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 // SPDX-License-Identifier: GPL-2.0
 /*
  * z/VM IUCV hypervisor console (HVC) device driver
  *
  * This HVC device driver provides terminal access using
  * z/VM IUCV communication paths.
  *
  * Copyright IBM Corp. 2008, 2013
  *
  * Author(s):   Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
  */
 #define KMSG_COMPONENT      "hvc_iucv"
 #define pr_fmt(fmt)     KMSG_COMPONENT ": " fmt
 
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <asm/ebcdic.h>
 #include <linux/ctype.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/mempool.h>
 #include <linux/moduleparam.h>
 #include <linux/tty.h>
 #include <linux/wait.h>
 #include <net/iucv/iucv.h>
 
 #include "hvc_console.h"
 
 
 /* General device driver settings */
 #define HVC_IUCV_MAGIC      0xc9e4c3e5
 #define MAX_HVC_IUCV_LINES  HVC_ALLOC_TTY_ADAPTERS
 #define MEMPOOL_MIN_NR      (PAGE_SIZE / sizeof(struct iucv_tty_buffer)/4)
 
 /* IUCV TTY message  */
 #define MSG_VERSION     0x02    /* Message version */
 #define MSG_TYPE_ERROR      0x01    /* Error message */
 #define MSG_TYPE_TERMENV    0x02    /* Terminal environment variable */
 #define MSG_TYPE_TERMIOS    0x04    /* Terminal IO struct update */
 #define MSG_TYPE_WINSIZE    0x08    /* Terminal window size update */
 #define MSG_TYPE_DATA       0x10    /* Terminal data */
 
 struct iucv_tty_msg {
     u8  version;        /* Message version */
     u8  type;           /* Message type */
 #define MSG_MAX_DATALEN     ((u16)(~0))
     u16 datalen;        /* Payload length */
     u8  data[];         /* Payload buffer */
 } __attribute__((packed));
 #define MSG_SIZE(s)     ((s) + offsetof(struct iucv_tty_msg, data))
 
 enum iucv_state_t {
     IUCV_DISCONN    = 0,
     IUCV_CONNECTED  = 1,
     IUCV_SEVERED    = 2,
 };
 
 enum tty_state_t {
     TTY_CLOSED  = 0,
     TTY_OPENED  = 1,
 };
 
 struct hvc_iucv_private {
     struct hvc_struct   *hvc;       /* HVC struct reference */
     u8          srv_name[8];    /* IUCV service name (ebcdic) */
     unsigned char       is_console; /* Linux console usage flag */
     enum iucv_state_t   iucv_state; /* IUCV connection status */
     enum tty_state_t    tty_state;  /* TTY status */
     struct iucv_path    *path;      /* IUCV path pointer */
     spinlock_t      lock;       /* hvc_iucv_private lock */
 #define SNDBUF_SIZE     (PAGE_SIZE) /* must be < MSG_MAX_DATALEN */
     void            *sndbuf;    /* send buffer        */
     size_t          sndbuf_len; /* length of send buffer  */
 #define QUEUE_SNDBUF_DELAY  (HZ / 25)
     struct delayed_work sndbuf_work;    /* work: send iucv msg(s) */
     wait_queue_head_t   sndbuf_waitq;   /* wait for send completion */
     struct list_head    tty_outqueue;   /* outgoing IUCV messages */
     struct list_head    tty_inqueue;    /* incoming IUCV messages */
     struct device       *dev;       /* device structure */
     u8          info_path[16];  /* IUCV path info (dev attr) */
 };
 
 struct iucv_tty_buffer {
     struct list_head    list;   /* list pointer */
     struct iucv_message msg;    /* store an IUCV message */
     size_t          offset; /* data buffer offset */
     struct iucv_tty_msg *mbuf;  /* buffer to store input/output data */
 };
 
 /* IUCV callback handler */
 static  int hvc_iucv_path_pending(struct iucv_path *, u8 *, u8 *);
 static void hvc_iucv_path_severed(struct iucv_path *, u8 *);
 static void hvc_iucv_msg_pending(struct iucv_path *, struct iucv_message *);
 static void hvc_iucv_msg_complete(struct iucv_path *, struct iucv_message *);
 
 
 /* Kernel module parameter: use one terminal device as default */
 static unsigned long hvc_iucv_devices = 1;
 
 /* Array of allocated hvc iucv tty lines... */
 static struct hvc_iucv_private *hvc_iucv_table[MAX_HVC_IUCV_LINES];
 #define IUCV_HVC_CON_IDX    (0)
 /* List of z/VM user ID filter entries (struct iucv_vmid_filter) */
 #define MAX_VMID_FILTER     (500)
 #define FILTER_WILDCARD_CHAR    '*'
 static size_t hvc_iucv_filter_size;
 static void *hvc_iucv_filter;
 static const char *hvc_iucv_filter_string;
 static DEFINE_RWLOCK(hvc_iucv_filter_lock);
 
 /* Kmem cache and mempool for iucv_tty_buffer elements */
 static struct kmem_cache *hvc_iucv_buffer_cache;
 static mempool_t *hvc_iucv_mempool;
 
 /* IUCV handler callback functions */
 static struct iucv_handler hvc_iucv_handler = {
     .path_pending  = hvc_iucv_path_pending,
     .path_severed  = hvc_iucv_path_severed,
     .message_complete = hvc_iucv_msg_complete,
     .message_pending  = hvc_iucv_msg_pending,
 };
 
 
 /**
  * hvc_iucv_get_private() - Return a struct hvc_iucv_private instance.
  * @num:    The HVC virtual terminal number (vtermno)
  *
  * This function returns the struct hvc_iucv_private instance that corresponds
  * to the HVC virtual terminal number specified as parameter @num.
  */
 static struct hvc_iucv_private *hvc_iucv_get_private(uint32_t num)
 {
     if ((num < HVC_IUCV_MAGIC) || (num - HVC_IUCV_MAGIC > hvc_iucv_devices))
         return NULL;
     return hvc_iucv_table[num - HVC_IUCV_MAGIC];
 }
 
 /**
  * alloc_tty_buffer() - Return a new struct iucv_tty_buffer element.
  * @size:   Size of the internal buffer used to store data.
  * @flags:  Memory allocation flags passed to mempool.
  *
  * This function allocates a new struct iucv_tty_buffer element and, optionally,
  * allocates an internal data buffer with the specified size @size.
  * The internal data buffer is always allocated with GFP_DMA which is
  * required for receiving and sending data with IUCV.
  * Note: The total message size arises from the internal buffer size and the
  *   members of the iucv_tty_msg structure.
  * The function returns NULL if memory allocation has failed.
  */
 static struct iucv_tty_buffer *alloc_tty_buffer(size_t size, gfp_t flags)
 {
     struct iucv_tty_buffer *bufp;
 
     bufp = mempool_alloc(hvc_iucv_mempool, flags);
     if (!bufp)
         return NULL;
     memset(bufp, 0, sizeof(*bufp));
 
     if (size > 0) {
         bufp->msg.length = MSG_SIZE(size);
         bufp->mbuf = kmalloc(bufp->msg.length, flags | GFP_DMA);
         if (!bufp->mbuf) {
             mempool_free(bufp, hvc_iucv_mempool);
             return NULL;
         }
         bufp->mbuf->version = MSG_VERSION;
         bufp->mbuf->type    = MSG_TYPE_DATA;
         bufp->mbuf->datalen = (u16) size;
     }
     return bufp;
 }
 
 /**
  * destroy_tty_buffer() - destroy struct iucv_tty_buffer element.
  * @bufp:   Pointer to a struct iucv_tty_buffer element, SHALL NOT be NULL.
  */
 static void destroy_tty_buffer(struct iucv_tty_buffer *bufp)
 {
     kfree(bufp->mbuf);
     mempool_free(bufp, hvc_iucv_mempool);
 }
 
 /**
  * destroy_tty_buffer_list() - call destroy_tty_buffer() for each list element.
  * @list:   List containing struct iucv_tty_buffer elements.
  */
 static void destroy_tty_buffer_list(struct list_head *list)
 {
     struct iucv_tty_buffer *ent, *next;
 
     list_for_each_entry_safe(ent, next, list, list) {
         list_del(&ent->list);
         destroy_tty_buffer(ent);
     }
 }
 
 /**
  * hvc_iucv_write() - Receive IUCV message & write data to HVC buffer.
  * @priv:       Pointer to struct hvc_iucv_private
  * @buf:        HVC buffer for writing received terminal data.
  * @count:      HVC buffer size.
  * @has_more_data:  Pointer to an int variable.
  *
  * The function picks up pending messages from the input queue and receives
  * the message data that is then written to the specified buffer @buf.
  * If the buffer size @count is less than the data message size, the
  * message is kept on the input queue and @has_more_data is set to 1.
  * If all message data has been written, the message is removed from
  * the input queue.
  *
  * The function returns the number of bytes written to the terminal, zero if
  * there are no pending data messages available or if there is no established
  * IUCV path.
  * If the IUCV path has been severed, then -EPIPE is returned to cause a
  * hang up (that is issued by the HVC layer).
  */
 static int hvc_iucv_write(struct hvc_iucv_private *priv,
               char *buf, int count, int *has_more_data)
 {
     struct iucv_tty_buffer *rb;
     int written;
     int rc;
 
     /* immediately return if there is no IUCV connection */
     if (priv->iucv_state == IUCV_DISCONN)
         return 0;
 
     /* if the IUCV path has been severed, return -EPIPE to inform the
      * HVC layer to hang up the tty device. */
     if (priv->iucv_state == IUCV_SEVERED)
         return -EPIPE;
 
     /* check if there are pending messages */
     if (list_empty(&priv->tty_inqueue))
         return 0;
 
     /* receive an iucv message and flip data to the tty (ldisc) */
     rb = list_first_entry(&priv->tty_inqueue, struct iucv_tty_buffer, list);
 
     written = 0;
     if (!rb->mbuf) { /* message not yet received ... */
         /* allocate mem to store msg data; if no memory is available
          * then leave the buffer on the list and re-try later */
         rb->mbuf = kmalloc(rb->msg.length, GFP_ATOMIC | GFP_DMA);
         if (!rb->mbuf)
             return -ENOMEM;
 
         rc = __iucv_message_receive(priv->path, &rb->msg, 0,
                         rb->mbuf, rb->msg.length, NULL);
         switch (rc) {
         case 0: /* Successful       */
             break;
         case 2: /* No message found */
         case 9: /* Message purged   */
             break;
         default:
             written = -EIO;
         }
         /* remove buffer if an error has occurred or received data
          * is not correct */
         if (rc || (rb->mbuf->version != MSG_VERSION) ||
               (rb->msg.length    != MSG_SIZE(rb->mbuf->datalen)))
             goto out_remove_buffer;
     }
 
     switch (rb->mbuf->type) {
     case MSG_TYPE_DATA:
         written = min_t(int, rb->mbuf->datalen - rb->offset, count);
         memcpy(buf, rb->mbuf->data + rb->offset, written);
         if (written < (rb->mbuf->datalen - rb->offset)) {
             rb->offset += written;
             *has_more_data = 1;
             goto out_written;
         }
         break;
 
     case MSG_TYPE_WINSIZE:
         if (rb->mbuf->datalen != sizeof(struct winsize))
             break;
         /* The caller must ensure that the hvc is locked, which
          * is the case when called from hvc_iucv_get_chars() */
         __hvc_resize(priv->hvc, *((struct winsize *) rb->mbuf->data));
         break;
 
     case MSG_TYPE_ERROR:    /* ignored ... */
     case MSG_TYPE_TERMENV:  /* ignored ... */
     case MSG_TYPE_TERMIOS:  /* ignored ... */
         break;
     }
 
 out_remove_buffer:
     list_del(&rb->list);
     destroy_tty_buffer(rb);
     *has_more_data = !list_empty(&priv->tty_inqueue);
 
 out_written:
     return written;
 }
 
 /**
  * hvc_iucv_get_chars() - HVC get_chars operation.
  * @vtermno:    HVC virtual terminal number.
  * @buf:    Pointer to a buffer to store data
  * @count:  Size of buffer available for writing
  *
  * The HVC thread calls this method to read characters from the back-end.
  * If an IUCV communication path has been established, pending IUCV messages
  * are received and data is copied into buffer @buf up to @count bytes.
  *
  * Locking: The routine gets called under an irqsave() spinlock; and
  *      the routine locks the struct hvc_iucv_private->lock to call
  *      helper functions.
  */
 static int hvc_iucv_get_chars(uint32_t vtermno, char *buf, int count)
 {
     struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno);
     int written;
     int has_more_data;
 
     if (count <= 0)
         return 0;
 
     if (!priv)
         return -ENODEV;
 
     spin_lock(&priv->lock);
     has_more_data = 0;
     written = hvc_iucv_write(priv, buf, count, &has_more_data);
     spin_unlock(&priv->lock);
 
     /* if there are still messages on the queue... schedule another run */
     if (has_more_data)
         hvc_kick();
 
     return written;
 }
 
 /**
  * hvc_iucv_queue() - Buffer terminal data for sending.
  * @priv:   Pointer to struct hvc_iucv_private instance.
  * @buf:    Buffer containing data to send.
  * @count:  Size of buffer and amount of data to send.
  *
  * The function queues data for sending. To actually send the buffered data,
  * a work queue function is scheduled (with QUEUE_SNDBUF_DELAY).
  * The function returns the number of data bytes that has been buffered.
  *
  * If the device is not connected, data is ignored and the function returns
  * @count.
  * If the buffer is full, the function returns 0.
  * If an existing IUCV communicaton path has been severed, -EPIPE is returned
  * (that can be passed to HVC layer to cause a tty hangup).
  */
 static int hvc_iucv_queue(struct hvc_iucv_private *priv, const char *buf,
               int count)
 {
     size_t len;
 
     if (priv->iucv_state == IUCV_DISCONN)
         return count;           /* ignore data */
 
     if (priv->iucv_state == IUCV_SEVERED)
         return -EPIPE;
 
     len = min_t(size_t, count, SNDBUF_SIZE - priv->sndbuf_len);
     if (!len)
         return 0;
 
     memcpy(priv->sndbuf + priv->sndbuf_len, buf, len);
     priv->sndbuf_len += len;
 
     if (priv->iucv_state == IUCV_CONNECTED)
         schedule_delayed_work(&priv->sndbuf_work, QUEUE_SNDBUF_DELAY);
 
     return len;
 }
 
 /**
  * hvc_iucv_send() - Send an IUCV message containing terminal data.
  * @priv:   Pointer to struct hvc_iucv_private instance.
  *
  * If an IUCV communication path has been established, the buffered output data
  * is sent via an IUCV message and the number of bytes sent is returned.
  * Returns 0 if there is no established IUCV communication path or
  * -EPIPE if an existing IUCV communicaton path has been severed.
  */
 static int hvc_iucv_send(struct hvc_iucv_private *priv)
 {
     struct iucv_tty_buffer *sb;
     int rc, len;
 
     if (priv->iucv_state == IUCV_SEVERED)
         return -EPIPE;
 
     if (priv->iucv_state == IUCV_DISCONN)
         return -EIO;
 
     if (!priv->sndbuf_len)
         return 0;
 
     /* allocate internal buffer to store msg data and also compute total
      * message length */
     sb = alloc_tty_buffer(priv->sndbuf_len, GFP_ATOMIC);
     if (!sb)
         return -ENOMEM;
 
     memcpy(sb->mbuf->data, priv->sndbuf, priv->sndbuf_len);
     sb->mbuf->datalen = (u16) priv->sndbuf_len;
     sb->msg.length = MSG_SIZE(sb->mbuf->datalen);
 
     list_add_tail(&sb->list, &priv->tty_outqueue);
 
     rc = __iucv_message_send(priv->path, &sb->msg, 0, 0,
                  (void *) sb->mbuf, sb->msg.length);
     if (rc) {
         /* drop the message here; however we might want to handle
          * 0x03 (msg limit reached) by trying again... */
         list_del(&sb->list);
         destroy_tty_buffer(sb);
     }
     len = priv->sndbuf_len;
     priv->sndbuf_len = 0;
 
     return len;
 }
 
 /**
  * hvc_iucv_sndbuf_work() - Send buffered data over IUCV
  * @work:   Work structure.
  *
  * This work queue function sends buffered output data over IUCV and,
  * if not all buffered data could be sent, reschedules itself.
  */
 static void hvc_iucv_sndbuf_work(struct work_struct *work)
 {
     struct hvc_iucv_private *priv;
 
     priv = container_of(work, struct hvc_iucv_private, sndbuf_work.work);
 
     spin_lock_bh(&priv->lock);
     hvc_iucv_send(priv);
     spin_unlock_bh(&priv->lock);
 }
 
 /**
  * hvc_iucv_put_chars() - HVC put_chars operation.
  * @vtermno:    HVC virtual terminal number.
  * @buf:    Pointer to an buffer to read data from
  * @count:  Size of buffer available for reading
  *
  * The HVC thread calls this method to write characters to the back-end.
  * The function calls hvc_iucv_queue() to queue terminal data for sending.
  *
  * Locking: The method gets called under an irqsave() spinlock; and
  *      locks struct hvc_iucv_private->lock.
  */
 static int hvc_iucv_put_chars(uint32_t vtermno, const char *buf, int count)
 {
     struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno);
     int queued;
 
     if (count <= 0)
         return 0;
 
     if (!priv)
         return -ENODEV;
 
     spin_lock(&priv->lock);
     queued = hvc_iucv_queue(priv, buf, count);
     spin_unlock(&priv->lock);
 
     return queued;
 }
 
 /**
  * hvc_iucv_notifier_add() - HVC notifier for opening a TTY for the first time.
  * @hp: Pointer to the HVC device (struct hvc_struct)
  * @id: Additional data (originally passed to hvc_alloc): the index of an struct
  *  hvc_iucv_private instance.
  *
  * The function sets the tty state to TTY_OPENED for the struct hvc_iucv_private
  * instance that is derived from @id. Always returns 0.
  *
  * Locking: struct hvc_iucv_private->lock, spin_lock_bh
  */
 static int hvc_iucv_notifier_add(struct hvc_struct *hp, int id)
 {
     struct hvc_iucv_private *priv;
 
     priv = hvc_iucv_get_private(id);
     if (!priv)
         return 0;
 
     spin_lock_bh(&priv->lock);
     priv->tty_state = TTY_OPENED;
     spin_unlock_bh(&priv->lock);
 
     return 0;
 }
 
 /**
  * hvc_iucv_cleanup() - Clean up and reset a z/VM IUCV HVC instance.
  * @priv:   Pointer to the struct hvc_iucv_private instance.
  */
 static void hvc_iucv_cleanup(struct hvc_iucv_private *priv)
 {
     destroy_tty_buffer_list(&priv->tty_outqueue);
     destroy_tty_buffer_list(&priv->tty_inqueue);
 
     priv->tty_state = TTY_CLOSED;
     priv->iucv_state = IUCV_DISCONN;
 
     priv->sndbuf_len = 0;
 }
 
 /**
  * tty_outqueue_empty() - Test if the tty outq is empty
  * @priv:   Pointer to struct hvc_iucv_private instance.
  */
 static inline int tty_outqueue_empty(struct hvc_iucv_private *priv)
 {
     int rc;
 
     spin_lock_bh(&priv->lock);
     rc = list_empty(&priv->tty_outqueue);
     spin_unlock_bh(&priv->lock);
 
     return rc;
 }
 
 /**
  * flush_sndbuf_sync() - Flush send buffer and wait for completion
  * @priv:   Pointer to struct hvc_iucv_private instance.
  *
  * The routine cancels a pending sndbuf work, calls hvc_iucv_send()
  * to flush any buffered terminal output data and waits for completion.
  */
 static void flush_sndbuf_sync(struct hvc_iucv_private *priv)
 {
     int sync_wait;
 
     cancel_delayed_work_sync(&priv->sndbuf_work);
 
     spin_lock_bh(&priv->lock);
     hvc_iucv_send(priv);        /* force sending buffered data */
     sync_wait = !list_empty(&priv->tty_outqueue); /* anything queued ? */
     spin_unlock_bh(&priv->lock);
 
     if (sync_wait)
         wait_event_timeout(priv->sndbuf_waitq,
                    tty_outqueue_empty(priv), HZ/10);
 }
 
 /**
  * hvc_iucv_hangup() - Sever IUCV path and schedule hvc tty hang up
  * @priv:   Pointer to hvc_iucv_private structure
  *
  * This routine severs an existing IUCV communication path and hangs
  * up the underlying HVC terminal device.
  * The hang-up occurs only if an IUCV communication path is established;
  * otherwise there is no need to hang up the terminal device.
  *
  * The IUCV HVC hang-up is separated into two steps:
  * 1. After the IUCV path has been severed, the iucv_state is set to
  *    IUCV_SEVERED.
  * 2. Later, when the HVC thread calls hvc_iucv_get_chars(), the
  *    IUCV_SEVERED state causes the tty hang-up in the HVC layer.
  *
  * If the tty has not yet been opened, clean up the hvc_iucv_private
  * structure to allow re-connects.
  * If the tty has been opened, let get_chars() return -EPIPE to signal
  * the HVC layer to hang up the tty and, if so, wake up the HVC thread
  * to call get_chars()...
  *
  * Special notes on hanging up a HVC terminal instantiated as console:
  * Hang-up: 1. do_tty_hangup() replaces file ops (= hung_up_tty_fops)
  *      2. do_tty_hangup() calls tty->ops->close() for console_filp
  *          => no hangup notifier is called by HVC (default)
  *      2. hvc_close() returns because of tty_hung_up_p(filp)
  *          => no delete notifier is called!
  * Finally, the back-end is not being notified, thus, the tty session is
  * kept active (TTY_OPEN) to be ready for re-connects.
  *
  * Locking: spin_lock(&priv->lock) w/o disabling bh
  */
 static void hvc_iucv_hangup(struct hvc_iucv_private *priv)
 {
     struct iucv_path *path;
 
     path = NULL;
     spin_lock(&priv->lock);
     if (priv->iucv_state == IUCV_CONNECTED) {
         path = priv->path;
         priv->path = NULL;
         priv->iucv_state = IUCV_SEVERED;
         if (priv->tty_state == TTY_CLOSED)
             hvc_iucv_cleanup(priv);
         else
             /* console is special (see above) */
             if (priv->is_console) {
                 hvc_iucv_cleanup(priv);
                 priv->tty_state = TTY_OPENED;
             } else
                 hvc_kick();
     }
     spin_unlock(&priv->lock);
 
     /* finally sever path (outside of priv->lock due to lock ordering) */
     if (path) {
         iucv_path_sever(path, NULL);
         iucv_path_free(path);
     }
 }
 
 /**
  * hvc_iucv_notifier_hangup() - HVC notifier for TTY hangups.
  * @hp:     Pointer to the HVC device (struct hvc_struct)
  * @id:     Additional data (originally passed to hvc_alloc):
  *      the index of an struct hvc_iucv_private instance.
  *
  * This routine notifies the HVC back-end that a tty hangup (carrier loss,
  * virtual or otherwise) has occurred.
  * The z/VM IUCV HVC device driver ignores virtual hangups (vhangup())
  * to keep an existing IUCV communication path established.
  * (Background: vhangup() is called from user space (by getty or login) to
  *      disable writing to the tty by other applications).
  * If the tty has been opened and an established IUCV path has been severed
  * (we caused the tty hangup), the function calls hvc_iucv_cleanup().
  *
  * Locking: struct hvc_iucv_private->lock
  */
 static void hvc_iucv_notifier_hangup(struct hvc_struct *hp, int id)
 {
     struct hvc_iucv_private *priv;
 
     priv = hvc_iucv_get_private(id);
     if (!priv)
         return;
 
     flush_sndbuf_sync(priv);
 
     spin_lock_bh(&priv->lock);
     /* NOTE: If the hangup was scheduled by ourself (from the iucv
      *   path_servered callback [IUCV_SEVERED]), we have to clean up
      *   our structure and to set state to TTY_CLOSED.
      *   If the tty was hung up otherwise (e.g. vhangup()), then we
      *   ignore this hangup and keep an established IUCV path open...
      *   (...the reason is that we are not able to connect back to the
      *   client if we disconnect on hang up) */
     priv->tty_state = TTY_CLOSED;
 
     if (priv->iucv_state == IUCV_SEVERED)
         hvc_iucv_cleanup(priv);
     spin_unlock_bh(&priv->lock);
 }
 
 /**
  * hvc_iucv_dtr_rts() - HVC notifier for handling DTR/RTS
  * @hp:     Pointer the HVC device (struct hvc_struct)
  * @raise:  Non-zero to raise or zero to lower DTR/RTS lines
  *
  * This routine notifies the HVC back-end to raise or lower DTR/RTS
  * lines.  Raising DTR/RTS is ignored.  Lowering DTR/RTS indicates to
  * drop the IUCV connection (similar to hang up the modem).
  */
 static void hvc_iucv_dtr_rts(struct hvc_struct *hp, int raise)
 {
     struct hvc_iucv_private *priv;
     struct iucv_path        *path;
 
     /* Raising the DTR/RTS is ignored as IUCV connections can be
      * established at any times.
      */
     if (raise)
         return;
 
     priv = hvc_iucv_get_private(hp->vtermno);
     if (!priv)
         return;
 
     /* Lowering the DTR/RTS lines disconnects an established IUCV
      * connection.
      */
     flush_sndbuf_sync(priv);
 
     spin_lock_bh(&priv->lock);
     path = priv->path;      /* save reference to IUCV path */
     priv->path = NULL;
     priv->iucv_state = IUCV_DISCONN;
     spin_unlock_bh(&priv->lock);
 
     /* Sever IUCV path outside of priv->lock due to lock ordering of:
      * priv->lock <--> iucv_table_lock */
     if (path) {
         iucv_path_sever(path, NULL);
         iucv_path_free(path);
     }
 }
 
 /**
  * hvc_iucv_notifier_del() - HVC notifier for closing a TTY for the last time.
  * @hp:     Pointer to the HVC device (struct hvc_struct)
  * @id:     Additional data (originally passed to hvc_alloc):
  *      the index of an struct hvc_iucv_private instance.
  *
  * This routine notifies the HVC back-end that the last tty device fd has been
  * closed.  The function cleans up tty resources.  The clean-up of the IUCV
  * connection is done in hvc_iucv_dtr_rts() and depends on the HUPCL termios
  * control setting.
  *
  * Locking: struct hvc_iucv_private->lock
  */
 static void hvc_iucv_notifier_del(struct hvc_struct *hp, int id)
 {
     struct hvc_iucv_private *priv;
 
     priv = hvc_iucv_get_private(id);
     if (!priv)
         return;
 
     flush_sndbuf_sync(priv);
 
     spin_lock_bh(&priv->lock);
     destroy_tty_buffer_list(&priv->tty_outqueue);
     destroy_tty_buffer_list(&priv->tty_inqueue);
     priv->tty_state = TTY_CLOSED;
     priv->sndbuf_len = 0;
     spin_unlock_bh(&priv->lock);
 }
 
 /**
  * hvc_iucv_filter_connreq() - Filter connection request based on z/VM user ID
  * @ipvmid: Originating z/VM user ID (right padded with blanks)
  *
  * Returns 0 if the z/VM user ID that is specified with @ipvmid is permitted to
  * connect, otherwise non-zero.
  */
 static int hvc_iucv_filter_connreq(u8 ipvmid[8])
 {
     const char *wildcard, *filter_entry;
     size_t i, len;
 
     /* Note: default policy is ACCEPT if no filter is set */
     if (!hvc_iucv_filter_size)
         return 0;
 
     for (i = 0; i < hvc_iucv_filter_size; i++) {
         filter_entry = hvc_iucv_filter + (8 * i);
 
         /* If a filter entry contains the filter wildcard character,
          * reduce the length to match the leading portion of the user
          * ID only (wildcard match).  Characters following the wildcard
          * are ignored.
          */
         wildcard = strnchr(filter_entry, 8, FILTER_WILDCARD_CHAR);
         len = (wildcard) ? wildcard - filter_entry : 8;
         if (0 == memcmp(ipvmid, filter_entry, len))
             return 0;
     }
     return 1;
 }
 
 /**
  * hvc_iucv_path_pending() - IUCV handler to process a connection request.
  * @path:   Pending path (struct iucv_path)
  * @ipvmid: z/VM system identifier of originator
  * @ipuser: User specified data for this path
  *      (AF_IUCV: port/service name and originator port)
  *
  * The function uses the @ipuser data to determine if the pending path belongs
  * to a terminal managed by this device driver.
  * If the path belongs to this driver, ensure that the terminal is not accessed
  * multiple times (only one connection to a terminal is allowed).
  * If the terminal is not yet connected, the pending path is accepted and is
  * associated to the appropriate struct hvc_iucv_private instance.
  *
  * Returns 0 if @path belongs to a terminal managed by the this device driver;
  * otherwise returns -ENODEV in order to dispatch this path to other handlers.
  *
  * Locking: struct hvc_iucv_private->lock
  */
 static  int hvc_iucv_path_pending(struct iucv_path *path, u8 *ipvmid,
                   u8 *ipuser)
 {
     struct hvc_iucv_private *priv, *tmp;
     u8 wildcard[9] = "lnxhvc  ";
     int i, rc, find_unused;
     u8 nuser_data[16];
     u8 vm_user_id[9];
 
     ASCEBC(wildcard, sizeof(wildcard));
     find_unused = !memcmp(wildcard, ipuser, 8);
 
     /* First, check if the pending path request is managed by this
      * IUCV handler:
      * - find a disconnected device if ipuser contains the wildcard
      * - find the device that matches the terminal ID in ipuser
      */
     priv = NULL;
     for (i = 0; i < hvc_iucv_devices; i++) {
         tmp = hvc_iucv_table[i];
         if (!tmp)
             continue;
 
         if (find_unused) {
             spin_lock(&tmp->lock);
             if (tmp->iucv_state == IUCV_DISCONN)
                 priv = tmp;
             spin_unlock(&tmp->lock);
 
         } else if (!memcmp(tmp->srv_name, ipuser, 8))
                 priv = tmp;
         if (priv)
             break;
     }
     if (!priv)
         return -ENODEV;
 
     /* Enforce that ipvmid is allowed to connect to us */
     read_lock(&hvc_iucv_filter_lock);
     rc = hvc_iucv_filter_connreq(ipvmid);
     read_unlock(&hvc_iucv_filter_lock);
     if (rc) {
         iucv_path_sever(path, ipuser);
         iucv_path_free(path);
         memcpy(vm_user_id, ipvmid, 8);
         vm_user_id[8] = 0;
         pr_info("A connection request from z/VM user ID %s "
             "was refused\n", vm_user_id);
         return 0;
     }
 
     spin_lock(&priv->lock);
 
     /* If the terminal is already connected or being severed, then sever
      * this path to enforce that there is only ONE established communication
      * path per terminal. */
     if (priv->iucv_state != IUCV_DISCONN) {
         iucv_path_sever(path, ipuser);
         iucv_path_free(path);
         goto out_path_handled;
     }
 
     /* accept path */
     memcpy(nuser_data, ipuser + 8, 8);  /* remote service (for af_iucv) */
     memcpy(nuser_data + 8, ipuser, 8);  /* local service  (for af_iucv) */
     path->msglim = 0xffff;          /* IUCV MSGLIMIT */
     path->flags &= ~IUCV_IPRMDATA;      /* TODO: use IUCV_IPRMDATA */
     rc = iucv_path_accept(path, &hvc_iucv_handler, nuser_data, priv);
     if (rc) {
         iucv_path_sever(path, ipuser);
         iucv_path_free(path);
         goto out_path_handled;
     }
     priv->path = path;
     priv->iucv_state = IUCV_CONNECTED;
 
     /* store path information */
     memcpy(priv->info_path, ipvmid, 8);
     memcpy(priv->info_path + 8, ipuser + 8, 8);
 
     /* flush buffered output data... */
     schedule_delayed_work(&priv->sndbuf_work, 5);
 
 out_path_handled:
     spin_unlock(&priv->lock);
     return 0;
 }
 
 /**
  * hvc_iucv_path_severed() - IUCV handler to process a path sever.
  * @path:   Pending path (struct iucv_path)
  * @ipuser: User specified data for this path
  *      (AF_IUCV: port/service name and originator port)
  *
  * This function calls the hvc_iucv_hangup() function for the
  * respective IUCV HVC terminal.
  *
  * Locking: struct hvc_iucv_private->lock
  */
 static void hvc_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
 {
     struct hvc_iucv_private *priv = path->private;
 
     hvc_iucv_hangup(priv);
 }
 
 /**
  * hvc_iucv_msg_pending() - IUCV handler to process an incoming IUCV message.
  * @path:   Pending path (struct iucv_path)
  * @msg:    Pointer to the IUCV message
  *
  * The function puts an incoming message on the input queue for later
  * processing (by hvc_iucv_get_chars() / hvc_iucv_write()).
  * If the tty has not yet been opened, the message is rejected.
  *
  * Locking: struct hvc_iucv_private->lock
  */
 static void hvc_iucv_msg_pending(struct iucv_path *path,
                  struct iucv_message *msg)
 {
     struct hvc_iucv_private *priv = path->private;
     struct iucv_tty_buffer *rb;
 
     /* reject messages that exceed max size of iucv_tty_msg->datalen */
     if (msg->length > MSG_SIZE(MSG_MAX_DATALEN)) {
         iucv_message_reject(path, msg);
         return;
     }
 
     spin_lock(&priv->lock);
 
     /* reject messages if tty has not yet been opened */
     if (priv->tty_state == TTY_CLOSED) {
         iucv_message_reject(path, msg);
         goto unlock_return;
     }
 
     /* allocate tty buffer to save iucv msg only */
     rb = alloc_tty_buffer(0, GFP_ATOMIC);
     if (!rb) {
         iucv_message_reject(path, msg);
         goto unlock_return; /* -ENOMEM */
     }
     rb->msg = *msg;
 
     list_add_tail(&rb->list, &priv->tty_inqueue);
 
     hvc_kick(); /* wake up hvc thread */
 
 unlock_return:
     spin_unlock(&priv->lock);
 }
 
 /**
  * hvc_iucv_msg_complete() - IUCV handler to process message completion
  * @path:   Pending path (struct iucv_path)
  * @msg:    Pointer to the IUCV message
  *
  * The function is called upon completion of message delivery to remove the
  * message from the outqueue. Additional delivery information can be found
  * msg->audit: rejected messages (0x040000 (IPADRJCT)), and
  *         purged messages   (0x010000 (IPADPGNR)).
  *
  * Locking: struct hvc_iucv_private->lock
  */
 static void hvc_iucv_msg_complete(struct iucv_path *path,
                   struct iucv_message *msg)
 {
     struct hvc_iucv_private *priv = path->private;
     struct iucv_tty_buffer  *ent, *next;
     LIST_HEAD(list_remove);
 
     spin_lock(&priv->lock);
     list_for_each_entry_safe(ent, next, &priv->tty_outqueue, list)
         if (ent->msg.id == msg->id) {
             list_move(&ent->list, &list_remove);
             break;
         }
     wake_up(&priv->sndbuf_waitq);
     spin_unlock(&priv->lock);
     destroy_tty_buffer_list(&list_remove);
 }
 
 static ssize_t hvc_iucv_dev_termid_show(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
 {
     struct hvc_iucv_private *priv = dev_get_drvdata(dev);
     size_t len;
 
     len = sizeof(priv->srv_name);
     memcpy(buf, priv->srv_name, len);
     EBCASC(buf, len);
     buf[len++] = '\n';
     return len;
 }
 
 static ssize_t hvc_iucv_dev_state_show(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
 {
     struct hvc_iucv_private *priv = dev_get_drvdata(dev);
     return sprintf(buf, "%u:%u\n", priv->iucv_state, priv->tty_state);
 }
 
 static ssize_t hvc_iucv_dev_peer_show(struct device *dev,
                       struct device_attribute *attr,
                       char *buf)
 {
     struct hvc_iucv_private *priv = dev_get_drvdata(dev);
     char vmid[9], ipuser[9];
 
     memset(vmid, 0, sizeof(vmid));
     memset(ipuser, 0, sizeof(ipuser));
 
     spin_lock_bh(&priv->lock);
     if (priv->iucv_state == IUCV_CONNECTED) {
         memcpy(vmid, priv->info_path, 8);
         memcpy(ipuser, priv->info_path + 8, 8);
     }
     spin_unlock_bh(&priv->lock);
     EBCASC(ipuser, 8);
 
     return sprintf(buf, "%s:%s\n", vmid, ipuser);
 }
 
 
 /* HVC operations */
 static const struct hv_ops hvc_iucv_ops = {
     .get_chars = hvc_iucv_get_chars,
     .put_chars = hvc_iucv_put_chars,
     .notifier_add = hvc_iucv_notifier_add,
     .notifier_del = hvc_iucv_notifier_del,
     .notifier_hangup = hvc_iucv_notifier_hangup,
     .dtr_rts = hvc_iucv_dtr_rts,
 };
 
 /* IUCV HVC device attributes */
 static DEVICE_ATTR(termid, 0640, hvc_iucv_dev_termid_show, NULL);
 static DEVICE_ATTR(state, 0640, hvc_iucv_dev_state_show, NULL);
 static DEVICE_ATTR(peer, 0640, hvc_iucv_dev_peer_show, NULL);
 static struct attribute *hvc_iucv_dev_attrs[] = {
     &dev_attr_termid.attr,
     &dev_attr_state.attr,
     &dev_attr_peer.attr,
     NULL,
 };
 static struct attribute_group hvc_iucv_dev_attr_group = {
     .attrs = hvc_iucv_dev_attrs,
 };
 static const struct attribute_group *hvc_iucv_dev_attr_groups[] = {
     &hvc_iucv_dev_attr_group,
     NULL,
 };
 
 
 /**
  * hvc_iucv_alloc() - Allocates a new struct hvc_iucv_private instance
  * @id:         hvc_iucv_table index
  * @is_console:     Flag if the instance is used as Linux console
  *
  * This function allocates a new hvc_iucv_private structure and stores
  * the instance in hvc_iucv_table at index @id.
  * Returns 0 on success; otherwise non-zero.
  */
 static int __init hvc_iucv_alloc(int id, unsigned int is_console)
 {
     struct hvc_iucv_private *priv;
     char name[9];
     int rc;
 
     priv = kzalloc(sizeof(struct hvc_iucv_private), GFP_KERNEL);
     if (!priv)
         return -ENOMEM;
 
     spin_lock_init(&priv->lock);
     INIT_LIST_HEAD(&priv->tty_outqueue);
     INIT_LIST_HEAD(&priv->tty_inqueue);
     INIT_DELAYED_WORK(&priv->sndbuf_work, hvc_iucv_sndbuf_work);
     init_waitqueue_head(&priv->sndbuf_waitq);
 
     priv->sndbuf = (void *) get_zeroed_page(GFP_KERNEL);
     if (!priv->sndbuf) {
         kfree(priv);
         return -ENOMEM;
     }
 
     /* set console flag */
     priv->is_console = is_console;
 
     /* allocate hvc device */
     priv->hvc = hvc_alloc(HVC_IUCV_MAGIC + id, /*         PAGE_SIZE */
                   HVC_IUCV_MAGIC + id, &hvc_iucv_ops, 256);
     if (IS_ERR(priv->hvc)) {
         rc = PTR_ERR(priv->hvc);
         goto out_error_hvc;
     }
 
     /* notify HVC thread instead of using polling */
     priv->hvc->irq_requested = 1;
 
     /* setup iucv related information */
     snprintf(name, 9, "lnxhvc%-2d", id);
     memcpy(priv->srv_name, name, 8);
     ASCEBC(priv->srv_name, 8);
 
     /* create and setup device */
     priv->dev = kzalloc(sizeof(*priv->dev), GFP_KERNEL);
     if (!priv->dev) {
         rc = -ENOMEM;
         goto out_error_dev;
     }
     dev_set_name(priv->dev, "hvc_iucv%d", id);
     dev_set_drvdata(priv->dev, priv);
     priv->dev->bus = &iucv_bus;
     priv->dev->parent = iucv_root;
     priv->dev->groups = hvc_iucv_dev_attr_groups;
     priv->dev->release = (void (*)(struct device *)) kfree;
     rc = device_register(priv->dev);
     if (rc) {
         put_device(priv->dev);
         goto out_error_dev;
     }
 
     hvc_iucv_table[id] = priv;
     return 0;
 
 out_error_dev:
     hvc_remove(priv->hvc);
 out_error_hvc:
     free_page((unsigned long) priv->sndbuf);
     kfree(priv);
 
     return rc;
 }
 
 /**
  * hvc_iucv_destroy() - Destroy and free hvc_iucv_private instances
  */
 static void __init hvc_iucv_destroy(struct hvc_iucv_private *priv)
 {
     hvc_remove(priv->hvc);
     device_unregister(priv->dev);
     free_page((unsigned long) priv->sndbuf);
     kfree(priv);
 }
 
 /**
  * hvc_iucv_parse_filter() - Parse filter for a single z/VM user ID
  * @filter: String containing a comma-separated list of z/VM user IDs
  * @dest:   Location where to store the parsed z/VM user ID
  */
 static const char *hvc_iucv_parse_filter(const char *filter, char *dest)
 {
     const char *nextdelim, *residual;
     size_t len;
 
     nextdelim = strchr(filter, ',');
     if (nextdelim) {
         len = nextdelim - filter;
         residual = nextdelim + 1;
     } else {
         len = strlen(filter);
         residual = filter + len;
     }
 
     if (len == 0)
         return ERR_PTR(-EINVAL);
 
     /* check for '\n' (if called from sysfs) */
     if (filter[len - 1] == '\n')
         len--;
 
     /* prohibit filter entries containing the wildcard character only */
     if (len == 1 && *filter == FILTER_WILDCARD_CHAR)
         return ERR_PTR(-EINVAL);
 
     if (len > 8)
         return ERR_PTR(-EINVAL);
 
     /* pad with blanks and save upper case version of user ID */
     memset(dest, ' ', 8);
     while (len--)
         dest[len] = toupper(filter[len]);
     return residual;
 }
 
 /**
  * hvc_iucv_setup_filter() - Set up z/VM user ID filter
  * @filter: String consisting of a comma-separated list of z/VM user IDs
  *
  * The function parses the @filter string and creates an array containing
  * the list of z/VM user ID filter entries.
  * Return code 0 means success, -EINVAL if the filter is syntactically
  * incorrect, -ENOMEM if there was not enough memory to allocate the
  * filter list array, or -ENOSPC if too many z/VM user IDs have been specified.
  */
 static int hvc_iucv_setup_filter(const char *val)
 {
     const char *residual;
     int err;
     size_t size, count;
     void *array, *old_filter;
 
     count = strlen(val);
     if (count == 0 || (count == 1 && val[0] == '\n')) {
         size  = 0;
         array = NULL;
         goto out_replace_filter;    /* clear filter */
     }
 
     /* count user IDs in order to allocate sufficient memory */
     size = 1;
     residual = val;
     while ((residual = strchr(residual, ',')) != NULL) {
         residual++;
         size++;
     }
 
     /* check if the specified list exceeds the filter limit */
     if (size > MAX_VMID_FILTER)
         return -ENOSPC;
 
     array = kcalloc(size, 8, GFP_KERNEL);
     if (!array)
         return -ENOMEM;
 
     count = size;
     residual = val;
     while (*residual && count) {
         residual = hvc_iucv_parse_filter(residual,
                          array + ((size - count) * 8));
         if (IS_ERR(residual)) {
             err = PTR_ERR(residual);
             kfree(array);
             goto out_err;
         }
         count--;
     }
 
 out_replace_filter:
     write_lock_bh(&hvc_iucv_filter_lock);
     old_filter = hvc_iucv_filter;
     hvc_iucv_filter_size = size;
     hvc_iucv_filter = array;
     write_unlock_bh(&hvc_iucv_filter_lock);
     kfree(old_filter);
 
     err = 0;
 out_err:
     return err;
 }
 
 /**
  * param_set_vmidfilter() - Set z/VM user ID filter parameter
  * @val:    String consisting of a comma-separated list of z/VM user IDs
  * @kp:     Kernel parameter pointing to hvc_iucv_filter array
  *
  * The function sets up the z/VM user ID filter specified as comma-separated
  * list of user IDs in @val.
  * Note: If it is called early in the boot process, @val is stored and
  *   parsed later in hvc_iucv_init().
  */
 static int param_set_vmidfilter(const char *val, const struct kernel_param *kp)
 {
     int rc;
 
     if (!MACHINE_IS_VM || !hvc_iucv_devices)
         return -ENODEV;
 
     if (!val)
         return -EINVAL;
 
     rc = 0;
     if (slab_is_available())
         rc = hvc_iucv_setup_filter(val);
     else
         hvc_iucv_filter_string = val;   /* defer... */
     return rc;
 }
 
 /**
  * param_get_vmidfilter() - Get z/VM user ID filter
  * @buffer: Buffer to store z/VM user ID filter,
  *      (buffer size assumption PAGE_SIZE)
  * @kp:     Kernel parameter pointing to the hvc_iucv_filter array
  *
  * The function stores the filter as a comma-separated list of z/VM user IDs
  * in @buffer. Typically, sysfs routines call this function for attr show.
  */
 static int param_get_vmidfilter(char *buffer, const struct kernel_param *kp)
 {
     int rc;
     size_t index, len;
     void *start, *end;
 
     if (!MACHINE_IS_VM || !hvc_iucv_devices)
         return -ENODEV;
 
     rc = 0;
     read_lock_bh(&hvc_iucv_filter_lock);
     for (index = 0; index < hvc_iucv_filter_size; index++) {
         start = hvc_iucv_filter + (8 * index);
         end   = memchr(start, ' ', 8);
         len   = (end) ? end - start : 8;
         memcpy(buffer + rc, start, len);
         rc += len;
         buffer[rc++] = ',';
     }
     read_unlock_bh(&hvc_iucv_filter_lock);
     if (rc)
         buffer[--rc] = '\0';    /* replace last comma and update rc */
     return rc;
 }
 
 #define param_check_vmidfilter(name, p) __param_check(name, p, void)
 
 static const struct kernel_param_ops param_ops_vmidfilter = {
     .set = param_set_vmidfilter,
     .get = param_get_vmidfilter,
 };
 
 /**
  * hvc_iucv_init() - z/VM IUCV HVC device driver initialization
  */
 static int __init hvc_iucv_init(void)
 {
     int rc;
     unsigned int i;
 
     if (!hvc_iucv_devices)
         return -ENODEV;
 
     if (!MACHINE_IS_VM) {
         pr_notice("The z/VM IUCV HVC device driver cannot "
                "be used without z/VM\n");
         rc = -ENODEV;
         goto out_error;
     }
 
     if (hvc_iucv_devices > MAX_HVC_IUCV_LINES) {
         pr_err("%lu is not a valid value for the hvc_iucv= "
             "kernel parameter\n", hvc_iucv_devices);
         rc = -EINVAL;
         goto out_error;
     }
 
     /* parse hvc_iucv_allow string and create z/VM user ID filter list */
     if (hvc_iucv_filter_string) {
         rc = hvc_iucv_setup_filter(hvc_iucv_filter_string);
         switch (rc) {
         case 0:
             break;
         case -ENOMEM:
             pr_err("Allocating memory failed with "
                 "reason code=%d\n", 3);
             goto out_error;
         case -EINVAL:
             pr_err("hvc_iucv_allow= does not specify a valid "
                 "z/VM user ID list\n");
             goto out_error;
         case -ENOSPC:
             pr_err("hvc_iucv_allow= specifies too many "
                 "z/VM user IDs\n");
             goto out_error;
         default:
             goto out_error;
         }
     }
 
     hvc_iucv_buffer_cache = kmem_cache_create(KMSG_COMPONENT,
                        sizeof(struct iucv_tty_buffer),
                        0, 0, NULL);
     if (!hvc_iucv_buffer_cache) {
         pr_err("Allocating memory failed with reason code=%d\n", 1);
         rc = -ENOMEM;
         goto out_error;
     }
 
     hvc_iucv_mempool = mempool_create_slab_pool(MEMPOOL_MIN_NR,
                             hvc_iucv_buffer_cache);
     if (!hvc_iucv_mempool) {
         pr_err("Allocating memory failed with reason code=%d\n", 2);
         kmem_cache_destroy(hvc_iucv_buffer_cache);
         rc = -ENOMEM;
         goto out_error;
     }
 
     /* register the first terminal device as console
      * (must be done before allocating hvc terminal devices) */
     rc = hvc_instantiate(HVC_IUCV_MAGIC, IUCV_HVC_CON_IDX, &hvc_iucv_ops);
     if (rc) {
         pr_err("Registering HVC terminal device as "
                "Linux console failed\n");
         goto out_error_memory;
     }
 
     /* allocate hvc_iucv_private structs */
     for (i = 0; i < hvc_iucv_devices; i++) {
         rc = hvc_iucv_alloc(i, (i == IUCV_HVC_CON_IDX) ? 1 : 0);
         if (rc) {
             pr_err("Creating a new HVC terminal device "
                 "failed with error code=%d\n", rc);
             goto out_error_hvc;
         }
     }
 
     /* register IUCV callback handler */
     rc = iucv_register(&hvc_iucv_handler, 0);
     if (rc) {
         pr_err("Registering IUCV handlers failed with error code=%d\n",
             rc);
         goto out_error_hvc;
     }
 
     return 0;
 
 out_error_hvc:
     for (i = 0; i < hvc_iucv_devices; i++)
         if (hvc_iucv_table[i])
             hvc_iucv_destroy(hvc_iucv_table[i]);
 out_error_memory:
     mempool_destroy(hvc_iucv_mempool);
     kmem_cache_destroy(hvc_iucv_buffer_cache);
 out_error:
     kfree(hvc_iucv_filter);
     hvc_iucv_devices = 0; /* ensure that we do not provide any device */
     return rc;
 }
 
 /**
  * hvc_iucv_config() - Parsing of hvc_iucv=  kernel command line parameter
  * @val:    Parameter value (numeric)
  */
 static  int __init hvc_iucv_config(char *val)
 {
     if (kstrtoul(val, 10, &hvc_iucv_devices))
         pr_warn("hvc_iucv= invalid parameter value '%s'\n", val);
     return 1;
 }
 
 
 device_initcall(hvc_iucv_init);
 __setup("hvc_iucv=", hvc_iucv_config);
 core_param(hvc_iucv_allow, hvc_iucv_filter, vmidfilter, 0640);

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