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   1 /*
   2  * SCSI device handler infrastruture.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the
   6  * Free Software Foundation; either version 2 of the License, or (at your
   7  * option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright IBM Corporation, 2007
  19  *      Authors:
  20  *               Chandra Seetharaman <sekharan@us.ibm.com>
  21  *               Mike Anderson <andmike@linux.vnet.ibm.com>
  22  */
  23
  24 #include <scsi/scsi_dh.h>
  25 #include "../scsi_priv.h"
  26
  27 static DEFINE_SPINLOCK(list_lock);
  28 static LIST_HEAD(scsi_dh_list);
  29
  30 static struct scsi_device_handler *get_device_handler(const char *name)
  31 {
  32         struct scsi_device_handler *tmp, *found = NULL;
  33
  34         spin_lock(&list_lock);
  35         list_for_each_entry(tmp, &scsi_dh_list, list) {
  36                 if (!strcmp(tmp->name, name)) {
  37                         found = tmp;
  38                         break;
  39                 }
  40         }
  41         spin_unlock(&list_lock);
  42         return found;
  43 }
  44
  45 static int scsi_dh_notifier_add(struct device *dev, void *data)
  46 {
  47         struct scsi_device_handler *scsi_dh = data;
  48
  49         scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_ADD_DEVICE, dev);
  50         return 0;
  51 }
  52
  53 /*
  54  * scsi_register_device_handler - register a device handler personality
  55  *      module.
  56  * @scsi_dh - device handler to be registered.
  57  *
  58  * Returns 0 on success, -EBUSY if handler already registered.
  59  */
  60 int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
  61 {
  62         int ret = -EBUSY;
  63         struct scsi_device_handler *tmp;
  64
  65         tmp = get_device_handler(scsi_dh->name);
  66         if (tmp)
  67                 goto done;
  68
  69         ret = bus_register_notifier(&scsi_bus_type, &scsi_dh->nb);
  70
  71         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
  72         spin_lock(&list_lock);
  73         list_add(&scsi_dh->list, &scsi_dh_list);
  74         spin_unlock(&list_lock);
  75
  76 done:
  77         return ret;
  78 }
  79 EXPORT_SYMBOL_GPL(scsi_register_device_handler);
  80
  81 static int scsi_dh_notifier_remove(struct device *dev, void *data)
  82 {
  83         struct scsi_device_handler *scsi_dh = data;
  84
  85         scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_DEL_DEVICE, dev);
  86         return 0;
  87 }
  88
  89 /*
  90  * scsi_unregister_device_handler - register a device handler personality
  91  *      module.
  92  * @scsi_dh - device handler to be unregistered.
  93  *
  94  * Returns 0 on success, -ENODEV if handler not registered.
  95  */
  96 int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
  97 {
  98         int ret = -ENODEV;
  99         struct scsi_device_handler *tmp;
 100
 101         tmp = get_device_handler(scsi_dh->name);
 102         if (!tmp)
 103                 goto done;
 104
 105         ret = bus_unregister_notifier(&scsi_bus_type, &scsi_dh->nb);
 106
 107         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
 108                                         scsi_dh_notifier_remove);
 109         spin_lock(&list_lock);
 110         list_del(&scsi_dh->list);
 111         spin_unlock(&list_lock);
 112
 113 done:
 114         return ret;
 115 }
 116 EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
 117
 118 /*
 119  * scsi_dh_activate - activate the path associated with the scsi_device
 120  *      corresponding to the given request queue.
 121  * @q - Request queue that is associated with the scsi_device to be
 122  *      activated.
 123  */
 124 int scsi_dh_activate(struct request_queue *q)
 125 {
 126         int err = 0;
 127         unsigned long flags;
 128         struct scsi_device *sdev;
 129         struct scsi_device_handler *scsi_dh = NULL;
 130
 131         spin_lock_irqsave(q->queue_lock, flags);
 132         sdev = q->queuedata;
 133         if (sdev && sdev->scsi_dh_data)
 134                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 135         if (!scsi_dh || !get_device(&sdev->sdev_gendev))
 136                 err = SCSI_DH_NOSYS;
 137         spin_unlock_irqrestore(q->queue_lock, flags);
 138
 139         if (err)
 140                 return err;
 141
 142         if (scsi_dh->activate)
 143                 err = scsi_dh->activate(sdev);
 144         put_device(&sdev->sdev_gendev);
 145         return err;
 146 }
 147 EXPORT_SYMBOL_GPL(scsi_dh_activate);
 148
 149 /*
 150  * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
 151  *      the given name. FALSE(0) otherwise.
 152  * @name - name of the device handler.
 153  */
 154 int scsi_dh_handler_exist(const char *name)
 155 {
 156         return (get_device_handler(name) != NULL);
 157 }
 158 EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
 159
 160 MODULE_DESCRIPTION("SCSI device handler");
 161 MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
 162 MODULE_LICENSE("GPL");