1. Use blk_end_request rather than __blk_end_request
  12              2. Use spin_lock_irq to disable interrupts rather than spin_lock.
  13
  14 Acked-by: John Jolly <jjolly@suse.de>
  15 ---
  16  drivers/s390/char/tape_block.c |    6 ++++--
  17  drivers/s390/char/tape_core.c  |    8 ++++----
  18  2 files changed, 8 insertions(+), 6 deletions(-)
  19
  20 Index: temp_orig/drivers/s390/char/tape_block.c
  21 ===================================================================
  22 --- temp_orig.orig/drivers/s390/char/tape_block.c
  23 +++ temp_orig/drivers/s390/char/tape_block.c
  24 @@ -76,7 +76,7 @@ tapeblock_trigger_requeue(struct tape_de
  25  static void
  26  tapeblock_end_request(struct request *req, int error)
  27  {
  28 -       if (__blk_end_request(req, error, blk_rq_bytes(req)))
  29 +       if (blk_end_request(req, error, blk_rq_bytes(req)))
  30                 BUG();
  31  }
  32
  33 @@ -166,7 +166,7 @@ tapeblock_requeue(struct work_struct *wo
  34                 nr_queued++;
  35         spin_unlock(get_ccwdev_lock(device->cdev));
  36
  37 -       spin_lock(&device->blk_data.request_queue_lock);
  38 +       spin_lock_irq(&device->blk_data.request_queue_lock);
  39         while (
  40                 !blk_queue_plugged(queue) &&
  41                 elv_next_request(queue)   &&
  42 @@ -176,7 +176,9 @@ tapeblock_requeue(struct work_struct *wo
  43                 if (rq_data_dir(req) == WRITE) {
  44                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
  45                         blkdev_dequeue_request(req);
  46 +                       spin_unlock_irq(&device->blk_data.request_queue_lock);
  47                         tapeblock_end_request(req, -EIO);
  48 +                       spin_lock_irq(&device->blk_data.request_queue_lock);
  49                         continue;
  50                 }
  51                 blkdev_dequeue_request(req);
  52 Index: temp_orig/drivers/s390/char/tape_core.c
  53 ===================================================================
  54 --- temp_orig.orig/drivers/s390/char/tape_core.c
  55 +++ temp_orig/drivers/s390/char/tape_core.c
  56 @@ -1199,7 +1199,7 @@ tape_open(struct tape_device *device)
  57  {
  58         int rc;
  59
  60 -       spin_lock(get_ccwdev_lock(device->cdev));
  61 +       spin_lock_irq(get_ccwdev_lock(device->cdev));
  62         if (device->tape_state == TS_NOT_OPER) {
  63                 DBF_EVENT(6, "TAPE:nodev\n");
  64                 rc = -ENODEV;
  65 @@ -1217,7 +1217,7 @@ tape_open(struct tape_device *device)
  66                 tape_state_set(device, TS_IN_USE);
  67                 rc = 0;
  68         }
  69 -       spin_unlock(get_ccwdev_lock(device->cdev));
  70 +       spin_unlock_irq(get_ccwdev_lock(device->cdev));
  71         return rc;
  72  }
  73
  74 @@ -1227,11 +1227,11 @@ tape_open(struct tape_device *device)
  75  int
  76  tape_release(struct tape_device *device)
  77  {
  78 -       spin_lock(get_ccwdev_lock(device->cdev));
  79 +       spin_lock_irq(get_ccwdev_lock(device->cdev));
  80         if (device->tape_state == TS_IN_USE)
  81                 tape_state_set(device, TS_UNUSED);
  82         module_put(device->discipline->owner);
  83 -       spin_unlock(get_ccwdev_lock(device->cdev));
  84 +       spin_unlock_irq(get_ccwdev_lock(device->cdev));
  85         return 0;
  86  }
  87