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Commit 17e19f04 authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Martin Schwidefsky
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[S390] hvc_iucv: Update function documentation 

Update documentation of functions.
Signed-off-by: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent c45ce4b5
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drivers/char/hvc_iucv.c
View file @ 17e19f04
/*
* hvc_iucv.c - z/VM IUCV back-end for the Hypervisor Console (HVC)
* hvc_iucv.c - z/VM IUCV hypervisor console (HVC) device driver
*
* This back-end for HVC provides terminal access via
* This HVC device driver provides terminal access using
* z/VM IUCV communication paths.
*
* Copyright IBM Corp. 2008.
* Copyright IBM Corp. 2008
*
* 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 <asm/ebcdic.h>
......@@ -22,7 +23,7 @@
#include "hvc_console.h"
/* HVC backend for z/VM IUCV */
/* 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)
......@@ -35,7 +36,6 @@
#define MSG_TYPE_WINSIZE 0x08 /* Terminal window size update */
#define MSG_TYPE_DATA 0x10 /* Terminal data */
#define MSG_SIZE(s) ((s) + offsetof(struct iucv_tty_msg, data))
struct iucv_tty_msg {
u8 version; /* Message version */
u8 type; /* Message type */
......@@ -43,6 +43,7 @@ struct iucv_tty_msg {
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,
......@@ -56,7 +57,7 @@ enum tty_state_t {
};
struct hvc_iucv_private {
struct hvc_struct *hvc; /* HVC console struct reference */
struct hvc_struct *hvc; /* HVC struct reference */
u8 srv_name[8]; /* IUCV service name (ebcdic) */
enum iucv_state_t iucv_state; /* IUCV connection status */
enum tty_state_t tty_state; /* TTY status */
......@@ -74,7 +75,7 @@ struct hvc_iucv_private {
struct iucv_tty_buffer {
struct list_head list; /* list pointer */
struct iucv_message msg; /* store an incoming IUCV message */
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 */
};
......@@ -120,7 +121,7 @@ struct hvc_iucv_private *hvc_iucv_get_private(uint32_t num)
}
/**
* alloc_tty_buffer() - Returns a new struct iucv_tty_buffer element.
* 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.
*
......@@ -128,7 +129,6 @@ struct hvc_iucv_private *hvc_iucv_get_private(uint32_t num)
* allocates an internal data buffer with the specified size @size.
* 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)
......@@ -157,9 +157,6 @@ static struct iucv_tty_buffer *alloc_tty_buffer(size_t size, gfp_t flags)
/**
* destroy_tty_buffer() - destroy struct iucv_tty_buffer element.
* @bufp: Pointer to a struct iucv_tty_buffer element, SHALL NOT be NULL.
*
* The destroy_tty_buffer() function frees the internal data buffer and returns
* the struct iucv_tty_buffer element back to the mempool for freeing.
*/
static void destroy_tty_buffer(struct iucv_tty_buffer *bufp)
{
......@@ -169,11 +166,7 @@ static void destroy_tty_buffer(struct iucv_tty_buffer *bufp)
/**
* destroy_tty_buffer_list() - call destroy_tty_buffer() for each list element.
* @list: List head pointer to a list containing struct iucv_tty_buffer
* elements.
*
* Calls destroy_tty_buffer() for each struct iucv_tty_buffer element in the
* list @list.
* @list: List containing struct iucv_tty_buffer elements.
*/
static void destroy_tty_buffer_list(struct list_head *list)
{
......@@ -186,24 +179,24 @@ static void destroy_tty_buffer_list(struct list_head *list)
}
/**
* hvc_iucv_write() - Receive IUCV message write data to HVC console buffer.
* @priv: Pointer to hvc_iucv_private structure.
* @buf: HVC console buffer for writing received terminal data.
* @count: HVC console buffer size.
* 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, then the
* 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 the message data has been entirely written, the message is removed from
* 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 console layer).
* 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)
......@@ -212,12 +205,12 @@ static int hvc_iucv_write(struct hvc_iucv_private *priv,
int written;
int rc;
/* Immediately return if there is no IUCV connection */
/* 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 console layer to hang up the tty device. */
/* 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;
......@@ -225,7 +218,7 @@ static int hvc_iucv_write(struct hvc_iucv_private *priv,
if (list_empty(&priv->tty_inqueue))
return 0;
/* receive a iucv message and flip data to the tty (ldisc) */
/* 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;
......@@ -268,7 +261,7 @@ static int hvc_iucv_write(struct hvc_iucv_private *priv,
case MSG_TYPE_WINSIZE:
if (rb->mbuf->datalen != sizeof(struct winsize))
break;
hvc_resize(priv->hvc, *((struct winsize *)rb->mbuf->data));
hvc_resize(priv->hvc, *((struct winsize *) rb->mbuf->data));
break;
case MSG_TYPE_ERROR: /* ignored ... */
......@@ -292,10 +285,9 @@ out_written:
* @buf: Pointer to a buffer to store data
* @count: Size of buffer available for writing
*
* The hvc_console thread calls this method to read characters from
* the terminal backend. If an IUCV communication path has been established,
* pending IUCV messages are received and data is copied into buffer @buf
* up to @count bytes.
* 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
......@@ -332,17 +324,17 @@ static int hvc_iucv_get_chars(uint32_t vtermno, char *buf, int count)
* @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).
* 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, the function returns
* -EPIPE (can be passed to HVC layer to cause a tty hangup).
* 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)
int count)
{
size_t len;
......@@ -369,12 +361,10 @@ static int hvc_iucv_queue(struct hvc_iucv_private *priv, const char *buf,
* 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 queued data
* for output are sent via an IUCV message.
*
* If there is no IUCV communication path established, the function returns 0.
* If an existing IUCV communicaton path has been severed, the function returns
* -EPIPE.
* 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)
{
......@@ -420,15 +410,14 @@ static int hvc_iucv_send(struct hvc_iucv_private *priv)
* hvc_iucv_sndbuf_work() - Send buffered data over IUCV
* @work: Work structure.
*
* The function sends buffered output data over IUCV and, if necessary,
* reschedules itself if not all buffered data could be sent.
* 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);
if (!priv)
return;
......@@ -443,10 +432,8 @@ static void hvc_iucv_sndbuf_work(struct work_struct *work)
* @buf: Pointer to an buffer to read data from
* @count: Size of buffer available for reading
*
* The hvc_console thread calls this method to write characters from
* to the terminal backend.
* The function calls hvc_iucv_send() under the lock of the
* struct hvc_iucv_private instance that corresponds to the tty @vtermno.
* 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.
......@@ -496,12 +483,8 @@ static int hvc_iucv_notifier_add(struct hvc_struct *hp, int id)
}
/**
* hvc_iucv_cleanup() - Clean up function if the tty portion is finally closed.
* hvc_iucv_cleanup() - Clean up and reset a z/VM IUCV HVC instance.
* @priv: Pointer to the struct hvc_iucv_private instance.
*
* The functions severs the established IUCV communication path (if any), and
* destroy struct iucv_tty_buffer elements from the in- and outqueue. Finally,
* the functions resets the states to TTY_CLOSED and IUCV_DISCONN.
*/
static void hvc_iucv_cleanup(struct hvc_iucv_private *priv)
{
......@@ -553,22 +536,19 @@ static void flush_sndbuf_sync(struct hvc_iucv_private *priv)
}
/**
* 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.
* 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 backend that a tty hangup (carrier loss,
* This routine notifies the HVC back-end that a tty hangup (carrier loss,
* virtual or otherwise) has occured.
*
* The HVC backend for z/VM IUCV ignores virtual hangups (vhangup()), to keep
* an existing IUCV communication path established.
* 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 (e.g. getty) and an established IUCV path has been
* severed (we caused the tty hangup in that case), then the functions invokes
* hvc_iucv_cleanup() to clean up.
* 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
*/
......@@ -584,10 +564,8 @@ static void hvc_iucv_notifier_hangup(struct hvc_struct *hp, int id)
spin_lock_bh(&priv->lock);
/* NOTE: If the hangup was scheduled by ourself (from the iucv
* path_servered callback [IUCV_SEVERED]), then we have to
* finally clean up the tty backend structure and set state to
* TTY_CLOSED.
*
* 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
......@@ -605,10 +583,9 @@ static void hvc_iucv_notifier_hangup(struct hvc_struct *hp, int id)
* @id: Additional data (originally passed to hvc_alloc):
* the index of an struct hvc_iucv_private instance.
*
* This routine notifies the HVC backend that the last tty device file
* descriptor has been closed.
* The function calls hvc_iucv_cleanup() to clean up the struct hvc_iucv_private
* instance.
* This routine notifies the HVC back-end that the last tty device fd has been
* closed. The function calls hvc_iucv_cleanup() to clean up the struct
* hvc_iucv_private instance.
*
* Locking: struct hvc_iucv_private->lock
*/
......@@ -640,20 +617,18 @@ static void hvc_iucv_notifier_del(struct hvc_struct *hp, int id)
/**
* hvc_iucv_path_pending() - IUCV handler to process a connection request.
* @path: Pending path (struct iucv_path)
* @ipvmid: Originator z/VM system identifier
* @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 check to determine if the pending
* path belongs to a terminal managed by this HVC backend.
* If the check is successful, then an additional check is done to ensure
* that a terminal cannot be accessed multiple times (only one connection
* to a terminal is allowed). In that particular case, the pending path is
* severed. If it is the first connection, the pending path is accepted and
* associated to the struct hvc_iucv_private. The iucv state is updated to
* reflect that a communication path has been established.
* 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 the path belongs to a terminal managed by the this HVC backend;
* 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
......@@ -672,7 +647,6 @@ static int hvc_iucv_path_pending(struct iucv_path *path,
priv = hvc_iucv_table[i];
break;
}
if (!priv)
return -ENODEV;
......@@ -719,8 +693,7 @@ out_path_handled:
* sets the iucv state to IUCV_SEVERED for the associated struct
* hvc_iucv_private instance. Later, the IUCV_SEVERED state triggers a tty
* hangup (hvc_iucv_get_chars() / hvc_iucv_write()).
*
* If tty portion of the HVC is closed then clean up the outqueue in addition.
* If tty portion of the HVC is closed, clean up the outqueue.
*
* Locking: struct hvc_iucv_private->lock
*/
......@@ -755,9 +728,9 @@ static void hvc_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
* @path: Pending path (struct iucv_path)
* @msg: Pointer to the IUCV message
*
* The function stores an incoming message on the input queue for later
* The function puts an incoming message on the input queue for later
* processing (by hvc_iucv_get_chars() / hvc_iucv_write()).
* However, if the tty has not yet been opened, the message is rejected.
* If the tty has not yet been opened, the message is rejected.
*
* Locking: struct hvc_iucv_private->lock
*/
......@@ -773,6 +746,7 @@ static void hvc_iucv_msg_pending(struct iucv_path *path,
return;
}
spin_lock(&priv->lock);
/* reject messages if tty has not yet been opened */
......@@ -791,7 +765,7 @@ static void hvc_iucv_msg_pending(struct iucv_path *path,
list_add_tail(&rb->list, &priv->tty_inqueue);
hvc_kick(); /* wake up hvc console thread */
hvc_kick(); /* wake up hvc thread */
unlock_return:
spin_unlock(&priv->lock);
......@@ -802,10 +776,10 @@ unlock_return:
* @path: Pending path (struct iucv_path)
* @msg: Pointer to the IUCV message
*
* The function is called upon completion of message delivery and the
* message is removed from the outqueue. Additional delivery information
* can be found in msg->audit: rejected messages (0x040000 (IPADRJCT)) and
* purged messages (0x010000 (IPADPGNR)).
* 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
*/
......@@ -841,8 +815,8 @@ static struct hv_ops hvc_iucv_ops = {
* hvc_iucv_alloc() - Allocates a new struct hvc_iucv_private instance
* @id: hvc_iucv_table index
*
* This function allocates a new hvc_iucv_private struct and put the
* instance into hvc_iucv_table at index @id.
* 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)
......@@ -867,7 +841,7 @@ static int __init hvc_iucv_alloc(int id)
return -ENOMEM;
}
/* Finally allocate hvc */
/* finally allocate hvc */
priv->hvc = hvc_alloc(HVC_IUCV_MAGIC + id, /* PAGE_SIZE */
HVC_IUCV_MAGIC + id, &hvc_iucv_ops, 256);
if (IS_ERR(priv->hvc)) {
......@@ -877,7 +851,7 @@ static int __init hvc_iucv_alloc(int id)
return rc;
}
/* kick khvcd thread; instead of using polling */
/* notify HVC thread instead of using polling */
priv->hvc->irq_requested = 1;
/* setup iucv related information */
......@@ -890,7 +864,7 @@ static int __init hvc_iucv_alloc(int id)
}
/**
* hvc_iucv_init() - Initialization of HVC backend for z/VM IUCV
* hvc_iucv_init() - z/VM IUCV HVC device driver initialization
*/
static int __init hvc_iucv_init(void)
{
......@@ -929,7 +903,7 @@ static int __init hvc_iucv_init(void)
rc = hvc_iucv_alloc(i);
if (rc) {
pr_err("Creating a new HVC terminal device "
"failed with error code=%d\n", rc);
"failed with error code=%d\n", rc);
goto out_error_hvc;
}
}
......
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