src/patches/suse-2.6.27.25/patches.arch/s390-12-10-kernel_appldata_mutex.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: kernel: use mutex for appldata_ops instead of spin_lock.
   3 References: bnc#487755,LTC#52788
   4
   5 Symptom:     Possible deadlock when appldata_mem is active
   6 Problem:     The appldata_ops callbacks are called with a spin_lock held.
   7              But the appldata_mem callback then calls all_vm_events(), which
   8              calls get_online_cpus(), which might sleep.
   9 Solution:    Use a mutex instead of a spin_lock.
  10
  11 Acked-by: John Jolly <jjolly@suse.de>
  12 ---
  13  arch/s390/appldata/appldata_base.c |   32 ++++++++++++++++----------------
  14  arch/s390/appldata/appldata_mem.c  |    4 +---
  15  2 files changed, 17 insertions(+), 19 deletions(-)
  16
  17 Index: linux-sles11/arch/s390/appldata/appldata_base.c
  18 ===================================================================
  19 --- linux-sles11.orig/arch/s390/appldata/appldata_base.c
  20 +++ linux-sles11/arch/s390/appldata/appldata_base.c
  21 @@ -97,7 +97,7 @@ static DECLARE_WORK(appldata_work, appld
  22  /*
  23   * Ops list
  24   */
  25 -static DEFINE_SPINLOCK(appldata_ops_lock);
  26 +static DEFINE_MUTEX(appldata_ops_mutex);
  27  static LIST_HEAD(appldata_ops_list);
  28
  29
  30 @@ -128,14 +128,14 @@ static void appldata_work_fn(struct work
  31
  32         i = 0;
  33         get_online_cpus();
  34 -       spin_lock(&appldata_ops_lock);
  35 +       mutex_lock(&appldata_ops_mutex);
  36         list_for_each(lh, &appldata_ops_list) {
  37                 ops = list_entry(lh, struct appldata_ops, list);
  38                 if (ops->active == 1) {
  39                         ops->callback(ops->data);
  40                 }
  41         }
  42 -       spin_unlock(&appldata_ops_lock);
  43 +       mutex_unlock(&appldata_ops_mutex);
  44         put_online_cpus();
  45  }
  46
  47 @@ -337,7 +337,7 @@ appldata_generic_handler(ctl_table *ctl,
  48         struct list_head *lh;
  49
  50         found = 0;
  51 -       spin_lock(&appldata_ops_lock);
  52 +       mutex_lock(&appldata_ops_mutex);
  53         list_for_each(lh, &appldata_ops_list) {
  54                 tmp_ops = list_entry(lh, struct appldata_ops, list);
  55                 if (&tmp_ops->ctl_table[2] == ctl) {
  56 @@ -345,15 +345,15 @@ appldata_generic_handler(ctl_table *ctl,
  57                 }
  58         }
  59         if (!found) {
  60 -               spin_unlock(&appldata_ops_lock);
  61 +               mutex_unlock(&appldata_ops_mutex);
  62                 return -ENODEV;
  63         }
  64         ops = ctl->data;
  65         if (!try_module_get(ops->owner)) {      // protect this function
  66 -               spin_unlock(&appldata_ops_lock);
  67 +               mutex_unlock(&appldata_ops_mutex);
  68                 return -ENODEV;
  69         }
  70 -       spin_unlock(&appldata_ops_lock);
  71 +       mutex_unlock(&appldata_ops_mutex);
  72
  73         if (!*lenp || *ppos) {
  74                 *lenp = 0;
  75 @@ -377,11 +377,11 @@ appldata_generic_handler(ctl_table *ctl,
  76                 return -EFAULT;
  77         }
  78
  79 -       spin_lock(&appldata_ops_lock);
  80 +       mutex_lock(&appldata_ops_mutex);
  81         if ((buf[0] == '1') && (ops->active == 0)) {
  82                 // protect work queue callback
  83                 if (!try_module_get(ops->owner)) {
  84 -                       spin_unlock(&appldata_ops_lock);
  85 +                       mutex_unlock(&appldata_ops_mutex);
  86                         module_put(ops->owner);
  87                         return -ENODEV;
  88                 }
  89 @@ -406,7 +406,7 @@ appldata_generic_handler(ctl_table *ctl,
  90                                "failed with rc=%d\n", ops->name, rc);
  91                 module_put(ops->owner);
  92         }
  93 -       spin_unlock(&appldata_ops_lock);
  94 +       mutex_unlock(&appldata_ops_mutex);
  95  out:
  96         *lenp = len;
  97         *ppos += len;
  98 @@ -432,9 +432,9 @@ int appldata_register_ops(struct appldat
  99         if (!ops->ctl_table)
 100                 return -ENOMEM;
 101
 102 -       spin_lock(&appldata_ops_lock);
 103 +       mutex_lock(&appldata_ops_mutex);
 104         list_add(&ops->list, &appldata_ops_list);
 105 -       spin_unlock(&appldata_ops_lock);
 106 +       mutex_unlock(&appldata_ops_mutex);
 107
 108         ops->ctl_table[0].procname = appldata_proc_name;
 109         ops->ctl_table[0].maxlen   = 0;
 110 @@ -451,9 +451,9 @@ int appldata_register_ops(struct appldat
 111                 goto out;
 112         return 0;
 113  out:
 114 -       spin_lock(&appldata_ops_lock);
 115 +       mutex_lock(&appldata_ops_mutex);
 116         list_del(&ops->list);
 117 -       spin_unlock(&appldata_ops_lock);
 118 +       mutex_unlock(&appldata_ops_mutex);
 119         kfree(ops->ctl_table);
 120         return -ENOMEM;
 121  }
 122 @@ -465,9 +465,9 @@ out:
 123   */
 124  void appldata_unregister_ops(struct appldata_ops *ops)
 125  {
 126 -       spin_lock(&appldata_ops_lock);
 127 +       mutex_lock(&appldata_ops_mutex);
 128         list_del(&ops->list);
 129 -       spin_unlock(&appldata_ops_lock);
 130 +       mutex_unlock(&appldata_ops_mutex);
 131         unregister_sysctl_table(ops->sysctl_header);
 132         kfree(ops->ctl_table);
 133  }
 134 Index: linux-sles11/arch/s390/appldata/appldata_mem.c
 135 ===================================================================
 136 --- linux-sles11.orig/arch/s390/appldata/appldata_mem.c
 137 +++ linux-sles11/arch/s390/appldata/appldata_mem.c
 138 @@ -78,7 +78,7 @@ static void appldata_get_mem_data(void *
 139  {
 140         /*
 141          * don't put large structures on the stack, we are
 142 -        * serialized through the appldata_ops_lock and can use static
 143 +        * serialized through the appldata_ops_mutex and can use static
 144          */
 145         static struct sysinfo val;
 146         unsigned long ev[NR_VM_EVENT_ITEMS];