src/patches/suse-2.6.27.31/patches.arch/s390-10-09-dasd-fix-timer-add.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: dasd: fix race in dasd timer handling
   3 References: bnc#482818,LTC#52092
   4
   5 Symptom:     DASD driver runs into BUG statement in add_timer
   6 Problem:     If the timer expires just after we check whether it is
   7              still pending and before mod_timer is called, then
   8              mod_timer will setup the timer, return zero and add_timer
   9              will be called as well although the timer is already set.
  10 Solution:    Initialize the timer variables at device creation time
  11              and remove all timer_pending checks from dasd functions.
  12              del_timer and mod_timer will do all the necessary
  13              checking themselves and mod_timer will set a timer if it
  14              is not already pending.
  15
  16 Acked-by: John Jolly <jjolly@suse.de>
  17 ---
  18  drivers/s390/block/dasd.c |   46 ++++++++++++++++------------------------------
  19  1 file changed, 16 insertions(+), 30 deletions(-)
  20
  21 Index: linux-sles11/drivers/s390/block/dasd.c
  22 ===================================================================
  23 --- linux-sles11.orig/drivers/s390/block/dasd.c
  24 +++ linux-sles11/drivers/s390/block/dasd.c
  25 @@ -57,6 +57,8 @@ static void dasd_device_tasklet(struct d
  26  static void dasd_block_tasklet(struct dasd_block *);
  27  static void do_kick_device(struct work_struct *);
  28  static void dasd_return_cqr_cb(struct dasd_ccw_req *, void *);
  29 +static void dasd_device_timeout(unsigned long);
  30 +static void dasd_block_timeout(unsigned long);
  31
  32  /*
  33   * SECTION: Operations on the device structure.
  34 @@ -99,6 +101,8 @@ struct dasd_device *dasd_alloc_device(vo
  35                      (unsigned long) device);
  36         INIT_LIST_HEAD(&device->ccw_queue);
  37         init_timer(&device->timer);
  38 +       device->timer.function = dasd_device_timeout;
  39 +       device->timer.data = (unsigned long) device;
  40         INIT_WORK(&device->kick_work, do_kick_device);
  41         device->state = DASD_STATE_NEW;
  42         device->target = DASD_STATE_NEW;
  43 @@ -138,6 +142,8 @@ struct dasd_block *dasd_alloc_block(void
  44         INIT_LIST_HEAD(&block->ccw_queue);
  45         spin_lock_init(&block->queue_lock);
  46         init_timer(&block->timer);
  47 +       block->timer.function = dasd_block_timeout;
  48 +       block->timer.data = (unsigned long) block;
  49
  50         return block;
  51  }
  52 @@ -923,19 +929,10 @@ static void dasd_device_timeout(unsigned
  53   */
  54  void dasd_device_set_timer(struct dasd_device *device, int expires)
  55  {
  56 -       if (expires == 0) {
  57 -               if (timer_pending(&device->timer))
  58 -                       del_timer(&device->timer);
  59 -               return;
  60 -       }
  61 -       if (timer_pending(&device->timer)) {
  62 -               if (mod_timer(&device->timer, jiffies + expires))
  63 -                       return;
  64 -       }
  65 -       device->timer.function = dasd_device_timeout;
  66 -       device->timer.data = (unsigned long) device;
  67 -       device->timer.expires = jiffies + expires;
  68 -       add_timer(&device->timer);
  69 +       if (expires == 0)
  70 +               del_timer(&device->timer);
  71 +       else
  72 +               mod_timer(&device->timer, jiffies + expires);
  73  }
  74
  75  /*
  76 @@ -943,8 +940,7 @@ void dasd_device_set_timer(struct dasd_d
  77   */
  78  void dasd_device_clear_timer(struct dasd_device *device)
  79  {
  80 -       if (timer_pending(&device->timer))
  81 -               del_timer(&device->timer);
  82 +       del_timer(&device->timer);
  83  }
  84
  85  static void dasd_handle_killed_request(struct ccw_device *cdev,
  86 @@ -1594,19 +1590,10 @@ static void dasd_block_timeout(unsigned
  87   */
  88  void dasd_block_set_timer(struct dasd_block *block, int expires)
  89  {
  90 -       if (expires == 0) {
  91 -               if (timer_pending(&block->timer))
  92 -                       del_timer(&block->timer);
  93 -               return;
  94 -       }
  95 -       if (timer_pending(&block->timer)) {
  96 -               if (mod_timer(&block->timer, jiffies + expires))
  97 -                       return;
  98 -       }
  99 -       block->timer.function = dasd_block_timeout;
 100 -       block->timer.data = (unsigned long) block;
 101 -       block->timer.expires = jiffies + expires;
 102 -       add_timer(&block->timer);
 103 +       if (expires == 0)
 104 +               del_timer(&block->timer);
 105 +       else
 106 +               mod_timer(&block->timer, jiffies + expires);
 107  }
 108
 109  /*
 110 @@ -1614,8 +1601,7 @@ void dasd_block_set_timer(struct dasd_bl
 111   */
 112  void dasd_block_clear_timer(struct dasd_block *block)
 113  {
 114 -       if (timer_pending(&block->timer))
 115 -               del_timer(&block->timer);
 116 +       del_timer(&block->timer);
 117  }
 118
 119  /*