[S390] hvc_iucv: Limit rate of outgoing IUCV messages
This patch introduces a send buffer to limit outgoing IUCV messages up to
a maximum of 25 IUCV messages per second.
If no communication path to a IUCV HVC terminal exist, any data written to
the terminal is discarded.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/char/hvc_iucv.c b/drivers/char/hvc_iucv.c
index a80d922..a23f7e8 100644
--- a/drivers/char/hvc_iucv.c
+++ b/drivers/char/hvc_iucv.c
@@ -12,9 +12,11 @@
#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"
@@ -37,7 +39,7 @@
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));
@@ -60,6 +62,12 @@
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 */
};
@@ -318,57 +326,118 @@
}
/**
- * 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.
* @buf: Pointer to an buffer to read data from
@@ -385,7 +454,7 @@
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;
@@ -394,10 +463,10 @@
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;
}
/**
@@ -441,6 +510,46 @@
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);
}
/**
@@ -471,6 +580,8 @@
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
@@ -510,6 +621,8 @@
if (!priv)
return;
+ flush_sndbuf_sync(priv);
+
spin_lock_bh(&priv->lock);
path = priv->path; /* save reference to IUCV path */
priv->path = NULL;
@@ -588,6 +701,9 @@
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;
@@ -615,15 +731,18 @@
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) */
@@ -648,6 +767,12 @@
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 */
@@ -656,7 +781,7 @@
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);
@@ -666,7 +791,7 @@
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);
@@ -697,6 +822,7 @@
list_move(&ent->list, &list_remove);
break;
}
+ wake_up(&priv->sndbuf_waitq);
spin_unlock(&priv->lock);
destroy_tty_buffer_list(&list_remove);
}
@@ -732,16 +858,28 @@
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);
@@ -759,8 +897,8 @@
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;
}
@@ -774,16 +912,14 @@
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;
}
@@ -792,8 +928,8 @@
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;
}
}
@@ -801,7 +937,8 @@
/* 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;
}