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@@ -0,0 +1,162 @@
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+/*
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+ * SCSI device handler infrastruture.
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+ *
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+ * This program is free software; you can redistribute it and/or modify it
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+ * under the terms of the GNU General Public License as published by the
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+ * Free Software Foundation; either version 2 of the License, or (at your
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+ * option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful, but
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+ * WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ * General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License along
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+ * with this program; if not, write to the Free Software Foundation, Inc.,
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+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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+ *
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+ * Copyright IBM Corporation, 2007
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+ * Authors:
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+ * Chandra Seetharaman <sekharan@us.ibm.com>
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+ * Mike Anderson <andmike@linux.vnet.ibm.com>
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+ */
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+
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+#include <scsi/scsi_dh.h>
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+#include "../scsi_priv.h"
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+
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+static DEFINE_SPINLOCK(list_lock);
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+static LIST_HEAD(scsi_dh_list);
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+
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+static struct scsi_device_handler *get_device_handler(const char *name)
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+{
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+ struct scsi_device_handler *tmp, *found = NULL;
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+
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+ spin_lock(&list_lock);
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+ list_for_each_entry(tmp, &scsi_dh_list, list) {
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+ if (!strcmp(tmp->name, name)) {
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+ found = tmp;
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+ break;
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+ }
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+ }
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+ spin_unlock(&list_lock);
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+ return found;
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+}
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+
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+static int scsi_dh_notifier_add(struct device *dev, void *data)
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+{
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+ struct scsi_device_handler *scsi_dh = data;
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+
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+ scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_ADD_DEVICE, dev);
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+ return 0;
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+}
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+
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+/*
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+ * scsi_register_device_handler - register a device handler personality
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+ * module.
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+ * @scsi_dh - device handler to be registered.
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+ *
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+ * Returns 0 on success, -EBUSY if handler already registered.
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+ */
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+int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
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+{
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+ int ret = -EBUSY;
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+ struct scsi_device_handler *tmp;
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+
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+ tmp = get_device_handler(scsi_dh->name);
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+ if (tmp)
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+ goto done;
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+
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+ ret = bus_register_notifier(&scsi_bus_type, &scsi_dh->nb);
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+
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+ bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
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+ spin_lock(&list_lock);
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+ list_add(&scsi_dh->list, &scsi_dh_list);
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+ spin_unlock(&list_lock);
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+
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+done:
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(scsi_register_device_handler);
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+
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+static int scsi_dh_notifier_remove(struct device *dev, void *data)
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+{
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+ struct scsi_device_handler *scsi_dh = data;
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+
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+ scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_DEL_DEVICE, dev);
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+ return 0;
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+}
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+
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+/*
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+ * scsi_unregister_device_handler - register a device handler personality
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+ * module.
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+ * @scsi_dh - device handler to be unregistered.
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+ *
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+ * Returns 0 on success, -ENODEV if handler not registered.
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+ */
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+int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
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+{
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+ int ret = -ENODEV;
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+ struct scsi_device_handler *tmp;
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+
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+ tmp = get_device_handler(scsi_dh->name);
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+ if (!tmp)
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+ goto done;
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+
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+ ret = bus_unregister_notifier(&scsi_bus_type, &scsi_dh->nb);
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+
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+ bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
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+ scsi_dh_notifier_remove);
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+ spin_lock(&list_lock);
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+ list_del(&scsi_dh->list);
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+ spin_unlock(&list_lock);
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+
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+done:
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
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+
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+/*
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+ * scsi_dh_activate - activate the path associated with the scsi_device
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+ * corresponding to the given request queue.
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+ * @q - Request queue that is associated with the scsi_device to be
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+ * activated.
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+ */
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+int scsi_dh_activate(struct request_queue *q)
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+{
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+ int err = 0;
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+ unsigned long flags;
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+ struct scsi_device *sdev;
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+ struct scsi_device_handler *scsi_dh = NULL;
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+
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+ spin_lock_irqsave(q->queue_lock, flags);
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+ sdev = q->queuedata;
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+ if (sdev && sdev->scsi_dh_data)
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+ scsi_dh = sdev->scsi_dh_data->scsi_dh;
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+ if (!scsi_dh || !get_device(&sdev->sdev_gendev))
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+ err = SCSI_DH_NOSYS;
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+ spin_unlock_irqrestore(q->queue_lock, flags);
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+
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+ if (err)
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+ return err;
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+
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+ if (scsi_dh->activate)
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+ err = scsi_dh->activate(sdev);
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+ put_device(&sdev->sdev_gendev);
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+ return err;
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+}
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+EXPORT_SYMBOL_GPL(scsi_dh_activate);
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+
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+/*
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+ * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
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+ * the given name. FALSE(0) otherwise.
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+ * @name - name of the device handler.
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+ */
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+int scsi_dh_handler_exist(const char *name)
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+{
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+ return (get_device_handler(name) != NULL);
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+}
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+EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
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+
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+MODULE_DESCRIPTION("SCSI device handler");
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+MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
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+MODULE_LICENSE("GPL");
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Chandra Seetharaman