diff options
Diffstat (limited to 'kernel/drivers/scsi/device_handler/scsi_dh.c')
| -rw-r--r-- | kernel/drivers/scsi/device_handler/scsi_dh.c | 621 |
1 files changed, 621 insertions, 0 deletions
diff --git a/kernel/drivers/scsi/device_handler/scsi_dh.c b/kernel/drivers/scsi/device_handler/scsi_dh.c new file mode 100644 index 000000000..1efebc9ee --- /dev/null +++ b/kernel/drivers/scsi/device_handler/scsi_dh.c @@ -0,0 +1,621 @@ +/* + * 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"); |