[S390] hvc_iucv: Limit rate of outgoing IUCV messages

#include <linux/types.h>

#include <asm/ebcdic.h>

#include <linux/delay.h>

#include <linux/mempool.h>

#include <linux/module.h>

#include <linux/tty.h>

#include <linux/wait.h>

#include <net/iucv/iucv.h>

#include "hvc_console.h"

struct iucv_tty_msg {

	u8	version;		/* Message version */

	u8	type;			/* Message type */

#define MSG_MAX_DATALEN		(~(u16)0)

#define MSG_MAX_DATALEN		((u16)(~0))

	u16	datalen;		/* Payload length */

	u8	data[];			/* Payload buffer */

} __attribute__((packed));

	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 */

};

}

/**

 * hvc_iucv_send() - Send an IUCV message containing terminal data.

 * hvc_iucv_queue() - Buffer terminal data for sending.

 * @priv:	Pointer to struct hvc_iucv_private instance.

 * @buf:	Buffer containing data to send.

 * @size:	Size of buffer and amount of data to send.

 * @count:	Size of buffer and amount of data to send.

 *

 * If an IUCV communication path is established, the function copies the buffer

 * data to a newly allocated struct iucv_tty_buffer element, sends the data and

 * puts the element to the outqueue.

 * 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 there is no IUCV communication path established, the function returns 0.

 * 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).

 */

static int hvc_iucv_send(struct hvc_iucv_private *priv, const char *buf,

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 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.

 */

static int hvc_iucv_send(struct hvc_iucv_private *priv)

{

	struct iucv_tty_buffer *sb;

	int rc;

	u16 len;

	int rc, len;

	if (priv->iucv_state == IUCV_SEVERED)

		return -EPIPE;

	if (priv->iucv_state == IUCV_DISCONN)

		return 0;

		return -EIO;

	len = min_t(u16, MSG_MAX_DATALEN, count);

	if (!priv->sndbuf_len)

		return 0;

	/* allocate internal buffer to store msg data and also compute total

	 * message length */

	sb = alloc_tty_buffer(len, GFP_ATOMIC);

	sb = alloc_tty_buffer(priv->sndbuf_len, GFP_ATOMIC);

	if (!sb)

		return -ENOMEM;

	sb->mbuf->datalen = len;

	memcpy(sb->mbuf->data, buf, len);

	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 = 0;

	}

	len = priv->sndbuf_len;

	priv->sndbuf_len = 0;

	return len;

}

/**

 * 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.

 */

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;

	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.

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 sent;

	int queued;

	if (count <= 0)

		return 0;

		return -ENODEV;

	spin_lock(&priv->lock);

	sent = hvc_iucv_send(priv, buf, count);

	queued = hvc_iucv_queue(priv, buf, count);

	spin_unlock(&priv->lock);

	return sent;

	return queued;

}

/**

	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);

}

/**

	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]), then we have to

	if (!priv)

		return;

	flush_sndbuf_sync(priv);

	spin_lock_bh(&priv->lock);

	path = priv->path;		/* save reference to IUCV path */

	priv->path = NULL;

	priv->path = path;

	priv->iucv_state = IUCV_CONNECTED;

	/* flush buffered output data... */

	schedule_delayed_work(&priv->sndbuf_work, 5);

out_path_handled:

	spin_unlock(&priv->lock);

	return 0;

	spin_lock(&priv->lock);

	priv->iucv_state = IUCV_SEVERED;

	/* NOTE: If the tty has not yet been opened by a getty program

	 *	 (e.g. to see console messages), then cleanup the

	 *	 hvc_iucv_private structure to allow re-connects.

	/* 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, the get_chars() callback returns

	 *	 -EPIPE to signal the hvc console layer to hang up the tty. */

	 * 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

		hvc_kick();

	spin_unlock(&priv->lock);

	/* finally sever path (outside of priv->lock due to lock ordering) */

	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 */

		goto unlock_return;

	}

	/* allocate buffer an empty buffer element */

	/* allocate tty buffer to save iucv msg only */

	rb = alloc_tty_buffer(0, GFP_ATOMIC);

	if (!rb) {

		iucv_message_reject(path, msg);

	list_add_tail(&rb->list, &priv->tty_inqueue);

	hvc_kick();	/* wakup hvc console thread */

	hvc_kick();	/* wake up hvc console thread */

unlock_return:

	spin_unlock(&priv->lock);

			list_move(&ent->list, &list_remove);

			break;

		}

	wake_up(&priv->sndbuf_waitq);

	spin_unlock(&priv->lock);

	destroy_tty_buffer_list(&list_remove);

}

	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;

	}

	/* Finally allocate hvc */

	priv->hvc = hvc_alloc(HVC_IUCV_MAGIC + id,

			      HVC_IUCV_MAGIC + id, &hvc_iucv_ops, PAGE_SIZE);

	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;

	}

	/* kick khvcd 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);

	int rc, i;

	if (!MACHINE_IS_VM) {

		pr_warning("The z/VM IUCV Hypervisor console cannot be "

			   "used without z/VM.\n");

		pr_info("The z/VM IUCV HVC device driver cannot "

			   "be used without z/VM\n");

		return -ENODEV;

	}

					   sizeof(struct iucv_tty_buffer),

					   0, 0, NULL);

	if (!hvc_iucv_buffer_cache) {

		pr_err("Not enough memory for driver initialization "

			"(rs=%d).\n", 1);

		pr_err("Allocating memory failed with reason code=%d\n", 1);

		return -ENOMEM;

	}

	hvc_iucv_mempool = mempool_create_slab_pool(MEMPOOL_MIN_NR,

						    hvc_iucv_buffer_cache);

	if (!hvc_iucv_mempool) {

		pr_err("Not enough memory for driver initialization "

			"(rs=%d).\n", 2);

		pr_err("Allocating memory failed with reason code=%d\n", 2);

		kmem_cache_destroy(hvc_iucv_buffer_cache);

		return -ENOMEM;

	}

	for (i = 0; i < hvc_iucv_devices; i++) {

		rc = hvc_iucv_alloc(i);

		if (rc) {

			pr_err("Could not create new z/VM IUCV HVC backend "

				"rc=%d.\n", 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("Could not register iucv handler (rc=%d).\n", rc);

		pr_err("Registering IUCV handlers failed with error code=%d\n",

			rc);

		goto out_error_iucv;

	}