releases/3.6.2/scsi-zfcp-restore-refcount-check-on-port_remove.patch

   1 From d99b601b63386f3395dc26a699ae703a273d9982 Mon Sep 17 00:00:00 2001
   2 From: Steffen Maier <maier@linux.vnet.ibm.com>
   3 Date: Tue, 4 Sep 2012 15:23:34 +0200
   4 Subject: SCSI: zfcp: restore refcount check on port_remove
   5
   6 From: Steffen Maier <maier@linux.vnet.ibm.com>
   7
   8 commit d99b601b63386f3395dc26a699ae703a273d9982 upstream.
   9
  10 Upstream commit f3450c7b917201bb49d67032e9f60d5125675d6a
  11 "[SCSI] zfcp: Replace local reference counting with common kref"
  12 accidentally dropped a reference count check before tearing down
  13 zfcp_ports that are potentially in use by zfcp_units.
  14 Even remote ports in use can be removed causing
  15 unreachable garbage objects zfcp_ports with zfcp_units.
  16 Thus units won't come back even after a manual port_rescan.
  17 The kref of zfcp_port->dev.kobj is already used by the driver core.
  18 We cannot re-use it to track the number of zfcp_units.
  19 Re-introduce our own counter for units per port
  20 and check on port_remove.
  21
  22 Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
  23 Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
  24 Signed-off-by: James Bottomley <JBottomley@Parallels.com>
  25 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  26
  27 ---
  28  drivers/s390/scsi/zfcp_aux.c   |    1 +
  29  drivers/s390/scsi/zfcp_def.h   |    1 +
  30  drivers/s390/scsi/zfcp_ext.h   |    1 +
  31  drivers/s390/scsi/zfcp_sysfs.c |   18 ++++++++++++++++--
  32  drivers/s390/scsi/zfcp_unit.c  |   36 ++++++++++++++++++++++++++----------
  33  5 files changed, 45 insertions(+), 12 deletions(-)
  34
  35 --- a/drivers/s390/scsi/zfcp_aux.c
  36 +++ b/drivers/s390/scsi/zfcp_aux.c
  37 @@ -519,6 +519,7 @@ struct zfcp_port *zfcp_port_enqueue(stru
  38
  39         rwlock_init(&port->unit_list_lock);
  40         INIT_LIST_HEAD(&port->unit_list);
  41 +       atomic_set(&port->units, 0);
  42
  43         INIT_WORK(&port->gid_pn_work, zfcp_fc_port_did_lookup);
  44         INIT_WORK(&port->test_link_work, zfcp_fc_link_test_work);
  45 --- a/drivers/s390/scsi/zfcp_def.h
  46 +++ b/drivers/s390/scsi/zfcp_def.h
  47 @@ -205,6 +205,7 @@ struct zfcp_port {
  48         struct zfcp_adapter    *adapter;       /* adapter used to access port */
  49         struct list_head        unit_list;      /* head of logical unit list */
  50         rwlock_t                unit_list_lock; /* unit list lock */
  51 +       atomic_t                units;         /* zfcp_unit count */
  52         atomic_t               status;         /* status of this remote port */
  53         u64                    wwnn;           /* WWNN if known */
  54         u64                    wwpn;           /* WWPN */
  55 --- a/drivers/s390/scsi/zfcp_ext.h
  56 +++ b/drivers/s390/scsi/zfcp_ext.h
  57 @@ -159,6 +159,7 @@ extern void zfcp_scsi_dif_sense_error(st
  58  extern struct attribute_group zfcp_sysfs_unit_attrs;
  59  extern struct attribute_group zfcp_sysfs_adapter_attrs;
  60  extern struct attribute_group zfcp_sysfs_port_attrs;
  61 +extern struct mutex zfcp_sysfs_port_units_mutex;
  62  extern struct device_attribute *zfcp_sysfs_sdev_attrs[];
  63  extern struct device_attribute *zfcp_sysfs_shost_attrs[];
  64
  65 --- a/drivers/s390/scsi/zfcp_sysfs.c
  66 +++ b/drivers/s390/scsi/zfcp_sysfs.c
  67 @@ -227,6 +227,8 @@ static ssize_t zfcp_sysfs_port_rescan_st
  68  static ZFCP_DEV_ATTR(adapter, port_rescan, S_IWUSR, NULL,
  69                      zfcp_sysfs_port_rescan_store);
  70
  71 +DEFINE_MUTEX(zfcp_sysfs_port_units_mutex);
  72 +
  73  static ssize_t zfcp_sysfs_port_remove_store(struct device *dev,
  74                                             struct device_attribute *attr,
  75                                             const char *buf, size_t count)
  76 @@ -249,6 +251,16 @@ static ssize_t zfcp_sysfs_port_remove_st
  77         else
  78                 retval = 0;
  79
  80 +       mutex_lock(&zfcp_sysfs_port_units_mutex);
  81 +       if (atomic_read(&port->units) > 0) {
  82 +               retval = -EBUSY;
  83 +               mutex_unlock(&zfcp_sysfs_port_units_mutex);
  84 +               goto out;
  85 +       }
  86 +       /* port is about to be removed, so no more unit_add */
  87 +       atomic_set(&port->units, -1);
  88 +       mutex_unlock(&zfcp_sysfs_port_units_mutex);
  89 +
  90         write_lock_irq(&adapter->port_list_lock);
  91         list_del(&port->list);
  92         write_unlock_irq(&adapter->port_list_lock);
  93 @@ -289,12 +301,14 @@ static ssize_t zfcp_sysfs_unit_add_store
  94  {
  95         struct zfcp_port *port = container_of(dev, struct zfcp_port, dev);
  96         u64 fcp_lun;
  97 +       int retval;
  98
  99         if (strict_strtoull(buf, 0, (unsigned long long *) &fcp_lun))
 100                 return -EINVAL;
 101
 102 -       if (zfcp_unit_add(port, fcp_lun))
 103 -               return -EINVAL;
 104 +       retval = zfcp_unit_add(port, fcp_lun);
 105 +       if (retval)
 106 +               return retval;
 107
 108         return count;
 109  }
 110 --- a/drivers/s390/scsi/zfcp_unit.c
 111 +++ b/drivers/s390/scsi/zfcp_unit.c
 112 @@ -104,7 +104,7 @@ static void zfcp_unit_release(struct dev
 113  {
 114         struct zfcp_unit *unit = container_of(dev, struct zfcp_unit, dev);
 115
 116 -       put_device(&unit->port->dev);
 117 +       atomic_dec(&unit->port->units);
 118         kfree(unit);
 119  }
 120
 121 @@ -119,16 +119,27 @@ static void zfcp_unit_release(struct dev
 122  int zfcp_unit_add(struct zfcp_port *port, u64 fcp_lun)
 123  {
 124         struct zfcp_unit *unit;
 125 +       int retval = 0;
 126 +
 127 +       mutex_lock(&zfcp_sysfs_port_units_mutex);
 128 +       if (atomic_read(&port->units) == -1) {
 129 +               /* port is already gone */
 130 +               retval = -ENODEV;
 131 +               goto out;
 132 +       }
 133
 134         unit = zfcp_unit_find(port, fcp_lun);
 135         if (unit) {
 136                 put_device(&unit->dev);
 137 -               return -EEXIST;
 138 +               retval = -EEXIST;
 139 +               goto out;
 140         }
 141
 142         unit = kzalloc(sizeof(struct zfcp_unit), GFP_KERNEL);
 143 -       if (!unit)
 144 -               return -ENOMEM;
 145 +       if (!unit) {
 146 +               retval = -ENOMEM;
 147 +               goto out;
 148 +       }
 149
 150         unit->port = port;
 151         unit->fcp_lun = fcp_lun;
 152 @@ -139,28 +150,33 @@ int zfcp_unit_add(struct zfcp_port *port
 153         if (dev_set_name(&unit->dev, "0x%016llx",
 154                          (unsigned long long) fcp_lun)) {
 155                 kfree(unit);
 156 -               return -ENOMEM;
 157 +               retval = -ENOMEM;
 158 +               goto out;
 159         }
 160
 161 -       get_device(&port->dev);
 162 -
 163         if (device_register(&unit->dev)) {
 164                 put_device(&unit->dev);
 165 -               return -ENOMEM;
 166 +               retval = -ENOMEM;
 167 +               goto out;
 168         }
 169
 170         if (sysfs_create_group(&unit->dev.kobj, &zfcp_sysfs_unit_attrs)) {
 171                 device_unregister(&unit->dev);
 172 -               return -EINVAL;
 173 +               retval = -EINVAL;
 174 +               goto out;
 175         }
 176
 177 +       atomic_inc(&port->units); /* under zfcp_sysfs_port_units_mutex ! */
 178 +
 179         write_lock_irq(&port->unit_list_lock);
 180         list_add_tail(&unit->list, &port->unit_list);
 181         write_unlock_irq(&port->unit_list_lock);
 182
 183         zfcp_unit_scsi_scan(unit);
 184
 185 -       return 0;
 186 +out:
 187 +       mutex_unlock(&zfcp_sysfs_port_units_mutex);
 188 +       return retval;
 189  }
 190
 191  /**