135 lines
3.4 KiB
C
135 lines
3.4 KiB
C
/*********************************************************************
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*
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* sir_dongle.c: manager for serial dongle protocol drivers
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*
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* Copyright (c) 2002 Martin Diehl
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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********************************************************************/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/kmod.h>
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#include <linux/mutex.h>
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#include <net/irda/irda.h>
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#include "sir-dev.h"
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/**************************************************************************
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*
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* dongle registration and attachment
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*
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*/
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static LIST_HEAD(dongle_list); /* list of registered dongle drivers */
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static DEFINE_MUTEX(dongle_list_lock); /* protects the list */
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int irda_register_dongle(struct dongle_driver *new)
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{
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struct list_head *entry;
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struct dongle_driver *drv;
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IRDA_DEBUG(0, "%s : registering dongle \"%s\" (%d).\n",
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__func__, new->driver_name, new->type);
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mutex_lock(&dongle_list_lock);
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list_for_each(entry, &dongle_list) {
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drv = list_entry(entry, struct dongle_driver, dongle_list);
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if (new->type == drv->type) {
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mutex_unlock(&dongle_list_lock);
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return -EEXIST;
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}
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}
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list_add(&new->dongle_list, &dongle_list);
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mutex_unlock(&dongle_list_lock);
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return 0;
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}
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EXPORT_SYMBOL(irda_register_dongle);
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int irda_unregister_dongle(struct dongle_driver *drv)
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{
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mutex_lock(&dongle_list_lock);
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list_del(&drv->dongle_list);
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mutex_unlock(&dongle_list_lock);
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return 0;
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}
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EXPORT_SYMBOL(irda_unregister_dongle);
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int sirdev_get_dongle(struct sir_dev *dev, IRDA_DONGLE type)
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{
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struct list_head *entry;
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const struct dongle_driver *drv = NULL;
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int err = -EINVAL;
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request_module("irda-dongle-%d", type);
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if (dev->dongle_drv != NULL)
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return -EBUSY;
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/* serialize access to the list of registered dongles */
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mutex_lock(&dongle_list_lock);
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list_for_each(entry, &dongle_list) {
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drv = list_entry(entry, struct dongle_driver, dongle_list);
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if (drv->type == type)
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break;
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else
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drv = NULL;
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}
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if (!drv) {
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err = -ENODEV;
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goto out_unlock; /* no such dongle */
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}
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/* handling of SMP races with dongle module removal - three cases:
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* 1) dongle driver was already unregistered - then we haven't found the
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* requested dongle above and are already out here
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* 2) the module is already marked deleted but the driver is still
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* registered - then the try_module_get() below will fail
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* 3) the try_module_get() below succeeds before the module is marked
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* deleted - then sys_delete_module() fails and prevents the removal
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* because the module is in use.
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*/
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if (!try_module_get(drv->owner)) {
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err = -ESTALE;
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goto out_unlock; /* rmmod already pending */
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}
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dev->dongle_drv = drv;
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if (!drv->open || (err=drv->open(dev))!=0)
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goto out_reject; /* failed to open driver */
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mutex_unlock(&dongle_list_lock);
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return 0;
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out_reject:
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dev->dongle_drv = NULL;
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module_put(drv->owner);
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out_unlock:
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mutex_unlock(&dongle_list_lock);
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return err;
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}
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int sirdev_put_dongle(struct sir_dev *dev)
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{
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const struct dongle_driver *drv = dev->dongle_drv;
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if (drv) {
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if (drv->close)
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drv->close(dev); /* close this dongle instance */
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dev->dongle_drv = NULL; /* unlink the dongle driver */
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module_put(drv->owner);/* decrement driver's module refcount */
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}
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return 0;
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}
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