[S390] pm: hvc_iucv power management callbacks
authorHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Tue, 16 Jun 2009 08:30:45 +0000 (10:30 +0200)
committerMartin Schwidefsky <schwidefsky@de.ibm.com>
Tue, 16 Jun 2009 08:31:19 +0000 (10:31 +0200)
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IUCV communication path are no longer valid when the z/VM guest is halted.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>
drivers/char/hvc_iucv.c

index 54481a8877699d40d22d3afceded64d70365cbe0..86105efb4eb6cb948314a69b3b754ffdc290771a 100644 (file)
@@ -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>
  */
@@ -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>
@@ -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 {
@@ -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);
+       }
 }
 
 /**
@@ -735,11 +798,8 @@ out_path_handled:
  * @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
  */
@@ -747,33 +807,7 @@ 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);
 }
 
 /**
@@ -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 = {
@@ -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
@@ -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 */
@@ -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);
 }
 
 /**
@@ -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);
@@ -1183,15 +1302,14 @@ out_error_iucv:
        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;
 }