[ANNOUNCE 1b/6] Linux-iSCSI High-Performance Initiator

[ANNOUNCE 1b/6] Linux-iSCSI High-Performance Initiator

[Alex Aizman]

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For the start of this thread please refer to:

http://marc.theaimsgroup.com/?l=linux-kernel&m=111327337005048&w=2
and
http://marc.theaimsgroup.com/?l=linux-kernel&m=111328256211837&w=2

Regards,

The combined open-iscsi and linux-iscsi teams


              SCSI LLDD, the 2nd part:
              - iscsi_if.c (iSCSI open interface over netlink, iSCSI 
generic transport module).

              Signed-off-by: Alex Aizman <itn780@yahoo.com>
              Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>



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diff -Nru --exclude Kconfig --exclude Makefile linux-2.6.12-rc2.orig/drivers/scsi/iscsi_if.c linux-2.6.12-rc2.dima/drivers/scsi/iscsi_if.c
--- linux-2.6.12-rc2.orig/drivers/scsi/iscsi_if.c	1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.12-rc2.dima/drivers/scsi/iscsi_if.c	2005-04-11 18:13:12.000000000 -0700
@@ -0,0 +1,818 @@
+/*
+ * iSCSI Initiator Kernel/User Interface
+ *
+ * Copyright (C) 2004 Dmitry Yusupov, Alex Aizman
+ * maintained by open-iscsi@googlegroups.com
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * See the file COPYING included with this distribution for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/mempool.h>
+#include <net/tcp.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_transport.h>
+#ifdef CONFIG_SCSI_ISCSI_ATTRS
+#include <scsi/scsi_transport_iscsi.h>
+#endif
+#include <scsi/iscsi_iftrans.h>
+#include <scsi/iscsi_ifev.h>
+
+MODULE_AUTHOR("Dmitry Yusupov <dmitry_yus@yahoo.com>, "
+	      "Alex Aizman <itn780@yahoo.com>");
+MODULE_DESCRIPTION("Open-iSCSI Interface");
+MODULE_LICENSE("GPL");
+
+static struct iscsi_transport *transport_table[ISCSI_TRANSPORT_MAX];
+static struct sock *nls;
+static int daemon_pid;
+DECLARE_MUTEX(callsema);
+
+struct mempool_zone {
+	mempool_t *pool;
+	volatile int allocated;
+	int size;
+	int max;
+	int hiwat;
+	struct list_head freequeue;
+	spinlock_t freelock;
+};
+
+static struct mempool_zone z_reply;
+
+#define Z_REPLY		0
+#define Z_SIZE_REPLY	NLMSG_SPACE(sizeof(struct iscsi_uevent))
+#define Z_MAX_REPLY	8
+#define Z_HIWAT_REPLY	6
+
+#define Z_PDU		1
+#define Z_SIZE_PDU	NLMSG_SPACE(sizeof(struct iscsi_uevent) + \
+				    sizeof(struct iscsi_hdr) + \
+				    DEFAULT_MAX_RECV_DATA_SEGMENT_LENGTH)
+#define Z_MAX_PDU	8
+#define Z_HIWAT_PDU	6
+
+#define Z_ERROR		2
+#define Z_SIZE_ERROR	NLMSG_SPACE(sizeof(struct iscsi_uevent))
+#define Z_MAX_ERROR	16
+#define Z_HIWAT_ERROR	12
+
+#define zone_init(_zp, _zone) ({ \
+	(_zp)->pool = mempool_create(Z_MAX_##_zone, \
+			mempool_zone_alloc_skb, mempool_zone_free_skb, \
+			(void*)(_zp)); \
+	if ((_zp)->pool) { \
+		(_zp)->max = Z_MAX_##_zone; \
+		(_zp)->size = Z_SIZE_##_zone; \
+		(_zp)->hiwat = Z_HIWAT_##_zone; \
+		INIT_LIST_HEAD(&(_zp)->freequeue); \
+		spin_lock_init(&(_zp)->freelock); \
+		(_zp)->allocated = 0; \
+	} \
+	(_zp)->pool; \
+})
+
+struct iscsi_if_cnx {
+	struct list_head item;		/* item in cnxlist */
+	struct list_head snxitem;	/* item in snx->connections */
+	iscsi_cnx_t cp_cnx;
+	iscsi_cnx_t dp_cnx;
+	volatile int active;
+	struct Scsi_Host *host;		/* originated shost */
+	struct iscsi_transport *transport;
+	struct mempool_zone z_error;
+	struct mempool_zone z_pdu;
+	struct list_head freequeue;
+};
+LIST_HEAD(cnxlist);
+spinlock_t cnxlock;
+
+struct iscsi_if_snx {
+	struct list_head item;	/* item in snxlist */
+	struct list_head connections;
+	iscsi_snx_t cp_snx;
+	iscsi_snx_t dp_snx;
+	struct iscsi_transport *transport;
+};
+LIST_HEAD(snxlist);
+spinlock_t snxlock;
+
+#define H_TYPE_CP	0
+#define H_TYPE_DP	1
+#define H_TYPE_HOST	2
+static struct iscsi_if_cnx*
+iscsi_if_find_cnx(uint64_t key, int type)
+{
+	unsigned long flags;
+	struct iscsi_if_cnx *cnx;
+
+	spin_lock_irqsave(&cnxlock, flags);
+	list_for_each_entry(cnx, &cnxlist, item) {
+		if ((type == H_TYPE_DP && cnx->dp_cnx == key) ||
+		    (type == H_TYPE_CP && cnx->cp_cnx == key) ||
+		    (type == H_TYPE_HOST && cnx->host == iscsi_ptr(key))) {
+			spin_unlock_irqrestore(&cnxlock, flags);
+			return cnx;
+		}
+	}
+	spin_unlock_irqrestore(&cnxlock, flags);
+	return NULL;
+}
+
+static struct iscsi_if_snx*
+iscsi_if_find_snx(struct iscsi_transport *t)
+{
+	unsigned long flags;
+	struct iscsi_if_snx *snx;
+
+	spin_lock_irqsave(&snxlock, flags);
+	list_for_each_entry(snx, &snxlist, item) {
+		if (snx->transport == t) {
+			spin_unlock_irqrestore(&snxlock, flags);
+			return snx;
+		}
+	}
+	spin_unlock_irqrestore(&snxlock, flags);
+	return NULL;
+}
+
+static int
+iscsi_if_transport_lookup(struct iscsi_transport *t)
+{
+	int i;
+
+	for (i=0; i < ISCSI_TRANSPORT_MAX; i++) {
+		if (transport_table[i] == t) {
+			return i;
+		}
+	}
+	return -1;
+}
+
+#ifdef CONFIG_SCSI_ISCSI_ATTRS
+static struct scsi_transport_template *iscsi_transportt;
+#define iscsi_transport_get_fn(_field, _param)				\
+static void								\
+iscsi_if_get_##_field (struct scsi_target *stgt)			\
+{									\
+	struct Scsi_Host *host = dev_to_shost(stgt->dev.parent);	\
+	struct iscsi_if_cnx *cnx = iscsi_if_find_cnx(			\
+				     iscsi_handle(host), H_TYPE_HOST);	\
+	if (cnx) {							\
+		uint32_t value = 0;					\
+		struct iscsi_transport *t =				\
+				iscsi_ptr(*(uint64_t *)host->hostdata);	\
+		t->get_param(cnx->dp_cnx, _param, &value);		\
+		iscsi_##_field(stgt) = value;				\
+	} else								\
+		iscsi_##_field(stgt) = 0;				\
+}
+
+iscsi_transport_get_fn(initial_r2t, ISCSI_PARAM_INITIAL_R2T_EN);
+iscsi_transport_get_fn(immediate_data, ISCSI_PARAM_IMM_DATA_EN);
+iscsi_transport_get_fn(first_burst_len, ISCSI_PARAM_FIRST_BURST);
+iscsi_transport_get_fn(max_burst_len, ISCSI_PARAM_MAX_BURST);
+
+static struct iscsi_function_template iscsi_fnt = {
+	.get_initial_r2t	= iscsi_if_get_initial_r2t,
+	.show_initial_r2t	= 1,
+	.get_immediate_data	= iscsi_if_get_immediate_data,
+	.show_immediate_data	= 1,
+	.get_max_burst_len	= iscsi_if_get_max_burst_len,
+	.show_max_burst_len	= 1,
+	.get_first_burst_len	= iscsi_if_get_first_burst_len,
+	.show_first_burst_len	= 1,
+};
+#endif
+
+static void*
+mempool_zone_alloc_skb(unsigned int gfp_mask, void *pool_data)
+{
+	struct mempool_zone *zone = pool_data;
+
+	return alloc_skb(zone->size, gfp_mask);
+}
+
+static void
+mempool_zone_free_skb(void *element, void *pool_data)
+{
+	kfree_skb(element);
+}
+
+static void
+mempool_zone_complete(struct mempool_zone *zone)
+{
+	unsigned long flags;
+	struct list_head *lh, *n;
+
+	spin_lock_irqsave(&zone->freelock, flags);
+	list_for_each_safe(lh, n, &zone->freequeue) {
+		struct sk_buff *skb = (struct sk_buff *)((char *)lh -
+				offsetof(struct sk_buff, cb));
+		if (!skb_shared(skb)) {
+			list_del((void*)&skb->cb);
+			mempool_free(skb, zone->pool);
+			zone->allocated--;
+			BUG_ON(zone->allocated < 0);
+		}
+	}
+	spin_unlock_irqrestore(&zone->freelock, flags);
+}
+
+static struct sk_buff*
+mempool_zone_get_skb(struct mempool_zone *zone)
+{
+	struct sk_buff *skb;
+
+	if (zone->allocated < zone->max) {
+		skb = mempool_alloc(zone->pool, GFP_ATOMIC);
+		BUG_ON(!skb);
+		zone->allocated++;
+	} else
+		return NULL;
+
+	return skb;
+}
+
+static int
+iscsi_unicast_skb(struct mempool_zone *zone, struct sk_buff *skb)
+{
+	unsigned long flags;
+	int rc;
+
+	skb_get(skb);
+	rc = netlink_unicast(nls, skb, daemon_pid, MSG_DONTWAIT);
+	if (rc < 0) {
+		mempool_free(skb, zone->pool);
+		printk("iscsi: can not unicast skb (%d)\n", rc);
+		return rc;
+	}
+
+	spin_lock_irqsave(&zone->freelock, flags);
+	list_add((void*)&skb->cb, &zone->freequeue);
+	spin_unlock_irqrestore(&zone->freelock, flags);
+
+	return 0;
+}
+
+int iscsi_recv_pdu(iscsi_cnx_t cp_cnx, struct iscsi_hdr *hdr,
+				char *data, uint32_t data_size)
+{
+	struct nlmsghdr	*nlh;
+	struct sk_buff *skb;
+	struct iscsi_uevent *ev;
+	struct iscsi_if_cnx *cnx;
+	char *pdu;
+	int rc;
+	int len = NLMSG_SPACE(sizeof(*ev) + sizeof(struct iscsi_hdr) +
+			      data_size);
+
+	cnx = iscsi_if_find_cnx(cp_cnx, H_TYPE_CP);
+	BUG_ON(!cnx);
+
+	mempool_zone_complete(&cnx->z_pdu);
+
+	skb = mempool_zone_get_skb(&cnx->z_pdu);
+	if (!skb) {
+		iscsi_cnx_error(cp_cnx, ISCSI_ERR_CNX_FAILED);
+		printk("iscsi%d: can not deliver control PDU: OOM\n",
+		       cnx->host->host_no);
+		return -ENOMEM;
+	}
+
+	nlh = __nlmsg_put(skb, daemon_pid, 0, 0, (len - sizeof(*nlh)));
+	ev = NLMSG_DATA(nlh);
+	memset(ev, 0, sizeof(*ev));
+	ev->transport_handle = iscsi_handle(cnx->transport);
+	ev->type = ISCSI_KEVENT_RECV_PDU;
+	if (cnx->z_pdu.allocated >= cnx->z_pdu.hiwat)
+		ev->iferror = -ENOMEM;
+	ev->r.recv_req.cnx_handle = cp_cnx;
+	pdu = (char*)ev + sizeof(*ev);
+	memcpy(pdu, hdr, sizeof(struct iscsi_hdr));
+	memcpy(pdu + sizeof(struct iscsi_hdr), data, data_size);
+
+	rc =  iscsi_unicast_skb(&cnx->z_pdu, skb);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(iscsi_recv_pdu);
+
+void iscsi_cnx_error(iscsi_cnx_t cp_cnx, enum iscsi_err error)
+{
+	struct nlmsghdr	*nlh;
+	struct sk_buff	*skb;
+	struct iscsi_uevent *ev;
+	struct iscsi_if_cnx *cnx;
+	int len = NLMSG_SPACE(sizeof(*ev));
+
+	cnx = iscsi_if_find_cnx(cp_cnx, H_TYPE_CP);
+	BUG_ON(!cnx);
+
+	mempool_zone_complete(&cnx->z_error);
+
+	skb = mempool_zone_get_skb(&cnx->z_error);
+	if (!skb) {
+		printk("iscsi%d: gracefully ignored cnx error (%d)\n",
+		       cnx->host->host_no, error);
+		return;
+	}
+
+	nlh = __nlmsg_put(skb, daemon_pid, 0, 0, (len - sizeof(*nlh)));
+	ev = NLMSG_DATA(nlh);
+	ev->transport_handle = iscsi_handle(cnx->transport);
+	ev->type = ISCSI_KEVENT_CNX_ERROR;
+	if (cnx->z_error.allocated >= cnx->z_error.hiwat)
+		ev->iferror = -ENOMEM;
+	ev->r.cnxerror.error = error;
+	ev->r.cnxerror.cnx_handle = cp_cnx;
+
+	iscsi_unicast_skb(&cnx->z_error, skb);
+
+	printk("iscsi%d: detected cnx error (%d)\n", cnx->host->host_no, error);
+}
+EXPORT_SYMBOL_GPL(iscsi_cnx_error);
+
+static int
+iscsi_if_send_reply(int pid, int seq, int type, int done, int multi,
+		      void *payload, int size)
+{
+	struct sk_buff	*skb;
+	struct nlmsghdr	*nlh;
+	int len = NLMSG_SPACE(size);
+	int flags = multi ? NLM_F_MULTI : 0;
+	int t = done ? NLMSG_DONE  : type;
+
+	mempool_zone_complete(&z_reply);
+
+	skb = mempool_zone_get_skb(&z_reply);
+	/*
+	 * user is supposed to react on iferror == -ENOMEM;
+	 * see iscsi_if_rx().
+	 */
+	BUG_ON(!skb);
+
+	nlh = __nlmsg_put(skb, pid, seq, t, (len - sizeof(*nlh)));
+	nlh->nlmsg_flags = flags;
+	memcpy(NLMSG_DATA(nlh), payload, size);
+	return iscsi_unicast_skb(&z_reply, skb);
+}
+
+/*
+ * iSCSI Session's hostdata organization:
+ *
+ *    /------------------\ <== host->hostdata
+ *    | transport        |
+ *    |------------------| <== iscsi_hostdata(host->hostdata)
+ *    | transport's data |
+ *    |------------------| <== hostdata_snx(host->hostdata)
+ *    | interface's data |
+ *    \------------------/
+ */
+
+#define hostdata_privsize(_t)	(sizeof(unsigned long) + _t->hostdata_size + \
+				 _t->hostdata_size % sizeof(unsigned long) + \
+				 sizeof(struct iscsi_if_snx))
+
+#define hostdata_snx(_hostdata)	((void*)_hostdata + sizeof(unsigned long) + \
+			((struct iscsi_transport *) \
+			 iscsi_ptr(*(uint64_t *)_hostdata))->hostdata_size)
+
+static int
+iscsi_if_create_snx(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+{
+	struct iscsi_if_snx *snx;
+	struct Scsi_Host *host;
+	unsigned long flags;
+	int res;
+
+	if (!try_module_get(transport->owner))
+		return -EPERM;
+
+	host = scsi_host_alloc(transport->host_template,
+			       hostdata_privsize(transport));
+	if (!host) {
+		ev->r.c_session_ret.handle = iscsi_handle(NULL);
+		printk("iscsi: can not allocate SCSI host for session %p\n",
+			iscsi_ptr(ev->u.c_session.session_handle));
+		module_put(transport->owner);
+		return -ENOMEM;
+	}
+	host->max_id = 1;
+	host->max_channel = 0;
+	host->max_lun = transport->max_lun;
+	host->max_cmd_len = transport->max_cmd_len;
+#ifdef CONFIG_SCSI_ISCSI_ATTRS
+	host->transportt = iscsi_transportt;
+#endif
+
+	/* store struct iscsi_transport in hostdata */
+	*(uint64_t*)host->hostdata = ev->transport_handle;
+
+	ev->r.c_session_ret.handle = transport->create_session(
+	       ev->u.c_session.session_handle, ev->u.c_session.initial_cmdsn,
+	       host);
+	if (ev->r.c_session_ret.handle == iscsi_handle(NULL)) {
+		scsi_host_put(host);
+		module_put(transport->owner);
+		return 0;
+	}
+
+	/* host_no becomes assigned SID */
+	ev->r.c_session_ret.sid = host->host_no;
+	/* initialize snx */
+	snx = hostdata_snx(host->hostdata);
+	INIT_LIST_HEAD(&snx->connections);
+	snx->cp_snx = ev->u.c_session.session_handle;
+	snx->dp_snx = ev->r.c_session_ret.handle;
+	snx->transport = transport;
+
+	res = scsi_add_host(host, NULL);
+	if (res) {
+		transport->destroy_session(ev->r.c_session_ret.handle);
+		scsi_host_put(host);
+		ev->r.c_session_ret.handle = iscsi_handle(NULL);
+		printk("iscsi%d: can not add host (%d)\n",
+		       host->host_no, res);
+		module_put(transport->owner);
+		return res;
+	}
+
+	/* add this session to the list of active sessions */
+	spin_lock_irqsave(&snxlock, flags);
+	list_add(&snx->item, &snxlist);
+	spin_unlock_irqrestore(&snxlock, flags);
+	return 0;
+}
+
+static int
+iscsi_if_destroy_snx(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+{
+	struct Scsi_Host *host;
+	struct iscsi_if_snx *snx;
+	unsigned long flags;
+	struct iscsi_if_cnx *cnx;
+
+	host = scsi_host_lookup(ev->u.d_session.sid);
+	if (host == ERR_PTR(-ENXIO))
+		return -EEXIST;
+	snx = hostdata_snx(host->hostdata);
+
+	/* check if we have active connections */
+	spin_lock_irqsave(&cnxlock, flags);
+	list_for_each_entry(cnx, &snx->connections, snxitem) {
+		if (cnx->active) {
+			printk("iscsi%d: can not destroy session: "
+			       "has active connection (%p)\n",
+			       host->host_no, iscsi_ptr(cnx->dp_cnx));
+			spin_unlock_irqrestore(&cnxlock, flags);
+			return -EIO;
+		}
+	}
+	spin_unlock_irqrestore(&cnxlock, flags);
+
+	scsi_remove_host(host);
+	transport->destroy_session(ev->u.d_session.session_handle);
+
+	/* now free connections */
+	spin_lock_irqsave(&cnxlock, flags);
+	list_for_each_entry(cnx, &snx->connections, snxitem) {
+		list_del(&cnx->item);
+		mempool_destroy(cnx->z_pdu.pool);
+		mempool_destroy(cnx->z_error.pool);
+		kfree(cnx);
+	}
+	spin_unlock_irqrestore(&cnxlock, flags);
+
+	/* remove this session from the list of active sessions */
+	spin_lock_irqsave(&snxlock, flags);
+	list_del(&snx->item);
+	spin_unlock_irqrestore(&snxlock, flags);
+
+	scsi_host_put(host);
+	module_put(transport->owner);
+	return 0;
+}
+
+static int
+iscsi_if_create_cnx(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+{
+	struct iscsi_if_snx *snx;
+	struct Scsi_Host *host;
+	struct iscsi_if_cnx *cnx;
+
+	host = scsi_host_lookup(ev->u.c_cnx.sid);
+	if (host == ERR_PTR(-ENXIO))
+		return -EEXIST;
+	snx = hostdata_snx(host->hostdata);
+
+	cnx = kmalloc(sizeof(struct iscsi_if_cnx), GFP_KERNEL);
+	if (!cnx)
+		return -ENOMEM;
+	memset(cnx, 0, sizeof(struct iscsi_if_cnx));
+	cnx->host = host;
+	snx->transport = transport;
+
+	if (!zone_init(&cnx->z_pdu, PDU)) {
+		printk("iscsi%d: can not allocate pdu zone for new cnx\n",
+		       host->host_no);
+		kfree(cnx);
+		return -ENOMEM;
+	}
+	if (!zone_init(&cnx->z_error, ERROR)) {
+		printk("iscsi%d: can not allocate error zone for new cnx\n",
+		       host->host_no);
+		mempool_destroy(cnx->z_pdu.pool);
+		kfree(cnx);
+		return -ENOMEM;
+	}
+
+	ev->r.handle = transport->create_cnx(ev->u.c_cnx.session_handle,
+			     ev->u.c_cnx.cnx_handle, ev->u.c_cnx.cid);
+	if (!ev->r.handle) {
+		mempool_destroy(cnx->z_pdu.pool);
+		mempool_destroy(cnx->z_error.pool);
+		kfree(cnx);
+	} else {
+		unsigned long flags;
+
+		cnx->cp_cnx = ev->u.c_cnx.cnx_handle;
+		cnx->dp_cnx = ev->r.handle;
+		spin_lock_irqsave(&cnxlock, flags);
+		list_add(&cnx->item, &cnxlist);
+		list_add(&cnx->snxitem, &snx->connections);
+		spin_unlock_irqrestore(&cnxlock, flags);
+		cnx->active = 1;
+	}
+	return 0;
+}
+
+static int
+iscsi_if_destroy_cnx(struct iscsi_transport *transport, struct iscsi_uevent *ev)
+{
+	unsigned long flags;
+	struct iscsi_if_cnx *cnx;
+
+	cnx = iscsi_if_find_cnx(ev->u.d_cnx.cnx_handle, H_TYPE_DP);
+	if (!cnx)
+		return -EEXIST;
+
+	transport->destroy_cnx(ev->u.d_cnx.cnx_handle);
+	cnx->active = 0;
+
+	spin_lock_irqsave(&cnxlock, flags);
+	list_del(&cnx->snxitem);
+	spin_unlock_irqrestore(&cnxlock, flags);
+	return 0;
+}
+
+static int
+iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+{
+	int err = 0;
+	struct iscsi_uevent *ev = NLMSG_DATA(nlh);
+	struct iscsi_transport *transport = iscsi_ptr(ev->transport_handle);
+
+	if (nlh->nlmsg_type != ISCSI_UEVENT_TRANS_LIST &&
+	    iscsi_if_transport_lookup(transport) < 0)
+		return -EEXIST;
+
+	daemon_pid = NETLINK_CREDS(skb)->pid;
+
+	switch (nlh->nlmsg_type) {
+	case ISCSI_UEVENT_TRANS_LIST: {
+		int i;
+		for (i=0; i < ISCSI_TRANSPORT_MAX; i++) {
+			if (transport_table[i]) {
+				ev->r.t_list.elements[i].handle =
+					iscsi_handle(transport_table[i]);
+				strncpy(ev->r.t_list.elements[i].name,
+					transport_table[i]->name,
+					ISCSI_TRANSPORT_NAME_MAXLEN);
+			} else
+				ev->r.t_list.elements[i].handle =
+					iscsi_handle(NULL);
+		}
+	      } break;
+	case ISCSI_UEVENT_CREATE_SESSION:
+		err = iscsi_if_create_snx(transport, ev);
+		break;
+	case ISCSI_UEVENT_DESTROY_SESSION:
+		err = iscsi_if_destroy_snx(transport, ev);
+		break;
+	case ISCSI_UEVENT_CREATE_CNX:
+		err = iscsi_if_create_cnx(transport, ev);
+		break;
+	case ISCSI_UEVENT_DESTROY_CNX:
+		err = iscsi_if_destroy_cnx(transport, ev);
+		break;
+	case ISCSI_UEVENT_BIND_CNX:
+		if (!iscsi_if_find_cnx(ev->u.b_cnx.cnx_handle, H_TYPE_DP))
+			return -EEXIST;
+		ev->r.retcode = transport->bind_cnx(
+			ev->u.b_cnx.session_handle,
+			ev->u.b_cnx.cnx_handle,
+			ev->u.b_cnx.transport_fd,
+			ev->u.b_cnx.is_leading);
+		break;
+	case ISCSI_UEVENT_SET_PARAM:
+		if (!iscsi_if_find_cnx(ev->u.set_param.cnx_handle, H_TYPE_DP))
+			return -EEXIST;
+		ev->r.retcode = transport->set_param(
+			ev->u.set_param.cnx_handle,
+			ev->u.set_param.param, ev->u.set_param.value);
+		break;
+	case ISCSI_UEVENT_START_CNX:
+		if (!iscsi_if_find_cnx(ev->u.start_cnx.cnx_handle, H_TYPE_DP))
+			return -EEXIST;
+		ev->r.retcode = transport->start_cnx(
+			ev->u.start_cnx.cnx_handle);
+		break;
+	case ISCSI_UEVENT_STOP_CNX:
+		if (!iscsi_if_find_cnx(ev->u.stop_cnx.cnx_handle, H_TYPE_DP))
+			return -EEXIST;
+		transport->stop_cnx(ev->u.stop_cnx.cnx_handle,
+			ev->u.stop_cnx.flag);
+		break;
+	case ISCSI_UEVENT_SEND_PDU:
+		if (!iscsi_if_find_cnx(ev->u.send_pdu.cnx_handle, H_TYPE_DP))
+			return -EEXIST;
+		ev->r.retcode = transport->send_pdu(
+		       ev->u.send_pdu.cnx_handle,
+		       (struct iscsi_hdr*)((char*)ev + sizeof(*ev)),
+		       (char*)ev + sizeof(*ev) + ev->u.send_pdu.hdr_size,
+			ev->u.send_pdu.data_size);
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+	return err;
+}
+
+/* Get message from skb (based on rtnetlink_rcv_skb).  Each message is
+ * processed by iscsi_if_recv_msg.  Malformed skbs with wrong length are
+ * discarded silently.  */
+static void
+iscsi_if_rx(struct sock *sk, int len)
+{
+	struct sk_buff *skb;
+
+	down(&callsema);
+	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
+		while (skb->len >= NLMSG_SPACE(0)) {
+			int err;
+			uint32_t rlen;
+			struct nlmsghdr	*nlh;
+			struct iscsi_uevent *ev;
+
+			nlh = (struct nlmsghdr *)skb->data;
+			if (nlh->nlmsg_len < sizeof(*nlh) ||
+			    skb->len < nlh->nlmsg_len) {
+				break;
+			}
+			ev = NLMSG_DATA(nlh);
+			rlen = NLMSG_ALIGN(nlh->nlmsg_len);
+			if (rlen > skb->len)
+				rlen = skb->len;
+			err = iscsi_if_recv_msg(skb, nlh);
+			if (err) {
+				ev->type = ISCSI_KEVENT_IF_ERROR;
+				ev->iferror = err;
+			}
+			do {
+				err = iscsi_if_send_reply(
+					NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq,
+					nlh->nlmsg_type, 0, 0, ev, sizeof(*ev));
+				if (z_reply.allocated >= z_reply.hiwat)
+					ev->iferror = -ENOMEM;
+			} while (err < 0 && err != -ECONNREFUSED);
+			skb_pull(skb, rlen);
+		}
+		kfree_skb(skb);
+	}
+	up(&callsema);
+}
+
+int iscsi_register_transport(struct iscsi_transport *t)
+{
+	int i;
+
+	BUG_ON(!t);
+	for (i=0; i < ISCSI_TRANSPORT_MAX; i++) {
+		if (transport_table[i] == t)
+			return -EEXIST;
+		if (!transport_table[i]) {
+			transport_table[i] = t;
+			printk("iscsi: registered transport (%d - %s)\n",
+			       i, t->name);
+			return 0;
+		}
+	}
+	return -EPERM;
+}
+EXPORT_SYMBOL_GPL(iscsi_register_transport);
+
+int iscsi_unregister_transport(struct iscsi_transport *t)
+{
+	int id;
+
+	BUG_ON(!t);
+	down(&callsema);
+	if (iscsi_if_find_snx(t)) {
+		up(&callsema);
+		return -EPERM;
+	}
+	id = iscsi_if_transport_lookup(t);
+	BUG_ON (id < 0);
+	transport_table[id] = NULL;
+	up(&callsema);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iscsi_unregister_transport);
+
+static int
+iscsi_rcv_nl_event(struct notifier_block *this,
+                 unsigned long event, void *ptr)
+{
+	struct netlink_notify *n = ptr;
+
+	if (event == NETLINK_URELEASE &&
+	    n->protocol == NETLINK_ISCSI && n->pid) {
+		struct iscsi_if_cnx *cnx;
+		unsigned long flags;
+
+		mempool_zone_complete(&z_reply);
+		spin_lock_irqsave(&cnxlock, flags);
+		list_for_each_entry(cnx, &cnxlist, item) {
+			mempool_zone_complete(&cnx->z_error);
+			mempool_zone_complete(&cnx->z_pdu);
+		}
+		spin_unlock_irqrestore(&cnxlock, flags);
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block iscsi_nl_notifier = {
+	.notifier_call	= iscsi_rcv_nl_event,
+};
+
+static int __init
+iscsi_if_init(void)
+{
+	spin_lock_init(&cnxlock);
+	spin_lock_init(&snxlock);
+
+	netlink_register_notifier(&iscsi_nl_notifier);
+	nls = netlink_kernel_create(NETLINK_ISCSI, iscsi_if_rx);
+	if (nls == NULL)
+		return -ENOBUFS;
+
+	if (!zone_init(&z_reply, REPLY)) {
+		sock_release(nls->sk_socket);
+		netlink_unregister_notifier(&iscsi_nl_notifier);
+		return -ENOMEM;
+	}
+
+#ifdef CONFIG_SCSI_ISCSI_ATTRS
+	iscsi_transportt = iscsi_attach_transport(&iscsi_fnt);
+	if (!iscsi_transportt) {
+		mempool_destroy(z_reply.pool);
+		sock_release(nls->sk_socket);
+		netlink_unregister_notifier(&iscsi_nl_notifier);
+		return -ENOMEM;
+	}
+#endif
+
+	printk(KERN_INFO "Open-iSCSI Interface, version "
+			ISCSI_VERSION_STR " variant (" ISCSI_DATE_STR ")\n");
+
+	return 0;
+}
+
+static void __exit
+iscsi_if_exit(void)
+{
+#ifdef CONFIG_SCSI_ISCSI_ATTRS
+	iscsi_release_transport(iscsi_transportt);
+#endif
+	mempool_destroy(z_reply.pool);
+	sock_release(nls->sk_socket);
+	netlink_unregister_notifier(&iscsi_nl_notifier);
+}
+
+module_init(iscsi_if_init);
+module_exit(iscsi_if_exit);