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![Hannes Reinecke](/assets/img/avatar_default.png)
Create a cache of devices that are seen in a system. This will avoid the unnecessary traversal of the device list in the scsi_dh when there are multiple luns of a same type. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
546 lines
13 KiB
C
546 lines
13 KiB
C
/*
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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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#include <scsi/scsi_dh.h>
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#include "../scsi_priv.h"
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struct scsi_dh_devinfo_list {
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struct list_head node;
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char vendor[9];
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char model[17];
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struct scsi_device_handler *handler;
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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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static LIST_HEAD(scsi_dh_dev_list);
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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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spin_lock(&list_lock);
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list_for_each_entry(tmp, &scsi_dh_list, list) {
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if (!strncmp(tmp->name, name, strlen(tmp->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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static struct scsi_device_handler *
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scsi_dh_cache_lookup(struct scsi_device *sdev)
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{
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struct scsi_dh_devinfo_list *tmp;
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struct scsi_device_handler *found_dh = NULL;
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spin_lock(&list_lock);
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list_for_each_entry(tmp, &scsi_dh_dev_list, node) {
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if (!strncmp(sdev->vendor, tmp->vendor, strlen(tmp->vendor)) &&
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!strncmp(sdev->model, tmp->model, strlen(tmp->model))) {
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found_dh = tmp->handler;
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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_dh;
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}
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static int scsi_dh_handler_lookup(struct scsi_device_handler *scsi_dh,
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struct scsi_device *sdev)
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{
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int i, found = 0;
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for(i = 0; scsi_dh->devlist[i].vendor; i++) {
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if (!strncmp(sdev->vendor, scsi_dh->devlist[i].vendor,
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strlen(scsi_dh->devlist[i].vendor)) &&
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!strncmp(sdev->model, scsi_dh->devlist[i].model,
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strlen(scsi_dh->devlist[i].model))) {
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found = 1;
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break;
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}
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}
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return found;
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}
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/*
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* device_handler_match - Attach a device handler to a device
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* @scsi_dh - The device handler to match against or NULL
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* @sdev - SCSI device to be tested against @scsi_dh
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*
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* Tests @sdev against the device handler @scsi_dh or against
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* all registered device_handler if @scsi_dh == NULL.
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* Returns the found device handler or NULL if not found.
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*/
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static struct scsi_device_handler *
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device_handler_match(struct scsi_device_handler *scsi_dh,
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struct scsi_device *sdev)
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{
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struct scsi_device_handler *found_dh = NULL;
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struct scsi_dh_devinfo_list *tmp;
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found_dh = scsi_dh_cache_lookup(sdev);
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if (found_dh)
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return found_dh;
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if (scsi_dh) {
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if (scsi_dh_handler_lookup(scsi_dh, sdev))
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found_dh = scsi_dh;
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} else {
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struct scsi_device_handler *tmp_dh;
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spin_lock(&list_lock);
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list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
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if (scsi_dh_handler_lookup(tmp_dh, sdev))
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found_dh = tmp_dh;
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}
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spin_unlock(&list_lock);
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}
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if (found_dh) { /* If device is found, add it to the cache */
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tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
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if (tmp) {
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strncpy(tmp->vendor, sdev->vendor, 8);
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strncpy(tmp->model, sdev->model, 16);
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tmp->vendor[8] = '\0';
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tmp->model[16] = '\0';
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tmp->handler = found_dh;
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spin_lock(&list_lock);
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list_add(&tmp->node, &scsi_dh_dev_list);
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spin_unlock(&list_lock);
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} else {
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found_dh = NULL;
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}
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}
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return found_dh;
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}
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/*
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* scsi_dh_handler_attach - Attach a device handler to a device
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* @sdev - SCSI device the device handler should attach to
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* @scsi_dh - The device handler to attach
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*/
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static int scsi_dh_handler_attach(struct scsi_device *sdev,
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struct scsi_device_handler *scsi_dh)
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{
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int err = 0;
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if (sdev->scsi_dh_data) {
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if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
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err = -EBUSY;
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} else if (scsi_dh->attach)
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err = scsi_dh->attach(sdev);
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return err;
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}
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/*
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* scsi_dh_handler_detach - Detach a device handler from a device
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* @sdev - SCSI device the device handler should be detached from
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* @scsi_dh - Device handler to be detached
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*
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* Detach from a device handler. If a device handler is specified,
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* only detach if the currently attached handler matches @scsi_dh.
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*/
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static void scsi_dh_handler_detach(struct scsi_device *sdev,
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struct scsi_device_handler *scsi_dh)
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{
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if (!sdev->scsi_dh_data)
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return;
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if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
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return;
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if (!scsi_dh)
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scsi_dh = sdev->scsi_dh_data->scsi_dh;
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if (scsi_dh && scsi_dh->detach)
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scsi_dh->detach(sdev);
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}
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/*
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* Functions for sysfs attribute 'dh_state'
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*/
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static ssize_t
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store_dh_state(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct scsi_device *sdev = to_scsi_device(dev);
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struct scsi_device_handler *scsi_dh;
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int err = -EINVAL;
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if (!sdev->scsi_dh_data) {
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/*
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* Attach to a device handler
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*/
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if (!(scsi_dh = get_device_handler(buf)))
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return err;
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err = scsi_dh_handler_attach(sdev, scsi_dh);
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} else {
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scsi_dh = sdev->scsi_dh_data->scsi_dh;
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if (!strncmp(buf, "detach", 6)) {
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/*
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* Detach from a device handler
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*/
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scsi_dh_handler_detach(sdev, scsi_dh);
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err = 0;
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} else if (!strncmp(buf, "activate", 8)) {
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/*
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* Activate a device handler
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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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else
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err = 0;
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}
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}
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return err<0?err:count;
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}
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static ssize_t
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show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct scsi_device *sdev = to_scsi_device(dev);
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if (!sdev->scsi_dh_data)
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return snprintf(buf, 20, "detached\n");
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return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
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}
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static struct device_attribute scsi_dh_state_attr =
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__ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
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store_dh_state);
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/*
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* scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
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*/
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static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
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{
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struct scsi_device *sdev;
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int err;
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if (!scsi_is_sdev_device(dev))
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return 0;
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sdev = to_scsi_device(dev);
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err = device_create_file(&sdev->sdev_gendev,
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&scsi_dh_state_attr);
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return 0;
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}
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/*
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* scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
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*/
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static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
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{
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struct scsi_device *sdev;
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if (!scsi_is_sdev_device(dev))
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return 0;
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sdev = to_scsi_device(dev);
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device_remove_file(&sdev->sdev_gendev,
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&scsi_dh_state_attr);
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return 0;
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}
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/*
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* scsi_dh_notifier - notifier chain callback
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*/
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static int scsi_dh_notifier(struct notifier_block *nb,
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unsigned long action, void *data)
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{
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struct device *dev = data;
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struct scsi_device *sdev;
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int err = 0;
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struct scsi_device_handler *devinfo = NULL;
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if (!scsi_is_sdev_device(dev))
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return 0;
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sdev = to_scsi_device(dev);
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if (action == BUS_NOTIFY_ADD_DEVICE) {
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devinfo = device_handler_match(NULL, sdev);
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if (!devinfo)
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goto out;
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err = scsi_dh_handler_attach(sdev, devinfo);
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if (!err)
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err = device_create_file(dev, &scsi_dh_state_attr);
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} else if (action == BUS_NOTIFY_DEL_DEVICE) {
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device_remove_file(dev, &scsi_dh_state_attr);
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scsi_dh_handler_detach(sdev, NULL);
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}
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out:
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return err;
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}
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/*
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* scsi_dh_notifier_add - Callback for scsi_register_device_handler
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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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struct scsi_device *sdev;
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if (!scsi_is_sdev_device(dev))
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return 0;
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if (!get_device(dev))
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return 0;
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sdev = to_scsi_device(dev);
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if (device_handler_match(scsi_dh, sdev))
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scsi_dh_handler_attach(sdev, scsi_dh);
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put_device(dev);
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return 0;
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}
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/*
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* scsi_dh_notifier_remove - Callback for scsi_unregister_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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struct scsi_device *sdev;
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if (!scsi_is_sdev_device(dev))
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return 0;
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if (!get_device(dev))
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return 0;
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sdev = to_scsi_device(dev);
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scsi_dh_handler_detach(sdev, scsi_dh);
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put_device(dev);
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return 0;
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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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if (get_device_handler(scsi_dh->name))
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return -EBUSY;
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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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bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
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printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
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return SCSI_DH_OK;
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}
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EXPORT_SYMBOL_GPL(scsi_register_device_handler);
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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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struct scsi_dh_devinfo_list *tmp, *pos;
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if (!get_device_handler(scsi_dh->name))
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return -ENODEV;
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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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list_for_each_entry_safe(pos, tmp, &scsi_dh_dev_list, node) {
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if (pos->handler == scsi_dh) {
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list_del(&pos->node);
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kfree(pos);
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}
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}
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spin_unlock(&list_lock);
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printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
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return SCSI_DH_OK;
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}
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EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
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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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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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if (err)
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return err;
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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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* 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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* scsi_dh_handler_attach - Attach device handler
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* @sdev - sdev the handler should be attached to
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* @name - name of the handler to attach
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*/
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int scsi_dh_attach(struct request_queue *q, const char *name)
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{
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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;
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int err = 0;
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scsi_dh = get_device_handler(name);
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if (!scsi_dh)
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return -EINVAL;
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spin_lock_irqsave(q->queue_lock, flags);
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sdev = q->queuedata;
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if (!sdev || !get_device(&sdev->sdev_gendev))
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err = -ENODEV;
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spin_unlock_irqrestore(q->queue_lock, flags);
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if (!err) {
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err = scsi_dh_handler_attach(sdev, scsi_dh);
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put_device(&sdev->sdev_gendev);
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}
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return err;
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}
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EXPORT_SYMBOL_GPL(scsi_dh_attach);
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/*
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* scsi_dh_handler_detach - Detach device handler
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* @sdev - sdev the handler should be detached from
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*
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* This function will detach the device handler only
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* if the sdev is not part of the internal list, ie
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* if it has been attached manually.
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*/
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void scsi_dh_detach(struct request_queue *q)
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{
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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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spin_lock_irqsave(q->queue_lock, flags);
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sdev = q->queuedata;
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if (!sdev || !get_device(&sdev->sdev_gendev))
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sdev = NULL;
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spin_unlock_irqrestore(q->queue_lock, flags);
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if (!sdev)
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return;
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if (sdev->scsi_dh_data) {
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/* if sdev is not on internal list, detach */
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scsi_dh = sdev->scsi_dh_data->scsi_dh;
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if (!device_handler_match(scsi_dh, sdev))
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scsi_dh_handler_detach(sdev, scsi_dh);
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}
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put_device(&sdev->sdev_gendev);
|
|
}
|
|
EXPORT_SYMBOL_GPL(scsi_dh_detach);
|
|
|
|
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");
|