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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * Parallel-port resource manager code.
  *
  * Authors: David Campbell <campbell@tirian.che.curtin.edu.au>
  *          Tim Waugh <tim@cyberelk.demon.co.uk>
  *          Jose Renau <renau@acm.org>
  *          Philip Blundell <philb@gnu.org>
  *      Andrea Arcangeli
  *
  * based on work by Grant Guenther <grant@torque.net>
  *          and Philip Blundell
  *
  * Any part of this program may be used in documents licensed under
  * the GNU Free Documentation License, Version 1.1 or any later version
  * published by the Free Software Foundation.
  */
 
 #undef PARPORT_DEBUG_SHARING        /* undef for production */
 
 #include <linux/module.h>
 #include <linux/string.h>
 #include <linux/threads.h>
 #include <linux/parport.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/sched/signal.h>
 #include <linux/kmod.h>
 #include <linux/device.h>
 
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
 #include <asm/irq.h>
 
 #undef PARPORT_PARANOID
 
 #define PARPORT_DEFAULT_TIMESLICE   (HZ/5)
 
 unsigned long parport_default_timeslice = PARPORT_DEFAULT_TIMESLICE;
 int parport_default_spintime =  DEFAULT_SPIN_TIME;
 
 static LIST_HEAD(portlist);
 static DEFINE_SPINLOCK(parportlist_lock);
 
 /* list of all allocated ports, sorted by ->number */
 static LIST_HEAD(all_ports);
 static DEFINE_SPINLOCK(full_list_lock);
 
 static LIST_HEAD(drivers);
 
 static DEFINE_MUTEX(registration_lock);
 
 /* What you can do to a port that's gone away.. */
 static void dead_write_lines(struct parport *p, unsigned char b){}
 static unsigned char dead_read_lines(struct parport *p) { return 0; }
 static unsigned char dead_frob_lines(struct parport *p, unsigned char b,
                  unsigned char c) { return 0; }
 static void dead_onearg(struct parport *p){}
 static void dead_initstate(struct pardevice *d, struct parport_state *s) { }
 static void dead_state(struct parport *p, struct parport_state *s) { }
 static size_t dead_write(struct parport *p, const void *b, size_t l, int f)
 { return 0; }
 static size_t dead_read(struct parport *p, void *b, size_t l, int f)
 { return 0; }
 static struct parport_operations dead_ops = {
     .write_data = dead_write_lines, /* data */
     .read_data  = dead_read_lines,
 
     .write_control  = dead_write_lines, /* control */
     .read_control   = dead_read_lines,
     .frob_control   = dead_frob_lines,
 
     .read_status    = dead_read_lines,  /* status */
 
     .enable_irq = dead_onearg,      /* enable_irq */
     .disable_irq    = dead_onearg,      /* disable_irq */
 
     .data_forward   = dead_onearg,      /* data_forward */
     .data_reverse   = dead_onearg,      /* data_reverse */
 
     .init_state = dead_initstate,   /* init_state */
     .save_state = dead_state,
     .restore_state  = dead_state,
 
     .epp_write_data = dead_write,       /* epp */
     .epp_read_data  = dead_read,
     .epp_write_addr = dead_write,
     .epp_read_addr  = dead_read,
 
     .ecp_write_data = dead_write,       /* ecp */
     .ecp_read_data  = dead_read,
     .ecp_write_addr = dead_write,
 
     .compat_write_data  = dead_write,   /* compat */
     .nibble_read_data   = dead_read,    /* nibble */
     .byte_read_data     = dead_read,    /* byte */
 
     .owner      = NULL,
 };
 
 static struct device_type parport_device_type = {
     .name = "parport",
 };
 
 static int is_parport(struct device *dev)
 {
     return dev->type == &parport_device_type;
 }
 
 static int parport_probe(struct device *dev)
 {
     struct parport_driver *drv;
 
     if (is_parport(dev))
         return -ENODEV;
 
     drv = to_parport_driver(dev->driver);
     if (!drv->probe) {
         /* if driver has not defined a custom probe */
         struct pardevice *par_dev = to_pardevice(dev);
 
         if (strcmp(par_dev->name, drv->name))
             return -ENODEV;
         return 0;
     }
     /* if driver defined its own probe */
     return drv->probe(to_pardevice(dev));
 }
 
 static struct bus_type parport_bus_type = {
     .name = "parport",
     .probe = parport_probe,
 };
 
 int parport_bus_init(void)
 {
     return bus_register(&parport_bus_type);
 }
 
 void parport_bus_exit(void)
 {
     bus_unregister(&parport_bus_type);
 }
 
 /*
  * iterates through all the drivers registered with the bus and sends the port
  * details to the match_port callback of the driver, so that the driver can
  * know about the new port that just registered with the bus and decide if it
  * wants to use this new port.
  */
 static int driver_check(struct device_driver *dev_drv, void *_port)
 {
     struct parport *port = _port;
     struct parport_driver *drv = to_parport_driver(dev_drv);
 
     if (drv->match_port)
         drv->match_port(port);
     return 0;
 }
 
 /* Call attach(port) for each registered driver. */
 static void attach_driver_chain(struct parport *port)
 {
     /* caller has exclusive registration_lock */
     struct parport_driver *drv;
 
     list_for_each_entry(drv, &drivers, list)
         drv->attach(port);
 
     /*
      * call the driver_check function of the drivers registered in
      * new device model
      */
 
     bus_for_each_drv(&parport_bus_type, NULL, port, driver_check);
 }
 
 static int driver_detach(struct device_driver *_drv, void *_port)
 {
     struct parport *port = _port;
     struct parport_driver *drv = to_parport_driver(_drv);
 
     if (drv->detach)
         drv->detach(port);
     return 0;
 }
 
 /* Call detach(port) for each registered driver. */
 static void detach_driver_chain(struct parport *port)
 {
     struct parport_driver *drv;
     /* caller has exclusive registration_lock */
     list_for_each_entry(drv, &drivers, list)
         drv->detach(port);
 
     /*
      * call the detach function of the drivers registered in
      * new device model
      */
 
     bus_for_each_drv(&parport_bus_type, NULL, port, driver_detach);
 }
 
 /* Ask kmod for some lowlevel drivers. */
 static void get_lowlevel_driver(void)
 {
     /*
      * There is no actual module called this: you should set
      * up an alias for modutils.
      */
     request_module("parport_lowlevel");
 }
 
 /*
  * iterates through all the devices connected to the bus and sends the device
  * details to the match_port callback of the driver, so that the driver can
  * know what are all the ports that are connected to the bus and choose the
  * port to which it wants to register its device.
  */
 static int port_check(struct device *dev, void *dev_drv)
 {
     struct parport_driver *drv = dev_drv;
 
     /* only send ports, do not send other devices connected to bus */
     if (is_parport(dev))
         drv->match_port(to_parport_dev(dev));
     return 0;
 }
 
 /*
  * Iterates through all the devices connected to the bus and return 1
  * if the device is a parallel port.
  */
 
 static int port_detect(struct device *dev, void *dev_drv)
 {
     if (is_parport(dev))
         return 1;
     return 0;
 }
 
 /**
  *  __parport_register_driver - register a parallel port device driver
  *  @drv: structure describing the driver
  *  @owner: owner module of drv
  *  @mod_name: module name string
  *
  *  This can be called by a parallel port device driver in order
  *  to receive notifications about ports being found in the
  *  system, as well as ports no longer available.
  *
  *  If devmodel is true then the new device model is used
  *  for registration.
  *
  *  The @drv structure is allocated by the caller and must not be
  *  deallocated until after calling parport_unregister_driver().
  *
  *  If using the non device model:
  *  The driver's attach() function may block.  The port that
  *  attach() is given will be valid for the duration of the
  *  callback, but if the driver wants to take a copy of the
  *  pointer it must call parport_get_port() to do so.  Calling
  *  parport_register_device() on that port will do this for you.
  *
  *  The driver's detach() function may block.  The port that
  *  detach() is given will be valid for the duration of the
  *  callback, but if the driver wants to take a copy of the
  *  pointer it must call parport_get_port() to do so.
  *
  *
  *  Returns 0 on success. The non device model will always succeeds.
  *  but the new device model can fail and will return the error code.
  **/
 
 int __parport_register_driver(struct parport_driver *drv, struct module *owner,
                   const char *mod_name)
 {
     /* using device model */
     int ret;
 
     /* initialize common driver fields */
     drv->driver.name = drv->name;
     drv->driver.bus = &parport_bus_type;
     drv->driver.owner = owner;
     drv->driver.mod_name = mod_name;
     ret = driver_register(&drv->driver);
     if (ret)
         return ret;
 
     /*
      * check if bus has any parallel port registered, if
      * none is found then load the lowlevel driver.
      */
     ret = bus_for_each_dev(&parport_bus_type, NULL, NULL,
                    port_detect);
     if (!ret)
         get_lowlevel_driver();
 
     mutex_lock(&registration_lock);
     if (drv->match_port)
         bus_for_each_dev(&parport_bus_type, NULL, drv,
                  port_check);
     mutex_unlock(&registration_lock);
 
     return 0;
 }
 EXPORT_SYMBOL(__parport_register_driver);
 
 static int port_detach(struct device *dev, void *_drv)
 {
     struct parport_driver *drv = _drv;
 
     if (is_parport(dev) && drv->detach)
         drv->detach(to_parport_dev(dev));
 
     return 0;
 }
 
 /**
  *  parport_unregister_driver - deregister a parallel port device driver
  *  @drv: structure describing the driver that was given to
  *        parport_register_driver()
  *
  *  This should be called by a parallel port device driver that
  *  has registered itself using parport_register_driver() when it
  *  is about to be unloaded.
  *
  *  When it returns, the driver's attach() routine will no longer
  *  be called, and for each port that attach() was called for, the
  *  detach() routine will have been called.
  *
  *  All the driver's attach() and detach() calls are guaranteed to have
  *  finished by the time this function returns.
  **/
 
 void parport_unregister_driver(struct parport_driver *drv)
 {
     mutex_lock(&registration_lock);
     bus_for_each_dev(&parport_bus_type, NULL, drv, port_detach);
     driver_unregister(&drv->driver);
     mutex_unlock(&registration_lock);
 }
 EXPORT_SYMBOL(parport_unregister_driver);
 
 static void free_port(struct device *dev)
 {
     int d;
     struct parport *port = to_parport_dev(dev);
 
     spin_lock(&full_list_lock);
     list_del(&port->full_list);
     spin_unlock(&full_list_lock);
     for (d = 0; d < 5; d++) {
         kfree(port->probe_info[d].class_name);
         kfree(port->probe_info[d].mfr);
         kfree(port->probe_info[d].model);
         kfree(port->probe_info[d].cmdset);
         kfree(port->probe_info[d].description);
     }
 
     kfree(port->name);
     kfree(port);
 }
 
 /**
  *  parport_get_port - increment a port's reference count
  *  @port: the port
  *
  *  This ensures that a struct parport pointer remains valid
  *  until the matching parport_put_port() call.
  **/
 
 struct parport *parport_get_port(struct parport *port)
 {
     struct device *dev = get_device(&port->bus_dev);
 
     return to_parport_dev(dev);
 }
 EXPORT_SYMBOL(parport_get_port);
 
 void parport_del_port(struct parport *port)
 {
     device_unregister(&port->bus_dev);
 }
 EXPORT_SYMBOL(parport_del_port);
 
 /**
  *  parport_put_port - decrement a port's reference count
  *  @port: the port
  *
  *  This should be called once for each call to parport_get_port(),
  *  once the port is no longer needed. When the reference count reaches
  *  zero (port is no longer used), free_port is called.
  **/
 
 void parport_put_port(struct parport *port)
 {
     put_device(&port->bus_dev);
 }
 EXPORT_SYMBOL(parport_put_port);
 
 /**
  *  parport_register_port - register a parallel port
  *  @base: base I/O address
  *  @irq: IRQ line
  *  @dma: DMA channel
  *  @ops: pointer to the port driver's port operations structure
  *
  *  When a parallel port (lowlevel) driver finds a port that
  *  should be made available to parallel port device drivers, it
  *  should call parport_register_port().  The @base, @irq, and
  *  @dma parameters are for the convenience of port drivers, and
  *  for ports where they aren't meaningful needn't be set to
  *  anything special.  They can be altered afterwards by adjusting
  *  the relevant members of the parport structure that is returned
  *  and represents the port.  They should not be tampered with
  *  after calling parport_announce_port, however.
  *
  *  If there are parallel port device drivers in the system that
  *  have registered themselves using parport_register_driver(),
  *  they are not told about the port at this time; that is done by
  *  parport_announce_port().
  *
  *  The @ops structure is allocated by the caller, and must not be
  *  deallocated before calling parport_remove_port().
  *
  *  If there is no memory to allocate a new parport structure,
  *  this function will return %NULL.
  **/
 
 struct parport *parport_register_port(unsigned long base, int irq, int dma,
                       struct parport_operations *ops)
 {
     struct list_head *l;
     struct parport *tmp;
     int num;
     int device;
     char *name;
     int ret;
 
     tmp = kzalloc(sizeof(struct parport), GFP_KERNEL);
     if (!tmp)
         return NULL;
 
     /* Init our structure */
     tmp->base = base;
     tmp->irq = irq;
     tmp->dma = dma;
     tmp->muxport = tmp->daisy = tmp->muxsel = -1;
     tmp->modes = 0;
     INIT_LIST_HEAD(&tmp->list);
     tmp->devices = tmp->cad = NULL;
     tmp->flags = 0;
     tmp->ops = ops;
     tmp->physport = tmp;
     memset(tmp->probe_info, 0, 5 * sizeof(struct parport_device_info));
     rwlock_init(&tmp->cad_lock);
     spin_lock_init(&tmp->waitlist_lock);
     spin_lock_init(&tmp->pardevice_lock);
     tmp->ieee1284.mode = IEEE1284_MODE_COMPAT;
     tmp->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
     sema_init(&tmp->ieee1284.irq, 0);
     tmp->spintime = parport_default_spintime;
     atomic_set(&tmp->ref_count, 1);
     INIT_LIST_HEAD(&tmp->full_list);
 
     name = kmalloc(15, GFP_KERNEL);
     if (!name) {
         kfree(tmp);
         return NULL;
     }
     /* Search for the lowest free parport number. */
 
     spin_lock(&full_list_lock);
     for (l = all_ports.next, num = 0; l != &all_ports; l = l->next, num++) {
         struct parport *p = list_entry(l, struct parport, full_list);
         if (p->number != num)
             break;
     }
     tmp->portnum = tmp->number = num;
     list_add_tail(&tmp->full_list, l);
     spin_unlock(&full_list_lock);
 
     /*
      * Now that the portnum is known finish doing the Init.
      */
     sprintf(name, "parport%d", tmp->portnum = tmp->number);
     tmp->name = name;
     tmp->bus_dev.bus = &parport_bus_type;
     tmp->bus_dev.release = free_port;
     dev_set_name(&tmp->bus_dev, name);
     tmp->bus_dev.type = &parport_device_type;
 
     for (device = 0; device < 5; device++)
         /* assume the worst */
         tmp->probe_info[device].class = PARPORT_CLASS_LEGACY;
 
     tmp->waithead = tmp->waittail = NULL;
 
     ret = device_register(&tmp->bus_dev);
     if (ret) {
         put_device(&tmp->bus_dev);
         return NULL;
     }
 
     return tmp;
 }
 EXPORT_SYMBOL(parport_register_port);
 
 /**
  *  parport_announce_port - tell device drivers about a parallel port
  *  @port: parallel port to announce
  *
  *  After a port driver has registered a parallel port with
  *  parport_register_port, and performed any necessary
  *  initialisation or adjustments, it should call
  *  parport_announce_port() in order to notify all device drivers
  *  that have called parport_register_driver().  Their attach()
  *  functions will be called, with @port as the parameter.
  **/
 
 void parport_announce_port(struct parport *port)
 {
     int i;
 
 #ifdef CONFIG_PARPORT_1284
     /* Analyse the IEEE1284.3 topology of the port. */
     parport_daisy_init(port);
 #endif
 
     if (!port->dev)
         pr_warn("%s: fix this legacy no-device port driver!\n",
             port->name);
 
     parport_proc_register(port);
     mutex_lock(&registration_lock);
     spin_lock_irq(&parportlist_lock);
     list_add_tail(&port->list, &portlist);
     for (i = 1; i < 3; i++) {
         struct parport *slave = port->slaves[i-1];
         if (slave)
             list_add_tail(&slave->list, &portlist);
     }
     spin_unlock_irq(&parportlist_lock);
 
     /* Let drivers know that new port(s) has arrived. */
     attach_driver_chain(port);
     for (i = 1; i < 3; i++) {
         struct parport *slave = port->slaves[i-1];
         if (slave)
             attach_driver_chain(slave);
     }
     mutex_unlock(&registration_lock);
 }
 EXPORT_SYMBOL(parport_announce_port);
 
 /**
  *  parport_remove_port - deregister a parallel port
  *  @port: parallel port to deregister
  *
  *  When a parallel port driver is forcibly unloaded, or a
  *  parallel port becomes inaccessible, the port driver must call
  *  this function in order to deal with device drivers that still
  *  want to use it.
  *
  *  The parport structure associated with the port has its
  *  operations structure replaced with one containing 'null'
  *  operations that return errors or just don't do anything.
  *
  *  Any drivers that have registered themselves using
  *  parport_register_driver() are notified that the port is no
  *  longer accessible by having their detach() routines called
  *  with @port as the parameter.
  **/
 
 void parport_remove_port(struct parport *port)
 {
     int i;
 
     mutex_lock(&registration_lock);
 
     /* Spread the word. */
     detach_driver_chain(port);
 
 #ifdef CONFIG_PARPORT_1284
     /* Forget the IEEE1284.3 topology of the port. */
     parport_daisy_fini(port);
     for (i = 1; i < 3; i++) {
         struct parport *slave = port->slaves[i-1];
         if (!slave)
             continue;
         detach_driver_chain(slave);
         parport_daisy_fini(slave);
     }
 #endif
 
     port->ops = &dead_ops;
     spin_lock(&parportlist_lock);
     list_del_init(&port->list);
     for (i = 1; i < 3; i++) {
         struct parport *slave = port->slaves[i-1];
         if (slave)
             list_del_init(&slave->list);
     }
     spin_unlock(&parportlist_lock);
 
     mutex_unlock(&registration_lock);
 
     parport_proc_unregister(port);
 
     for (i = 1; i < 3; i++) {
         struct parport *slave = port->slaves[i-1];
         if (slave)
             parport_put_port(slave);
     }
 }
 EXPORT_SYMBOL(parport_remove_port);
 
 static void free_pardevice(struct device *dev)
 {
     struct pardevice *par_dev = to_pardevice(dev);
 
     kfree(par_dev->name);
     kfree(par_dev);
 }
 
 /**
  *  parport_register_dev_model - register a device on a parallel port
  *  @port: port to which the device is attached
  *  @name: a name to refer to the device
  *  @par_dev_cb: struct containing callbacks
  *  @id: device number to be given to the device
  *
  *  This function, called by parallel port device drivers,
  *  declares that a device is connected to a port, and tells the
  *  system all it needs to know.
  *
  *  The struct pardev_cb contains pointer to callbacks. preemption
  *  callback function, @preempt, is called when this device driver
  *  has claimed access to the port but another device driver wants
  *  to use it.  It is given, @private, as its parameter, and should
  *  return zero if it is willing for the system to release the port
  *  to another driver on its behalf. If it wants to keep control of
  *  the port it should return non-zero, and no action will be taken.
  *  It is good manners for the driver to try to release the port at
  *  the earliest opportunity after its preemption callback rejects a
  *  preemption attempt. Note that if a preemption callback is happy
  *  for preemption to go ahead, there is no need to release the
  *  port; it is done automatically. This function may not block, as
  *  it may be called from interrupt context. If the device driver
  *  does not support preemption, @preempt can be %NULL.
  *
  *  The wake-up ("kick") callback function, @wakeup, is called when
  *  the port is available to be claimed for exclusive access; that
  *  is, parport_claim() is guaranteed to succeed when called from
  *  inside the wake-up callback function.  If the driver wants to
  *  claim the port it should do so; otherwise, it need not take
  *  any action.  This function may not block, as it may be called
  *  from interrupt context.  If the device driver does not want to
  *  be explicitly invited to claim the port in this way, @wakeup can
  *  be %NULL.
  *
  *  The interrupt handler, @irq_func, is called when an interrupt
  *  arrives from the parallel port.  Note that if a device driver
  *  wants to use interrupts it should use parport_enable_irq(),
  *  and can also check the irq member of the parport structure
  *  representing the port.
  *
  *  The parallel port (lowlevel) driver is the one that has called
  *  request_irq() and whose interrupt handler is called first.
  *  This handler does whatever needs to be done to the hardware to
  *  acknowledge the interrupt (for PC-style ports there is nothing
  *  special to be done).  It then tells the IEEE 1284 code about
  *  the interrupt, which may involve reacting to an IEEE 1284
  *  event depending on the current IEEE 1284 phase.  After this,
  *  it calls @irq_func.  Needless to say, @irq_func will be called
  *  from interrupt context, and may not block.
  *
  *  The %PARPORT_DEV_EXCL flag is for preventing port sharing, and
  *  so should only be used when sharing the port with other device
  *  drivers is impossible and would lead to incorrect behaviour.
  *  Use it sparingly!  Normally, @flags will be zero.
  *
  *  This function returns a pointer to a structure that represents
  *  the device on the port, or %NULL if there is not enough memory
  *  to allocate space for that structure.
  **/
 
 struct pardevice *
 parport_register_dev_model(struct parport *port, const char *name,
                const struct pardev_cb *par_dev_cb, int id)
 {
     struct pardevice *par_dev;
     int ret;
     char *devname;
 
     if (port->physport->flags & PARPORT_FLAG_EXCL) {
         /* An exclusive device is registered. */
         pr_err("%s: no more devices allowed\n", port->name);
         return NULL;
     }
 
     if (par_dev_cb->flags & PARPORT_DEV_LURK) {
         if (!par_dev_cb->preempt || !par_dev_cb->wakeup) {
             pr_info("%s: refused to register lurking device (%s) without callbacks\n",
                 port->name, name);
             return NULL;
         }
     }
 
     if (par_dev_cb->flags & PARPORT_DEV_EXCL) {
         if (port->physport->devices) {
             /*
              * If a device is already registered and this new
              * device wants exclusive access, then no need to
              * continue as we can not grant exclusive access to
              * this device.
              */
             pr_err("%s: cannot grant exclusive access for device %s\n",
                    port->name, name);
             return NULL;
         }
     }
 
     if (!try_module_get(port->ops->owner))
         return NULL;
 
     parport_get_port(port);
 
     par_dev = kzalloc(sizeof(*par_dev), GFP_KERNEL);
     if (!par_dev)
         goto err_put_port;
 
     par_dev->state = kzalloc(sizeof(*par_dev->state), GFP_KERNEL);
     if (!par_dev->state)
         goto err_put_par_dev;
 
     devname = kstrdup(name, GFP_KERNEL);
     if (!devname)
         goto err_free_par_dev;
 
     par_dev->name = devname;
     par_dev->port = port;
     par_dev->daisy = -1;
     par_dev->preempt = par_dev_cb->preempt;
     par_dev->wakeup = par_dev_cb->wakeup;
     par_dev->private = par_dev_cb->private;
     par_dev->flags = par_dev_cb->flags;
     par_dev->irq_func = par_dev_cb->irq_func;
     par_dev->waiting = 0;
     par_dev->timeout = 5 * HZ;
 
     par_dev->dev.parent = &port->bus_dev;
     par_dev->dev.bus = &parport_bus_type;
     ret = dev_set_name(&par_dev->dev, "%s.%d", devname, id);
     if (ret)
         goto err_free_devname;
     par_dev->dev.release = free_pardevice;
     par_dev->devmodel = true;
     ret = device_register(&par_dev->dev);
     if (ret) {
         kfree(par_dev->state);
         put_device(&par_dev->dev);
         goto err_put_port;
     }
 
     /* Chain this onto the list */
     par_dev->prev = NULL;
     /*
      * This function must not run from an irq handler so we don' t need
      * to clear irq on the local CPU. -arca
      */
     spin_lock(&port->physport->pardevice_lock);
 
     if (par_dev_cb->flags & PARPORT_DEV_EXCL) {
         if (port->physport->devices) {
             spin_unlock(&port->physport->pardevice_lock);
             pr_debug("%s: cannot grant exclusive access for device %s\n",
                  port->name, name);
             kfree(par_dev->state);
             device_unregister(&par_dev->dev);
             goto err_put_port;
         }
         port->flags |= PARPORT_FLAG_EXCL;
     }
 
     par_dev->next = port->physport->devices;
     wmb();  /*
          * Make sure that tmp->next is written before it's
          * added to the list; see comments marked 'no locking
          * required'
          */
     if (port->physport->devices)
         port->physport->devices->prev = par_dev;
     port->physport->devices = par_dev;
     spin_unlock(&port->physport->pardevice_lock);
 
     init_waitqueue_head(&par_dev->wait_q);
     par_dev->timeslice = parport_default_timeslice;
     par_dev->waitnext = NULL;
     par_dev->waitprev = NULL;
 
     /*
      * This has to be run as last thing since init_state may need other
      * pardevice fields. -arca
      */
     port->ops->init_state(par_dev, par_dev->state);
     if (!test_and_set_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags)) {
         port->proc_device = par_dev;
         parport_device_proc_register(par_dev);
     }
 
     return par_dev;
 
 err_free_devname:
     kfree(devname);
 err_free_par_dev:
     kfree(par_dev->state);
 err_put_par_dev:
     if (!par_dev->devmodel)
         kfree(par_dev);
 err_put_port:
     parport_put_port(port);
     module_put(port->ops->owner);
 
     return NULL;
 }
 EXPORT_SYMBOL(parport_register_dev_model);
 
 /**
  *  parport_unregister_device - deregister a device on a parallel port
  *  @dev: pointer to structure representing device
  *
  *  This undoes the effect of parport_register_device().
  **/
 
 void parport_unregister_device(struct pardevice *dev)
 {
     struct parport *port;
 
 #ifdef PARPORT_PARANOID
     if (!dev) {
         pr_err("%s: passed NULL\n", __func__);
         return;
     }
 #endif
 
     port = dev->port->physport;
 
     if (port->proc_device == dev) {
         port->proc_device = NULL;
         clear_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags);
         parport_device_proc_unregister(dev);
     }
 
     if (port->cad == dev) {
         printk(KERN_DEBUG "%s: %s forgot to release port\n",
                port->name, dev->name);
         parport_release(dev);
     }
 
     spin_lock(&port->pardevice_lock);
     if (dev->next)
         dev->next->prev = dev->prev;
     if (dev->prev)
         dev->prev->next = dev->next;
     else
         port->devices = dev->next;
 
     if (dev->flags & PARPORT_DEV_EXCL)
         port->flags &= ~PARPORT_FLAG_EXCL;
 
     spin_unlock(&port->pardevice_lock);
 
     /*
      * Make sure we haven't left any pointers around in the wait
      * list.
      */
     spin_lock_irq(&port->waitlist_lock);
     if (dev->waitprev || dev->waitnext || port->waithead == dev) {
         if (dev->waitprev)
             dev->waitprev->waitnext = dev->waitnext;
         else
             port->waithead = dev->waitnext;
         if (dev->waitnext)
             dev->waitnext->waitprev = dev->waitprev;
         else
             port->waittail = dev->waitprev;
     }
     spin_unlock_irq(&port->waitlist_lock);
 
     kfree(dev->state);
     device_unregister(&dev->dev);
 
     module_put(port->ops->owner);
     parport_put_port(port);
 }
 EXPORT_SYMBOL(parport_unregister_device);
 
 /**
  *  parport_find_number - find a parallel port by number
  *  @number: parallel port number
  *
  *  This returns the parallel port with the specified number, or
  *  %NULL if there is none.
  *
  *  There is an implicit parport_get_port() done already; to throw
  *  away the reference to the port that parport_find_number()
  *  gives you, use parport_put_port().
  */
 
 struct parport *parport_find_number(int number)
 {
     struct parport *port, *result = NULL;
 
     if (list_empty(&portlist))
         get_lowlevel_driver();
 
     spin_lock(&parportlist_lock);
     list_for_each_entry(port, &portlist, list) {
         if (port->number == number) {
             result = parport_get_port(port);
             break;
         }
     }
     spin_unlock(&parportlist_lock);
     return result;
 }
 EXPORT_SYMBOL(parport_find_number);
 
 /**
  *  parport_find_base - find a parallel port by base address
  *  @base: base I/O address
  *
  *  This returns the parallel port with the specified base
  *  address, or %NULL if there is none.
  *
  *  There is an implicit parport_get_port() done already; to throw
  *  away the reference to the port that parport_find_base()
  *  gives you, use parport_put_port().
  */
 
 struct parport *parport_find_base(unsigned long base)
 {
     struct parport *port, *result = NULL;
 
     if (list_empty(&portlist))
         get_lowlevel_driver();
 
     spin_lock(&parportlist_lock);
     list_for_each_entry(port, &portlist, list) {
         if (port->base == base) {
             result = parport_get_port(port);
             break;
         }
     }
     spin_unlock(&parportlist_lock);
     return result;
 }
 EXPORT_SYMBOL(parport_find_base);
 
 /**
  *  parport_claim - claim access to a parallel port device
  *  @dev: pointer to structure representing a device on the port
  *
  *  This function will not block and so can be used from interrupt
  *  context.  If parport_claim() succeeds in claiming access to
  *  the port it returns zero and the port is available to use.  It
  *  may fail (returning non-zero) if the port is in use by another
  *  driver and that driver is not willing to relinquish control of
  *  the port.
  **/
 
 int parport_claim(struct pardevice *dev)
 {
     struct pardevice *oldcad;
     struct parport *port = dev->port->physport;
     unsigned long flags;
 
     if (port->cad == dev) {
         pr_info("%s: %s already owner\n", dev->port->name, dev->name);
         return 0;
     }
 
     /* Preempt any current device */
     write_lock_irqsave(&port->cad_lock, flags);
     oldcad = port->cad;
     if (oldcad) {
         if (oldcad->preempt) {
             if (oldcad->preempt(oldcad->private))
                 goto blocked;
             port->ops->save_state(port, dev->state);
         } else
             goto blocked;
 
         if (port->cad != oldcad) {
             /*
              * I think we'll actually deadlock rather than
              * get here, but just in case..
              */
             pr_warn("%s: %s released port when preempted!\n",
                 port->name, oldcad->name);
             if (port->cad)
                 goto blocked;
         }
     }
 
     /* Can't fail from now on, so mark ourselves as no longer waiting.  */
     if (dev->waiting & 1) {
         dev->waiting = 0;
 
         /* Take ourselves out of the wait list again.  */
         spin_lock_irq(&port->waitlist_lock);
         if (dev->waitprev)
             dev->waitprev->waitnext = dev->waitnext;
         else
             port->waithead = dev->waitnext;
         if (dev->waitnext)
             dev->waitnext->waitprev = dev->waitprev;
         else
             port->waittail = dev->waitprev;
         spin_unlock_irq(&port->waitlist_lock);
         dev->waitprev = dev->waitnext = NULL;
     }
 
     /* Now we do the change of devices */
     port->cad = dev;
 
 #ifdef CONFIG_PARPORT_1284
     /* If it's a mux port, select it. */
     if (dev->port->muxport >= 0) {
         /* FIXME */
         port->muxsel = dev->port->muxport;
     }
 
     /* If it's a daisy chain device, select it. */
     if (dev->daisy >= 0) {
         /* This could be lazier. */
         if (!parport_daisy_select(port, dev->daisy,
                        IEEE1284_MODE_COMPAT))
             port->daisy = dev->daisy;
     }
 #endif /* IEEE1284.3 support */
 
     /* Restore control registers */
     port->ops->restore_state(port, dev->state);
     write_unlock_irqrestore(&port->cad_lock, flags);
     dev->time = jiffies;
     return 0;
 
 blocked:
     /*
      * If this is the first time we tried to claim the port, register an
      * interest.  This is only allowed for devices sleeping in
      * parport_claim_or_block(), or those with a wakeup function.
      */
 
     /* The cad_lock is still held for writing here */
     if (dev->waiting & 2 || dev->wakeup) {
         spin_lock(&port->waitlist_lock);
         if (test_and_set_bit(0, &dev->waiting) == 0) {
             /* First add ourselves to the end of the wait list. */
             dev->waitnext = NULL;
             dev->waitprev = port->waittail;
             if (port->waittail) {
                 port->waittail->waitnext = dev;
                 port->waittail = dev;
             } else
                 port->waithead = port->waittail = dev;
         }
         spin_unlock(&port->waitlist_lock);
     }
     write_unlock_irqrestore(&port->cad_lock, flags);
     return -EAGAIN;
 }
 EXPORT_SYMBOL(parport_claim);
 
 /**
  *  parport_claim_or_block - claim access to a parallel port device
  *  @dev: pointer to structure representing a device on the port
  *
  *  This behaves like parport_claim(), but will block if necessary
  *  to wait for the port to be free.  A return value of 1
  *  indicates that it slept; 0 means that it succeeded without
  *  needing to sleep.  A negative error code indicates failure.
  **/
 
 int parport_claim_or_block(struct pardevice *dev)
 {
     int r;
 
     /*
      * Signal to parport_claim() that we can wait even without a
      * wakeup function.
      */
     dev->waiting = 2;
 
     /* Try to claim the port.  If this fails, we need to sleep.  */
     r = parport_claim(dev);
     if (r == -EAGAIN) {
 #ifdef PARPORT_DEBUG_SHARING
         printk(KERN_DEBUG "%s: parport_claim() returned -EAGAIN\n",
                dev->name);
 #endif
         /*
          * FIXME!!! Use the proper locking for dev->waiting,
          * and make this use the "wait_event_interruptible()"
          * interfaces. The cli/sti that used to be here
          * did nothing.
          *
          * See also parport_release()
          */
 
         /*
          * If dev->waiting is clear now, an interrupt
          * gave us the port and we would deadlock if we slept.
          */
         if (dev->waiting) {
             wait_event_interruptible(dev->wait_q,
                          !dev->waiting);
             if (signal_pending(current))
                 return -EINTR;
             r = 1;
         } else {
             r = 0;
 #ifdef PARPORT_DEBUG_SHARING
             printk(KERN_DEBUG "%s: didn't sleep in parport_claim_or_block()\n",
                    dev->name);
 #endif
         }
 
 #ifdef PARPORT_DEBUG_SHARING
         if (dev->port->physport->cad != dev)
             printk(KERN_DEBUG "%s: exiting parport_claim_or_block but %s owns port!\n",
                    dev->name, dev->port->physport->cad ?
                    dev->port->physport->cad->name : "nobody");
 #endif
     }
     dev->waiting = 0;
     return r;
 }
 EXPORT_SYMBOL(parport_claim_or_block);
 
 /**
  *  parport_release - give up access to a parallel port device
  *  @dev: pointer to structure representing parallel port device
  *
  *  This function cannot fail, but it should not be called without
  *  the port claimed.  Similarly, if the port is already claimed
  *  you should not try claiming it again.
  **/
 
 void parport_release(struct pardevice *dev)
 {
     struct parport *port = dev->port->physport;
     struct pardevice *pd;
     unsigned long flags;
 
     /* Make sure that dev is the current device */
     write_lock_irqsave(&port->cad_lock, flags);
     if (port->cad != dev) {
         write_unlock_irqrestore(&port->cad_lock, flags);
         pr_warn("%s: %s tried to release parport when not owner\n",
             port->name, dev->name);
         return;
     }
 
 #ifdef CONFIG_PARPORT_1284
     /* If this is on a mux port, deselect it. */
     if (dev->port->muxport >= 0) {
         /* FIXME */
         port->muxsel = -1;
     }
 
     /* If this is a daisy device, deselect it. */
     if (dev->daisy >= 0) {
         parport_daisy_deselect_all(port);
         port->daisy = -1;
     }
 #endif
 
     port->cad = NULL;
     write_unlock_irqrestore(&port->cad_lock, flags);
 
     /* Save control registers */
     port->ops->save_state(port, dev->state);
 
     /*
      * If anybody is waiting, find out who's been there longest and
      * then wake them up. (Note: no locking required)
      */
     /* !!! LOCKING IS NEEDED HERE */
     for (pd = port->waithead; pd; pd = pd->waitnext) {
         if (pd->waiting & 2) { /* sleeping in claim_or_block */
             parport_claim(pd);
             if (waitqueue_active(&pd->wait_q))
                 wake_up_interruptible(&pd->wait_q);
             return;
         } else if (pd->wakeup) {
             pd->wakeup(pd->private);
             if (dev->port->cad) /* racy but no matter */
                 return;
         } else {
             pr_err("%s: don't know how to wake %s\n",
                    port->name, pd->name);
         }
     }
 
     /*
      * Nobody was waiting, so walk the list to see if anyone is
      * interested in being woken up. (Note: no locking required)
      */
     /* !!! LOCKING IS NEEDED HERE */
     for (pd = port->devices; !port->cad && pd; pd = pd->next) {
         if (pd->wakeup && pd != dev)
             pd->wakeup(pd->private);
     }
 }
 EXPORT_SYMBOL(parport_release);
 
 irqreturn_t parport_irq_handler(int irq, void *dev_id)
 {
     struct parport *port = dev_id;
 
     parport_generic_irq(port);
 
     return IRQ_HANDLED;
 }
 EXPORT_SYMBOL(parport_irq_handler);
 
 MODULE_LICENSE("GPL");

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