src/patches/suse-2.6.27.31/patches.arch/s390-11-06-qdio_tiq_list_lock.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: qdio: add missing tiq_list locking
   3 References: bnc#484767,LTC#52205
   4
   5 Symptom:     The system may hang if multiple qdio devices are added or
   6              removed in parallel.
   7 Problem:     Although reading the tiq_list is done using RCU adding and
   8              removing elements from the list must still happen locked since
   9              multiple qdio devices may change the list in parallel otherwise.
  10 Solution:    Add a mutex to protect the tiq_list.
  11
  12 Acked-by: John Jolly <jjolly@suse.de>
  13 ---
  14  drivers/s390/cio/qdio_main.c    |    1 +
  15  drivers/s390/cio/qdio_thinint.c |   10 +++++++---
  16  2 files changed, 8 insertions(+), 3 deletions(-)
  17
  18 Index: linux-sles11/drivers/s390/cio/qdio_main.c
  19 ===================================================================
  20 --- linux-sles11.orig/drivers/s390/cio/qdio_main.c
  21 +++ linux-sles11/drivers/s390/cio/qdio_main.c
  22 @@ -1094,6 +1094,7 @@ int qdio_shutdown(struct ccw_device *cde
  23         if (!irq_ptr)
  24                 return -ENODEV;
  25
  26 +       BUG_ON(irqs_disabled());
  27         DBF_EVENT("qshutdown:%4x", cdev->private->schid.sch_no);
  28
  29         mutex_lock(&irq_ptr->setup_mutex);
  30 Index: linux-sles11/drivers/s390/cio/qdio_thinint.c
  31 ===================================================================
  32 --- linux-sles11.orig/drivers/s390/cio/qdio_thinint.c
  33 +++ linux-sles11/drivers/s390/cio/qdio_thinint.c
  34 @@ -31,6 +31,7 @@
  35
  36  /* list of thin interrupt input queues */
  37  static LIST_HEAD(tiq_list);
  38 +DEFINE_MUTEX(tiq_list_lock);
  39
  40  /* adapter local summary indicator */
  41  static unsigned char *tiqdio_alsi;
  42 @@ -95,10 +96,10 @@ void tiqdio_add_input_queues(struct qdio
  43         if (!css_qdio_omit_svs && irq_ptr->siga_flag.sync)
  44                 css_qdio_omit_svs = 1;
  45
  46 -       for_each_input_queue(irq_ptr, q, i) {
  47 +       mutex_lock(&tiq_list_lock);
  48 +       for_each_input_queue(irq_ptr, q, i)
  49                 list_add_rcu(&q->entry, &tiq_list);
  50 -               synchronize_rcu();
  51 -       }
  52 +       mutex_unlock(&tiq_list_lock);
  53         xchg(irq_ptr->dsci, 1);
  54         tasklet_schedule(&tiqdio_tasklet);
  55  }
  56 @@ -118,7 +119,10 @@ void tiqdio_remove_input_queues(struct q
  57                 /* if establish triggered an error */
  58                 if (!q || !q->entry.prev || !q->entry.next)
  59                         continue;
  60 +
  61 +               mutex_lock(&tiq_list_lock);
  62                 list_del_rcu(&q->entry);
  63 +               mutex_unlock(&tiq_list_lock);
  64                 synchronize_rcu();
  65         }
  66  }