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[S390] pm: hvc_iucv power management callbacks
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The patch adds supporting for suspending and resuming IUCV HVC terminal
devices from disk. The obligatory Linux device driver interfaces has
been added by registering a device driver on the IUCV bus.
For each IUCV HVC terminal device the driver creates a respective device
on the IUCV bus.

To support suspend and resume, the PM freeze callback severs any established
IUCV communication path and triggers a HVC tty hang-up when the system image
is restored.
IUCV communication path are no longer valid when the z/VM guest is halted.

The device driver initialization has been updated to register devices and
the a new routine has been extracted to facilitate the hang-up of IUCV HVC
terminal devices.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Hendrik Brueckner authored and Martin Schwidefsky committed Jun 16, 2009
1 parent c23cad9 commit 0259162
Showing 1 changed file with 161 additions and 43 deletions.
204 changes: 161 additions & 43 deletions drivers/char/hvc_iucv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@
* This HVC device driver provides terminal access using
* z/VM IUCV communication paths.
*
* Copyright IBM Corp. 2008
* Copyright IBM Corp. 2008, 2009
*
* Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
*/
Expand All @@ -15,6 +15,7 @@
#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>
Expand Down Expand Up @@ -74,6 +75,7 @@ struct hvc_iucv_private {
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 */
};

struct iucv_tty_buffer {
Expand Down Expand Up @@ -542,7 +544,68 @@ static void flush_sndbuf_sync(struct hvc_iucv_private *priv)

if (sync_wait)
wait_event_timeout(priv->sndbuf_waitq,
tty_outqueue_empty(priv), HZ);
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);
}
}

/**
Expand Down Expand Up @@ -735,45 +798,16 @@ static int hvc_iucv_path_pending(struct iucv_path *path,
* @ipuser: User specified data for this path
* (AF_IUCV: port/service name and originator port)
*
* The function also severs the path (as required by the IUCV protocol) and
* 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, clean up the outqueue.
* 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[16])
{
struct hvc_iucv_private *priv = path->private;

spin_lock(&priv->lock);
priv->iucv_state = IUCV_SEVERED;

/* If the tty has not yet been opened, clean up the hvc_iucv_private
* structure to allow re-connects.
* This is also done for our console device because console hangups
* are handled specially and no notifier is called by HVC.
* The tty session is active (TTY_OPEN) and ready for re-connects...
*
* If it has been opened, let get_chars() return -EPIPE to signal the
* HVC layer to hang up the tty.
* If so, we need to wake up the HVC thread to call get_chars()...
*/
priv->path = NULL;
if (priv->tty_state == TTY_CLOSED)
hvc_iucv_cleanup(priv);
else
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) */
iucv_path_sever(path, ipuser);
iucv_path_free(path);
hvc_iucv_hangup(priv);
}

/**
Expand Down Expand Up @@ -853,6 +887,37 @@ static void hvc_iucv_msg_complete(struct iucv_path *path,
destroy_tty_buffer_list(&list_remove);
}

/**
* hvc_iucv_pm_freeze() - Freeze PM callback
* @dev: IUVC HVC terminal device
*
* Sever an established IUCV communication path and
* trigger a hang-up of the underlying HVC terminal.
*/
static int hvc_iucv_pm_freeze(struct device *dev)
{
struct hvc_iucv_private *priv = dev_get_drvdata(dev);

local_bh_disable();
hvc_iucv_hangup(priv);
local_bh_enable();

return 0;
}

/**
* hvc_iucv_pm_restore_thaw() - Thaw and restore PM callback
* @dev: IUVC HVC terminal device
*
* Wake up the HVC thread to trigger hang-up and respective
* HVC back-end notifier invocations.
*/
static int hvc_iucv_pm_restore_thaw(struct device *dev)
{
hvc_kick();
return 0;
}


/* HVC operations */
static struct hv_ops hvc_iucv_ops = {
Expand All @@ -863,6 +928,20 @@ static struct hv_ops hvc_iucv_ops = {
.notifier_hangup = hvc_iucv_notifier_hangup,
};

/* Suspend / resume device operations */
static struct dev_pm_ops hvc_iucv_pm_ops = {
.freeze = hvc_iucv_pm_freeze,
.thaw = hvc_iucv_pm_restore_thaw,
.restore = hvc_iucv_pm_restore_thaw,
};

/* IUCV HVC device driver */
static struct device_driver hvc_iucv_driver = {
.name = KMSG_COMPONENT,
.bus = &iucv_bus,
.pm = &hvc_iucv_pm_ops,
};

/**
* hvc_iucv_alloc() - Allocates a new struct hvc_iucv_private instance
* @id: hvc_iucv_table index
Expand Down Expand Up @@ -897,14 +976,12 @@ static int __init hvc_iucv_alloc(int id, unsigned int is_console)
/* set console flag */
priv->is_console = is_console;

/* finally allocate hvc */
/* 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);
free_page((unsigned long) priv->sndbuf);
kfree(priv);
return rc;
goto out_error_hvc;
}

/* notify HVC thread instead of using polling */
Expand All @@ -915,8 +992,45 @@ static int __init hvc_iucv_alloc(int id, unsigned int is_console)
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->driver = &hvc_iucv_driver;
priv->dev->release = (void (*)(struct device *)) kfree;
rc = device_register(priv->dev);
if (rc) {
kfree(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);
}

/**
Expand Down Expand Up @@ -1109,6 +1223,11 @@ static int __init hvc_iucv_init(void)
goto out_error;
}

/* register IUCV HVC device driver */
rc = driver_register(&hvc_iucv_driver);
if (rc)
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);
Expand Down Expand Up @@ -1183,15 +1302,14 @@ static int __init hvc_iucv_init(void)
iucv_unregister(&hvc_iucv_handler, 0);
out_error_hvc:
for (i = 0; i < hvc_iucv_devices; i++)
if (hvc_iucv_table[i]) {
if (hvc_iucv_table[i]->hvc)
hvc_remove(hvc_iucv_table[i]->hvc);
kfree(hvc_iucv_table[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:
if (hvc_iucv_filter)
kfree(hvc_iucv_filter);
hvc_iucv_devices = 0; /* ensure that we do not provide any device */
return rc;
}
Expand Down

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