--- /dev/null
+/*
+ * SCSI device handler infrastruture.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright IBM Corporation, 2007
+ * Authors:
+ * Chandra Seetharaman <sekharan@us.ibm.com>
+ * Mike Anderson <andmike@linux.vnet.ibm.com>
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <scsi/scsi_dh.h>
+#include "../scsi_priv.h"
+
+static DEFINE_SPINLOCK(list_lock);
+static LIST_HEAD(scsi_dh_list);
+
+static struct scsi_device_handler *get_device_handler(const char *name)
+{
+ struct scsi_device_handler *tmp, *found = NULL;
+
+ spin_lock(&list_lock);
+ list_for_each_entry(tmp, &scsi_dh_list, list) {
+ if (!strncmp(tmp->name, name, strlen(tmp->name))) {
+ found = tmp;
+ break;
+ }
+ }
+ spin_unlock(&list_lock);
+ return found;
+}
+
+/*
+ * device_handler_match_function - Match a device handler to a device
+ * @sdev - SCSI device to be tested
+ *
+ * Tests @sdev against the match function of all registered device_handler.
+ * Returns the found device handler or NULL if not found.
+ */
+static struct scsi_device_handler *
+device_handler_match_function(struct scsi_device *sdev)
+{
+ struct scsi_device_handler *tmp_dh, *found_dh = NULL;
+
+ spin_lock(&list_lock);
+ list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
+ if (tmp_dh->match && tmp_dh->match(sdev)) {
+ found_dh = tmp_dh;
+ break;
+ }
+ }
+ spin_unlock(&list_lock);
+ return found_dh;
+}
+
+/*
+ * device_handler_match - Attach a device handler to a device
+ * @scsi_dh - The device handler to match against or NULL
+ * @sdev - SCSI device to be tested against @scsi_dh
+ *
+ * Tests @sdev against the device handler @scsi_dh or against
+ * all registered device_handler if @scsi_dh == NULL.
+ * Returns the found device handler or NULL if not found.
+ */
+static struct scsi_device_handler *
+device_handler_match(struct scsi_device_handler *scsi_dh,
+ struct scsi_device *sdev)
+{
+ struct scsi_device_handler *found_dh;
+
+ found_dh = device_handler_match_function(sdev);
+
+ if (scsi_dh && found_dh != scsi_dh)
+ found_dh = NULL;
+
+ return found_dh;
+}
+
+/*
+ * scsi_dh_handler_attach - Attach a device handler to a device
+ * @sdev - SCSI device the device handler should attach to
+ * @scsi_dh - The device handler to attach
+ */
+static int scsi_dh_handler_attach(struct scsi_device *sdev,
+ struct scsi_device_handler *scsi_dh)
+{
+ struct scsi_dh_data *d;
+
+ if (sdev->scsi_dh_data) {
+ if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
+ return -EBUSY;
+
+ kref_get(&sdev->scsi_dh_data->kref);
+ return 0;
+ }
+
+ if (!try_module_get(scsi_dh->module))
+ return -EINVAL;
+
+ d = scsi_dh->attach(sdev);
+ if (IS_ERR(d)) {
+ sdev_printk(KERN_ERR, sdev, "%s: Attach failed (%ld)\n",
+ scsi_dh->name, PTR_ERR(d));
+ module_put(scsi_dh->module);
+ return PTR_ERR(d);
+ }
+
+ d->scsi_dh = scsi_dh;
+ kref_init(&d->kref);
+ d->sdev = sdev;
+
+ spin_lock_irq(sdev->request_queue->queue_lock);
+ sdev->scsi_dh_data = d;
+ spin_unlock_irq(sdev->request_queue->queue_lock);
+ return 0;
+}
+
+static void __detach_handler (struct kref *kref)
+{
+ struct scsi_dh_data *scsi_dh_data =
+ container_of(kref, struct scsi_dh_data, kref);
+ struct scsi_device_handler *scsi_dh = scsi_dh_data->scsi_dh;
+ struct scsi_device *sdev = scsi_dh_data->sdev;
+
+ scsi_dh->detach(sdev);
+
+ spin_lock_irq(sdev->request_queue->queue_lock);
+ sdev->scsi_dh_data = NULL;
+ spin_unlock_irq(sdev->request_queue->queue_lock);
+
+ sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", scsi_dh->name);
+ module_put(scsi_dh->module);
+}
+
+/*
+ * scsi_dh_handler_detach - Detach a device handler from a device
+ * @sdev - SCSI device the device handler should be detached from
+ * @scsi_dh - Device handler to be detached
+ *
+ * Detach from a device handler. If a device handler is specified,
+ * only detach if the currently attached handler matches @scsi_dh.
+ */
+static void scsi_dh_handler_detach(struct scsi_device *sdev,
+ struct scsi_device_handler *scsi_dh)
+{
+ if (!sdev->scsi_dh_data)
+ return;
+
+ if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
+ return;
+
+ if (!scsi_dh)
+ scsi_dh = sdev->scsi_dh_data->scsi_dh;
+
+ if (scsi_dh)
+ kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
+}
+
+/*
+ * Functions for sysfs attribute 'dh_state'
+ */
+static ssize_t
+store_dh_state(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct scsi_device *sdev = to_scsi_device(dev);
+ struct scsi_device_handler *scsi_dh;
+ int err = -EINVAL;
+
+ if (sdev->sdev_state == SDEV_CANCEL ||
+ sdev->sdev_state == SDEV_DEL)
+ return -ENODEV;
+
+ if (!sdev->scsi_dh_data) {
+ /*
+ * Attach to a device handler
+ */
+ if (!(scsi_dh = get_device_handler(buf)))
+ return err;
+ err = scsi_dh_handler_attach(sdev, scsi_dh);
+ } else {
+ scsi_dh = sdev->scsi_dh_data->scsi_dh;
+ if (!strncmp(buf, "detach", 6)) {
+ /*
+ * Detach from a device handler
+ */
+ scsi_dh_handler_detach(sdev, scsi_dh);
+ err = 0;
+ } else if (!strncmp(buf, "activate", 8)) {
+ /*
+ * Activate a device handler
+ */
+ if (scsi_dh->activate)
+ err = scsi_dh->activate(sdev, NULL, NULL);
+ else
+ err = 0;
+ }
+ }
+
+ return err<0?err:count;
+}
+
+static ssize_t
+show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct scsi_device *sdev = to_scsi_device(dev);
+
+ if (!sdev->scsi_dh_data)
+ return snprintf(buf, 20, "detached\n");
+
+ return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
+}
+
+static struct device_attribute scsi_dh_state_attr =
+ __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
+ store_dh_state);
+
+/*
+ * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
+ */
+static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
+{
+ struct scsi_device *sdev;
+ int err;
+
+ if (!scsi_is_sdev_device(dev))
+ return 0;
+
+ sdev = to_scsi_device(dev);
+
+ err = device_create_file(&sdev->sdev_gendev,
+ &scsi_dh_state_attr);
+
+ return 0;
+}
+
+/*
+ * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
+ */
+static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
+{
+ struct scsi_device *sdev;
+
+ if (!scsi_is_sdev_device(dev))
+ return 0;
+
+ sdev = to_scsi_device(dev);
+
+ device_remove_file(&sdev->sdev_gendev,
+ &scsi_dh_state_attr);
+
+ return 0;
+}
+
+/*
+ * scsi_dh_notifier - notifier chain callback
+ */
+static int scsi_dh_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct device *dev = data;
+ struct scsi_device *sdev;
+ int err = 0;
+ struct scsi_device_handler *devinfo = NULL;
+
+ if (!scsi_is_sdev_device(dev))
+ return 0;
+
+ sdev = to_scsi_device(dev);
+
+ if (action == BUS_NOTIFY_ADD_DEVICE) {
+ err = device_create_file(dev, &scsi_dh_state_attr);
+ /* don't care about err */
+ devinfo = device_handler_match(NULL, sdev);
+ if (devinfo)
+ err = scsi_dh_handler_attach(sdev, devinfo);
+ } else if (action == BUS_NOTIFY_DEL_DEVICE) {
+ device_remove_file(dev, &scsi_dh_state_attr);
+ scsi_dh_handler_detach(sdev, NULL);
+ }
+ return err;
+}
+
+/*
+ * scsi_dh_notifier_add - Callback for scsi_register_device_handler
+ */
+static int scsi_dh_notifier_add(struct device *dev, void *data)
+{
+ struct scsi_device_handler *scsi_dh = data;
+ struct scsi_device *sdev;
+
+ if (!scsi_is_sdev_device(dev))
+ return 0;
+
+ if (!get_device(dev))
+ return 0;
+
+ sdev = to_scsi_device(dev);
+
+ if (device_handler_match(scsi_dh, sdev))
+ scsi_dh_handler_attach(sdev, scsi_dh);
+
+ put_device(dev);
+
+ return 0;
+}
+
+/*
+ * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
+ */
+static int scsi_dh_notifier_remove(struct device *dev, void *data)
+{
+ struct scsi_device_handler *scsi_dh = data;
+ struct scsi_device *sdev;
+
+ if (!scsi_is_sdev_device(dev))
+ return 0;
+
+ if (!get_device(dev))
+ return 0;
+
+ sdev = to_scsi_device(dev);
+
+ scsi_dh_handler_detach(sdev, scsi_dh);
+
+ put_device(dev);
+
+ return 0;
+}
+
+/*
+ * scsi_register_device_handler - register a device handler personality
+ * module.
+ * @scsi_dh - device handler to be registered.
+ *
+ * Returns 0 on success, -EBUSY if handler already registered.
+ */
+int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
+{
+
+ if (get_device_handler(scsi_dh->name))
+ return -EBUSY;
+
+ if (!scsi_dh->attach || !scsi_dh->detach)
+ return -EINVAL;
+
+ spin_lock(&list_lock);
+ list_add(&scsi_dh->list, &scsi_dh_list);
+ spin_unlock(&list_lock);
+
+ bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
+ printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
+
+ return SCSI_DH_OK;
+}
+EXPORT_SYMBOL_GPL(scsi_register_device_handler);
+
+/*
+ * scsi_unregister_device_handler - register a device handler personality
+ * module.
+ * @scsi_dh - device handler to be unregistered.
+ *
+ * Returns 0 on success, -ENODEV if handler not registered.
+ */
+int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
+{
+
+ if (!get_device_handler(scsi_dh->name))
+ return -ENODEV;
+
+ bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
+ scsi_dh_notifier_remove);
+
+ spin_lock(&list_lock);
+ list_del(&scsi_dh->list);
+ spin_unlock(&list_lock);
+ printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
+
+ return SCSI_DH_OK;
+}
+EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
+
+/*
+ * scsi_dh_activate - activate the path associated with the scsi_device
+ * corresponding to the given request queue.
+ * Returns immediately without waiting for activation to be completed.
+ * @q - Request queue that is associated with the scsi_device to be
+ * activated.
+ * @fn - Function to be called upon completion of the activation.
+ * Function fn is called with data (below) and the error code.
+ * Function fn may be called from the same calling context. So,
+ * do not hold the lock in the caller which may be needed in fn.
+ * @data - data passed to the function fn upon completion.
+ *
+ */
+int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
+{
+ int err = 0;
+ unsigned long flags;
+ struct scsi_device *sdev;
+ struct scsi_device_handler *scsi_dh = NULL;
+ struct device *dev = NULL;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ sdev = q->queuedata;
+ if (!sdev) {
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ err = SCSI_DH_NOSYS;
+ if (fn)
+ fn(data, err);
+ return err;
+ }
+
+ if (sdev->scsi_dh_data)
+ scsi_dh = sdev->scsi_dh_data->scsi_dh;
+ dev = get_device(&sdev->sdev_gendev);
+ if (!scsi_dh || !dev ||
+ sdev->sdev_state == SDEV_CANCEL ||
+ sdev->sdev_state == SDEV_DEL)
+ err = SCSI_DH_NOSYS;
+ if (sdev->sdev_state == SDEV_OFFLINE)
+ err = SCSI_DH_DEV_OFFLINED;
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (err) {
+ if (fn)
+ fn(data, err);
+ goto out;
+ }
+
+ if (scsi_dh->activate)
+ err = scsi_dh->activate(sdev, fn, data);
+out:
+ put_device(dev);
+ return err;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_activate);
+
+/*
+ * scsi_dh_set_params - set the parameters for the device as per the
+ * string specified in params.
+ * @q - Request queue that is associated with the scsi_device for
+ * which the parameters to be set.
+ * @params - parameters in the following format
+ * "no_of_params\0param1\0param2\0param3\0...\0"
+ * for example, string for 2 parameters with value 10 and 21
+ * is specified as "2\010\021\0".
+ */
+int scsi_dh_set_params(struct request_queue *q, const char *params)
+{
+ int err = -SCSI_DH_NOSYS;
+ unsigned long flags;
+ struct scsi_device *sdev;
+ struct scsi_device_handler *scsi_dh = NULL;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ sdev = q->queuedata;
+ if (sdev && sdev->scsi_dh_data)
+ scsi_dh = sdev->scsi_dh_data->scsi_dh;
+ if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
+ err = 0;
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (err)
+ return err;
+ err = scsi_dh->set_params(sdev, params);
+ put_device(&sdev->sdev_gendev);
+ return err;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_set_params);
+
+/*
+ * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
+ * the given name. FALSE(0) otherwise.
+ * @name - name of the device handler.
+ */
+int scsi_dh_handler_exist(const char *name)
+{
+ return (get_device_handler(name) != NULL);
+}
+EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
+
+/*
+ * scsi_dh_attach - Attach device handler
+ * @q - Request queue that is associated with the scsi_device
+ * the handler should be attached to
+ * @name - name of the handler to attach
+ */
+int scsi_dh_attach(struct request_queue *q, const char *name)
+{
+ unsigned long flags;
+ struct scsi_device *sdev;
+ struct scsi_device_handler *scsi_dh;
+ int err = 0;
+
+ scsi_dh = get_device_handler(name);
+ if (!scsi_dh)
+ return -EINVAL;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ sdev = q->queuedata;
+ if (!sdev || !get_device(&sdev->sdev_gendev))
+ err = -ENODEV;
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (!err) {
+ err = scsi_dh_handler_attach(sdev, scsi_dh);
+ put_device(&sdev->sdev_gendev);
+ }
+ return err;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_attach);
+
+/*
+ * scsi_dh_detach - Detach device handler
+ * @q - Request queue that is associated with the scsi_device
+ * the handler should be detached from
+ *
+ * This function will detach the device handler only
+ * if the sdev is not part of the internal list, ie
+ * if it has been attached manually.
+ */
+void scsi_dh_detach(struct request_queue *q)
+{
+ unsigned long flags;
+ struct scsi_device *sdev;
+ struct scsi_device_handler *scsi_dh = NULL;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ sdev = q->queuedata;
+ if (!sdev || !get_device(&sdev->sdev_gendev))
+ sdev = NULL;
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (!sdev)
+ return;
+
+ if (sdev->scsi_dh_data) {
+ scsi_dh = sdev->scsi_dh_data->scsi_dh;
+ scsi_dh_handler_detach(sdev, scsi_dh);
+ }
+ put_device(&sdev->sdev_gendev);
+}
+EXPORT_SYMBOL_GPL(scsi_dh_detach);
+
+/*
+ * scsi_dh_attached_handler_name - Get attached device handler's name
+ * @q - Request queue that is associated with the scsi_device
+ * that may have a device handler attached
+ * @gfp - the GFP mask used in the kmalloc() call when allocating memory
+ *
+ * Returns name of attached handler, NULL if no handler is attached.
+ * Caller must take care to free the returned string.
+ */
+const char *scsi_dh_attached_handler_name(struct request_queue *q, gfp_t gfp)
+{
+ unsigned long flags;
+ struct scsi_device *sdev;
+ const char *handler_name = NULL;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ sdev = q->queuedata;
+ if (!sdev || !get_device(&sdev->sdev_gendev))
+ sdev = NULL;
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (!sdev)
+ return NULL;
+
+ if (sdev->scsi_dh_data)
+ handler_name = kstrdup(sdev->scsi_dh_data->scsi_dh->name, gfp);
+
+ put_device(&sdev->sdev_gendev);
+ return handler_name;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);
+
+static struct notifier_block scsi_dh_nb = {
+ .notifier_call = scsi_dh_notifier
+};
+
+static int __init scsi_dh_init(void)
+{
+ int r;
+
+ r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
+
+ if (!r)
+ bus_for_each_dev(&scsi_bus_type, NULL, NULL,
+ scsi_dh_sysfs_attr_add);
+
+ return r;
+}
+
+static void __exit scsi_dh_exit(void)
+{
+ bus_for_each_dev(&scsi_bus_type, NULL, NULL,
+ scsi_dh_sysfs_attr_remove);
+ bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
+}
+
+module_init(scsi_dh_init);
+module_exit(scsi_dh_exit);
+
+MODULE_DESCRIPTION("SCSI device handler");
+MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff