src/patches/suse-2.6.27.31/patches.arch/s390-11-07-qdio_kill_tasklets.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: qdio: proper kill of qdio tasklets
   3 References: bnc#484767,LTC#52206
   4
   5 Symptom:     kernel BUG at kernel/softirq.c:392!
   6 Problem:     The queue tasklets were stopped with tasklet_disable. Although
   7              tasklet_disable prevents the tasklet from beeing executed it is
   8              still possible that a tasklet is scheduled on a CPU at that point.
   9              A following qdio_establish calls tasklet_init which clears the
  10              tasklet count and the tasklet state leading to the oops.
  11 Solution:    Use tasklet_kill instead of tasklet_disbale. Since
  12              tasklet_schedule must not be called after tasklet_kill use the
  13              QDIO_IRQ_STATE_STOPPED to inidicate that a queue is going down
  14              and prevent further tasklet schedules in that case.
  15
  16 Acked-by: John Jolly <jjolly@suse.de>
  17 ---
  18  drivers/s390/cio/qdio_main.c    |   35 ++++++++++++++++++++++++-----------
  19  drivers/s390/cio/qdio_thinint.c |    8 ++++----
  20  2 files changed, 28 insertions(+), 15 deletions(-)
  21
  22 Index: linux-sles11/drivers/s390/cio/qdio_main.c
  23 ===================================================================
  24 --- linux-sles11.orig/drivers/s390/cio/qdio_main.c
  25 +++ linux-sles11/drivers/s390/cio/qdio_main.c
  26 @@ -760,21 +760,17 @@ static void __qdio_outbound_processing(s
  27         if (qdio_outbound_q_moved(q))
  28                 qdio_kick_outbound_handler(q);
  29
  30 -       if (queue_type(q) == QDIO_ZFCP_QFMT) {
  31 +       if (queue_type(q) == QDIO_ZFCP_QFMT)
  32                 if (!pci_out_supported(q) && !qdio_outbound_q_done(q))
  33 -                       tasklet_schedule(&q->tasklet);
  34 -               return;
  35 -       }
  36 +                       goto sched;
  37
  38         /* bail out for HiperSockets unicast queues */
  39         if (queue_type(q) == QDIO_IQDIO_QFMT && !multicast_outbound(q))
  40                 return;
  41
  42         if ((queue_type(q) == QDIO_IQDIO_QFMT) &&
  43 -           (atomic_read(&q->nr_buf_used)) > QDIO_IQDIO_POLL_LVL) {
  44 -               tasklet_schedule(&q->tasklet);
  45 -               return;
  46 -       }
  47 +           (atomic_read(&q->nr_buf_used)) > QDIO_IQDIO_POLL_LVL)
  48 +               goto sched;
  49
  50         if (q->u.out.pci_out_enabled)
  51                 return;
  52 @@ -792,6 +788,12 @@ static void __qdio_outbound_processing(s
  53                         qdio_perf_stat_inc(&perf_stats.debug_tl_out_timer);
  54                 }
  55         }
  56 +       return;
  57 +
  58 +sched:
  59 +       if (unlikely(q->irq_ptr->state == QDIO_IRQ_STATE_STOPPED))
  60 +               return;
  61 +       tasklet_schedule(&q->tasklet);
  62  }
  63
  64  /* outbound tasklet */
  65 @@ -804,6 +806,9 @@ void qdio_outbound_processing(unsigned l
  66  void qdio_outbound_timer(unsigned long data)
  67  {
  68         struct qdio_q *q = (struct qdio_q *)data;
  69 +
  70 +       if (unlikely(q->irq_ptr->state == QDIO_IRQ_STATE_STOPPED))
  71 +               return;
  72         tasklet_schedule(&q->tasklet);
  73  }
  74
  75 @@ -845,6 +850,9 @@ static void qdio_int_handler_pci(struct
  76         int i;
  77         struct qdio_q *q;
  78
  79 +       if (unlikely(irq_ptr->state == QDIO_IRQ_STATE_STOPPED))
  80 +               return;
  81 +
  82         qdio_perf_stat_inc(&perf_stats.pci_int);
  83
  84         for_each_input_queue(irq_ptr, q, i)
  85 @@ -1072,11 +1080,11 @@ static void qdio_shutdown_queues(struct
  86         int i;
  87
  88         for_each_input_queue(irq_ptr, q, i)
  89 -               tasklet_disable(&q->tasklet);
  90 +               tasklet_kill(&q->tasklet);
  91
  92         for_each_output_queue(irq_ptr, q, i) {
  93 -               tasklet_disable(&q->tasklet);
  94                 del_timer(&q->u.out.timer);
  95 +               tasklet_kill(&q->tasklet);
  96         }
  97  }
  98
  99 @@ -1107,6 +1115,12 @@ int qdio_shutdown(struct ccw_device *cde
 100                 return 0;
 101         }
 102
 103 +       /*
 104 +        * Indicate that the device is going down. Scheduling the queue
 105 +        * tasklets is forbidden from here on.
 106 +        */
 107 +       qdio_set_state(irq_ptr, QDIO_IRQ_STATE_STOPPED);
 108 +
 109         tiqdio_remove_input_queues(irq_ptr);
 110         qdio_shutdown_queues(cdev);
 111         qdio_shutdown_debug_entries(irq_ptr, cdev);
 112 @@ -1526,7 +1540,6 @@ static int handle_outbound(struct qdio_q
 113                 qdio_perf_stat_inc(&perf_stats.fast_requeue);
 114         }
 115  out:
 116 -       /* Fixme: could wait forever if called from process context */
 117         tasklet_schedule(&q->tasklet);
 118         return rc;
 119  }
 120 Index: linux-sles11/drivers/s390/cio/qdio_thinint.c
 121 ===================================================================
 122 --- linux-sles11.orig/drivers/s390/cio/qdio_thinint.c
 123 +++ linux-sles11/drivers/s390/cio/qdio_thinint.c
 124 @@ -101,7 +101,6 @@ void tiqdio_add_input_queues(struct qdio
 125                 list_add_rcu(&q->entry, &tiq_list);
 126         mutex_unlock(&tiq_list_lock);
 127         xchg(irq_ptr->dsci, 1);
 128 -       tasklet_schedule(&tiqdio_tasklet);
 129  }
 130
 131  /*
 132 @@ -159,7 +158,6 @@ static void __tiqdio_inbound_processing(
 133          */
 134         qdio_check_outbound_after_thinint(q);
 135
 136 -again:
 137         if (!qdio_inbound_q_moved(q))
 138                 return;
 139
 140 @@ -167,7 +165,8 @@ again:
 141
 142         if (!tiqdio_inbound_q_done(q)) {
 143                 qdio_perf_stat_inc(&perf_stats.thinint_inbound_loop);
 144 -               goto again;
 145 +               if (likely(q->irq_ptr->state != QDIO_IRQ_STATE_STOPPED))
 146 +                       tasklet_schedule(&q->tasklet);
 147         }
 148
 149         qdio_stop_polling(q);
 150 @@ -177,7 +176,8 @@ again:
 151          */
 152         if (!tiqdio_inbound_q_done(q)) {
 153                 qdio_perf_stat_inc(&perf_stats.thinint_inbound_loop2);
 154 -               goto again;
 155 +               if (likely(q->irq_ptr->state != QDIO_IRQ_STATE_STOPPED))
 156 +                       tasklet_schedule(&q->tasklet);
 157         }
 158  }
 159