text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Witness Service client for CIFS
   *
   * Copyright (c) 2020 Samuel Cabrero <scabrero@suse.de>
   */
  
  #include <linux/kref.h>
  #include <net/genetlink.h>
  #include <uapi/linux/cifs/cifs_netlink.h>
  
  #include "cifs_swn.h"
  #include "cifsglob.h"
  #include "cifsproto.h"
  #include "fscache.h"
  #include "cifs_debug.h"
  #include "netlink.h"
  
  static DEFINE_IDR(cifs_swnreg_idr);
  static DEFINE_MUTEX(cifs_swnreg_idr_mutex);
  
  struct cifs_swn_reg {
  	int id;
  	struct kref ref_count;
  
  	const char *net_name;
  	const char *share_name;
  	bool net_name_notify;
  	bool share_name_notify;
  	bool ip_notify;
  
  	struct cifs_tcon *tcon;
  };
  
  static int cifs_swn_auth_info_krb(struct cifs_tcon *tcon, struct sk_buff *skb)
  {
  	int ret;
  
  	ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_KRB_AUTH);
  	if (ret < 0)
  		return ret;
  
  	return 0;
  }
  
  static int cifs_swn_auth_info_ntlm(struct cifs_tcon *tcon, struct sk_buff *skb)
  {
  	int ret;
  
  	if (tcon->ses->user_name != NULL) {
  		ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_USER_NAME, tcon->ses->user_name);
  		if (ret < 0)
  			return ret;
  	}
  
  	if (tcon->ses->password != NULL) {
  		ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_PASSWORD, tcon->ses->password);
  		if (ret < 0)
  			return ret;
  	}
  
  	if (tcon->ses->domainName != NULL) {
  		ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_DOMAIN_NAME, tcon->ses->domainName);
  		if (ret < 0)
  			return ret;
  	}
  
  	return 0;
  }
  
  /*
   * Sends a register message to the userspace daemon based on the registration.
   * The authentication information to connect to the witness service is bundled
   * into the message.
   */
  static int cifs_swn_send_register_message(struct cifs_swn_reg *swnreg)
  {
  	struct sk_buff *skb;
  	struct genlmsghdr *hdr;
  	enum securityEnum authtype;
  	struct sockaddr_storage *addr;
  	int ret;
  
  	skb = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
  	if (skb == NULL) {
  		ret = -ENOMEM;
  		goto fail;
  	}
  
  	hdr = genlmsg_put(skb, 0, 0, &cifs_genl_family, 0, CIFS_GENL_CMD_SWN_REGISTER);
  	if (hdr == NULL) {
  		ret = -ENOMEM;
  		goto nlmsg_fail;
  	}
  
  	ret = nla_put_u32(skb, CIFS_GENL_ATTR_SWN_REGISTRATION_ID, swnreg->id);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_NET_NAME, swnreg->net_name);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME, swnreg->share_name);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	/*
  	 * If there is an address stored use it instead of the server address, because we are
  	 * in the process of reconnecting to it after a share has been moved or we have been
  	 * told to switch to it (client move message). In these cases we unregister from the
  	 * server address and register to the new address when we receive the notification.
  	 */
  	if (swnreg->tcon->ses->server->use_swn_dstaddr)
  		addr = &swnreg->tcon->ses->server->swn_dstaddr;
  	else
  		addr = &swnreg->tcon->ses->server->dstaddr;
  
  	ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage), addr);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	if (swnreg->net_name_notify) {
  		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_NET_NAME_NOTIFY);
  		if (ret < 0)
  			goto nlmsg_fail;
  	}
  
  	if (swnreg->share_name_notify) {
  		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME_NOTIFY);
  		if (ret < 0)
  			goto nlmsg_fail;
  	}
  
  	if (swnreg->ip_notify) {
  		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_IP_NOTIFY);
  		if (ret < 0)
  			goto nlmsg_fail;
  	}
  
  	authtype = cifs_select_sectype(swnreg->tcon->ses->server, swnreg->tcon->ses->sectype);
  	switch (authtype) {
  	case Kerberos:
  		ret = cifs_swn_auth_info_krb(swnreg->tcon, skb);
  		if (ret < 0) {
  			cifs_dbg(VFS, "%s: Failed to get kerberos auth info: %d\n", __func__, ret);
  			goto nlmsg_fail;
  		}
  		break;
  	case NTLMv2:
  	case RawNTLMSSP:
  		ret = cifs_swn_auth_info_ntlm(swnreg->tcon, skb);
  		if (ret < 0) {
  			cifs_dbg(VFS, "%s: Failed to get NTLM auth info: %d\n", __func__, ret);
  			goto nlmsg_fail;
  		}
  		break;
  	default:
  		cifs_dbg(VFS, "%s: secType %d not supported!\n", __func__, authtype);
  		ret = -EINVAL;
  		goto nlmsg_fail;
  	}
  
  	genlmsg_end(skb, hdr);
  	genlmsg_multicast(&cifs_genl_family, skb, 0, CIFS_GENL_MCGRP_SWN, GFP_ATOMIC);
  
  	cifs_dbg(FYI, "%s: Message to register for network name %s with id %d sent\n", __func__,
  			swnreg->net_name, swnreg->id);
  
  	return 0;
  
  nlmsg_fail:
  	genlmsg_cancel(skb, hdr);
  	nlmsg_free(skb);
  fail:
  	return ret;
  }
  
  /*
   * Sends an uregister message to the userspace daemon based on the registration
   */
  static int cifs_swn_send_unregister_message(struct cifs_swn_reg *swnreg)
  {
  	struct sk_buff *skb;
  	struct genlmsghdr *hdr;
  	int ret;
  
  	skb = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
  	if (skb == NULL)
  		return -ENOMEM;
  
  	hdr = genlmsg_put(skb, 0, 0, &cifs_genl_family, 0, CIFS_GENL_CMD_SWN_UNREGISTER);
  	if (hdr == NULL) {
  		ret = -ENOMEM;
  		goto nlmsg_fail;
  	}
  
  	ret = nla_put_u32(skb, CIFS_GENL_ATTR_SWN_REGISTRATION_ID, swnreg->id);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_NET_NAME, swnreg->net_name);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME, swnreg->share_name);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage),
  			&swnreg->tcon->ses->server->dstaddr);
  	if (ret < 0)
  		goto nlmsg_fail;
  
  	if (swnreg->net_name_notify) {
  		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_NET_NAME_NOTIFY);
  		if (ret < 0)
  			goto nlmsg_fail;
  	}
  
  	if (swnreg->share_name_notify) {
  		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME_NOTIFY);
  		if (ret < 0)
  			goto nlmsg_fail;
  	}
  
  	if (swnreg->ip_notify) {
  		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_IP_NOTIFY);
  		if (ret < 0)
  			goto nlmsg_fail;
  	}
  
  	genlmsg_end(skb, hdr);
  	genlmsg_multicast(&cifs_genl_family, skb, 0, CIFS_GENL_MCGRP_SWN, GFP_ATOMIC);
  
  	cifs_dbg(FYI, "%s: Message to unregister for network name %s with id %d sent\n", __func__,
  			swnreg->net_name, swnreg->id);
  
  	return 0;
  
  nlmsg_fail:
  	genlmsg_cancel(skb, hdr);
  	nlmsg_free(skb);
  	return ret;
  }
  
  /*
   * Try to find a matching registration for the tcon's server name and share name.
   * Calls to this function must be protected by cifs_swnreg_idr_mutex.
   * TODO Try to avoid memory allocations
   */
  static struct cifs_swn_reg *cifs_find_swn_reg(struct cifs_tcon *tcon)
  {
  	struct cifs_swn_reg *swnreg;
  	int id;
  	const char *share_name;
  	const char *net_name;
  
  	net_name = extract_hostname(tcon->treeName);
  	if (IS_ERR(net_name)) {
  		int ret;
  
  		ret = PTR_ERR(net_name);
  		cifs_dbg(VFS, "%s: failed to extract host name from target '%s': %d\n",
  				__func__, tcon->treeName, ret);
  		return ERR_PTR(-EINVAL);
  	}
  
  	share_name = extract_sharename(tcon->treeName);
  	if (IS_ERR(share_name)) {
  		int ret;
  
  		ret = PTR_ERR(share_name);
  		cifs_dbg(VFS, "%s: failed to extract share name from target '%s': %d\n",
  				__func__, tcon->treeName, ret);
  		kfree(net_name);
  		return ERR_PTR(-EINVAL);
  	}
  
  	idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
  		if (strcasecmp(swnreg->net_name, net_name) != 0
  		    || strcasecmp(swnreg->share_name, share_name) != 0) {
  			continue;
  		}
  
  		cifs_dbg(FYI, "Existing swn registration for %s:%s found\n", swnreg->net_name,
  				swnreg->share_name);
  
  		kfree(net_name);
  		kfree(share_name);
  
  		return swnreg;
  	}
  
  	kfree(net_name);
  	kfree(share_name);
  
  	return ERR_PTR(-EEXIST);
  }
  
  /*
   * Get a registration for the tcon's server and share name, allocating a new one if it does not
   * exists
   */
  static struct cifs_swn_reg *cifs_get_swn_reg(struct cifs_tcon *tcon)
  {
  	struct cifs_swn_reg *reg = NULL;
  	int ret;
  
  	mutex_lock(&cifs_swnreg_idr_mutex);
  
  	/* Check if we are already registered for this network and share names */
  	reg = cifs_find_swn_reg(tcon);
  	if (!IS_ERR(reg)) {
  		kref_get(&reg->ref_count);
  		mutex_unlock(&cifs_swnreg_idr_mutex);
  		return reg;
  	} else if (PTR_ERR(reg) != -EEXIST) {
  		mutex_unlock(&cifs_swnreg_idr_mutex);
  		return reg;
  	}
  
  	reg = kmalloc(sizeof(struct cifs_swn_reg), GFP_ATOMIC);
  	if (reg == NULL) {
  		mutex_unlock(&cifs_swnreg_idr_mutex);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	kref_init(&reg->ref_count);
  
  	reg->id = idr_alloc(&cifs_swnreg_idr, reg, 1, 0, GFP_ATOMIC);
  	if (reg->id < 0) {
  		cifs_dbg(FYI, "%s: failed to allocate registration id\n", __func__);
  		ret = reg->id;
  		goto fail;
  	}
  
  	reg->net_name = extract_hostname(tcon->treeName);
  	if (IS_ERR(reg->net_name)) {
  		ret = PTR_ERR(reg->net_name);
  		cifs_dbg(VFS, "%s: failed to extract host name from target: %d\n", __func__, ret);
  		goto fail_idr;
  	}
  
  	reg->share_name = extract_sharename(tcon->treeName);
  	if (IS_ERR(reg->share_name)) {
  		ret = PTR_ERR(reg->share_name);
  		cifs_dbg(VFS, "%s: failed to extract share name from target: %d\n", __func__, ret);
  		goto fail_net_name;
  	}
  
  	reg->net_name_notify = true;
  	reg->share_name_notify = true;
  	reg->ip_notify = (tcon->capabilities & SMB2_SHARE_CAP_SCALEOUT);
  
  	reg->tcon = tcon;
  
  	mutex_unlock(&cifs_swnreg_idr_mutex);
  
  	return reg;
  
  fail_net_name:
  	kfree(reg->net_name);
  fail_idr:
  	idr_remove(&cifs_swnreg_idr, reg->id);
  fail:
  	kfree(reg);
  	mutex_unlock(&cifs_swnreg_idr_mutex);
  	return ERR_PTR(ret);
  }
  
  static void cifs_swn_reg_release(struct kref *ref)
  {
  	struct cifs_swn_reg *swnreg = container_of(ref, struct cifs_swn_reg, ref_count);
  	int ret;
  
  	ret = cifs_swn_send_unregister_message(swnreg);
  	if (ret < 0)
  		cifs_dbg(VFS, "%s: Failed to send unregister message: %d\n", __func__, ret);
  
  	idr_remove(&cifs_swnreg_idr, swnreg->id);
  	kfree(swnreg->net_name);
  	kfree(swnreg->share_name);
  	kfree(swnreg);
  }
  
  static void cifs_put_swn_reg(struct cifs_swn_reg *swnreg)
  {
  	mutex_lock(&cifs_swnreg_idr_mutex);
  	kref_put(&swnreg->ref_count, cifs_swn_reg_release);
  	mutex_unlock(&cifs_swnreg_idr_mutex);
  }
  
  static int cifs_swn_resource_state_changed(struct cifs_swn_reg *swnreg, const char *name, int state)
  {
  	switch (state) {
  	case CIFS_SWN_RESOURCE_STATE_UNAVAILABLE:
  		cifs_dbg(FYI, "%s: resource name '%s' become unavailable\n", __func__, name);
  		cifs_mark_tcp_ses_conns_for_reconnect(swnreg->tcon->ses->server, true);
  		break;
  	case CIFS_SWN_RESOURCE_STATE_AVAILABLE:
  		cifs_dbg(FYI, "%s: resource name '%s' become available\n", __func__, name);
  		cifs_mark_tcp_ses_conns_for_reconnect(swnreg->tcon->ses->server, true);
  		break;
  	case CIFS_SWN_RESOURCE_STATE_UNKNOWN:
  		cifs_dbg(FYI, "%s: resource name '%s' changed to unknown state\n", __func__, name);
  		break;
  	}
  	return 0;
  }
  
  static bool cifs_sockaddr_equal(struct sockaddr_storage *addr1, struct sockaddr_storage *addr2)
  {
  	if (addr1->ss_family != addr2->ss_family)
  		return false;
  
  	if (addr1->ss_family == AF_INET) {
  		return (memcmp(&((const struct sockaddr_in *)addr1)->sin_addr,
  				&((const struct sockaddr_in *)addr2)->sin_addr,
  				sizeof(struct in_addr)) == 0);
  	}
  
  	if (addr1->ss_family == AF_INET6) {
  		return (memcmp(&((const struct sockaddr_in6 *)addr1)->sin6_addr,
  				&((const struct sockaddr_in6 *)addr2)->sin6_addr,
  				sizeof(struct in6_addr)) == 0);
  	}
  
  	return false;
  }
  
  static int cifs_swn_store_swn_addr(const struct sockaddr_storage *new,
  				   const struct sockaddr_storage *old,
  				   struct sockaddr_storage *dst)
  {
  	__be16 port = cpu_to_be16(CIFS_PORT);
  
  	if (old->ss_family == AF_INET) {
  		struct sockaddr_in *ipv4 = (struct sockaddr_in *)old;
  
  		port = ipv4->sin_port;
  	} else if (old->ss_family == AF_INET6) {
  		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)old;
  
  		port = ipv6->sin6_port;
  	}
  
  	if (new->ss_family == AF_INET) {
  		struct sockaddr_in *ipv4 = (struct sockaddr_in *)new;
  
  		ipv4->sin_port = port;
  	} else if (new->ss_family == AF_INET6) {
  		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)new;
  
  		ipv6->sin6_port = port;
  	}
  
  	*dst = *new;
  
  	return 0;
  }
  
  static int cifs_swn_reconnect(struct cifs_tcon *tcon, struct sockaddr_storage *addr)
  {
  	int ret = 0;
  
  	/* Store the reconnect address */
  	mutex_lock(&tcon->ses->server->srv_mutex);
  	if (cifs_sockaddr_equal(&tcon->ses->server->dstaddr, addr))
  		goto unlock;
  
  	ret = cifs_swn_store_swn_addr(addr, &tcon->ses->server->dstaddr,
  				      &tcon->ses->server->swn_dstaddr);
  	if (ret < 0) {
  		cifs_dbg(VFS, "%s: failed to store address: %d\n", __func__, ret);
  		goto unlock;
  	}
  	tcon->ses->server->use_swn_dstaddr = true;
  
  	/*
  	 * Unregister to stop receiving notifications for the old IP address.
  	 */
  	ret = cifs_swn_unregister(tcon);
  	if (ret < 0) {
  		cifs_dbg(VFS, "%s: Failed to unregister for witness notifications: %d\n",
  			 __func__, ret);
  		goto unlock;
  	}
  
  	/*
  	 * And register to receive notifications for the new IP address now that we have
  	 * stored the new address.
  	 */
  	ret = cifs_swn_register(tcon);
  	if (ret < 0) {
  		cifs_dbg(VFS, "%s: Failed to register for witness notifications: %d\n",
  			 __func__, ret);
  		goto unlock;
  	}
  
  	cifs_mark_tcp_ses_conns_for_reconnect(tcon->ses->server, false);
  
  unlock:
  	mutex_unlock(&tcon->ses->server->srv_mutex);
  
  	return ret;
  }
  
  static int cifs_swn_client_move(struct cifs_swn_reg *swnreg, struct sockaddr_storage *addr)
  {
  	struct sockaddr_in *ipv4 = (struct sockaddr_in *)addr;
  	struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)addr;
  
  	if (addr->ss_family == AF_INET)
  		cifs_dbg(FYI, "%s: move to %pI4\n", __func__, &ipv4->sin_addr);
  	else if (addr->ss_family == AF_INET6)
  		cifs_dbg(FYI, "%s: move to %pI6\n", __func__, &ipv6->sin6_addr);
  
  	return cifs_swn_reconnect(swnreg->tcon, addr);
  }
  
  int cifs_swn_notify(struct sk_buff *skb, struct genl_info *info)
  {
  	struct cifs_swn_reg *swnreg;
  	char name[256];
  	int type;
  
  	if (info->attrs[CIFS_GENL_ATTR_SWN_REGISTRATION_ID]) {
  		int swnreg_id;
  
  		swnreg_id = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_REGISTRATION_ID]);
  		mutex_lock(&cifs_swnreg_idr_mutex);
  		swnreg = idr_find(&cifs_swnreg_idr, swnreg_id);
  		mutex_unlock(&cifs_swnreg_idr_mutex);
  		if (swnreg == NULL) {
  			cifs_dbg(FYI, "%s: registration id %d not found\n", __func__, swnreg_id);
  			return -EINVAL;
  		}
  	} else {
  		cifs_dbg(FYI, "%s: missing registration id attribute\n", __func__);
  		return -EINVAL;
  	}
  
  	if (info->attrs[CIFS_GENL_ATTR_SWN_NOTIFICATION_TYPE]) {
  		type = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_NOTIFICATION_TYPE]);
  	} else {
  		cifs_dbg(FYI, "%s: missing notification type attribute\n", __func__);
  		return -EINVAL;
  	}
  
  	switch (type) {
  	case CIFS_SWN_NOTIFICATION_RESOURCE_CHANGE: {
  		int state;
  
  		if (info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_NAME]) {
  			nla_strscpy(name, info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_NAME],
  					sizeof(name));
  		} else {
  			cifs_dbg(FYI, "%s: missing resource name attribute\n", __func__);
  			return -EINVAL;
  		}
  		if (info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_STATE]) {
  			state = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_STATE]);
  		} else {
  			cifs_dbg(FYI, "%s: missing resource state attribute\n", __func__);
  			return -EINVAL;
  		}
  		return cifs_swn_resource_state_changed(swnreg, name, state);
  	}
  	case CIFS_SWN_NOTIFICATION_CLIENT_MOVE: {
  		struct sockaddr_storage addr;
  
  		if (info->attrs[CIFS_GENL_ATTR_SWN_IP]) {
  			nla_memcpy(&addr, info->attrs[CIFS_GENL_ATTR_SWN_IP], sizeof(addr));
  		} else {
  			cifs_dbg(FYI, "%s: missing IP address attribute\n", __func__);
  			return -EINVAL;
  		}
  		return cifs_swn_client_move(swnreg, &addr);
  	}
  	default:
  		cifs_dbg(FYI, "%s: unknown notification type %d\n", __func__, type);
  		break;
  	}
  
  	return 0;
  }
  
  int cifs_swn_register(struct cifs_tcon *tcon)
  {
  	struct cifs_swn_reg *swnreg;
  	int ret;
  
  	swnreg = cifs_get_swn_reg(tcon);
  	if (IS_ERR(swnreg))
  		return PTR_ERR(swnreg);
  
  	ret = cifs_swn_send_register_message(swnreg);
  	if (ret < 0) {
  		cifs_dbg(VFS, "%s: Failed to send swn register message: %d\n", __func__, ret);
  		/* Do not put the swnreg or return error, the echo task will retry */
  	}
  
  	return 0;
  }
  
  int cifs_swn_unregister(struct cifs_tcon *tcon)
  {
  	struct cifs_swn_reg *swnreg;
  
  	mutex_lock(&cifs_swnreg_idr_mutex);
  
  	swnreg = cifs_find_swn_reg(tcon);
  	if (IS_ERR(swnreg)) {
  		mutex_unlock(&cifs_swnreg_idr_mutex);
  		return PTR_ERR(swnreg);
  	}
  
  	mutex_unlock(&cifs_swnreg_idr_mutex);
  
  	cifs_put_swn_reg(swnreg);
  
  	return 0;
  }
  
  void cifs_swn_dump(struct seq_file *m)
  {
  	struct cifs_swn_reg *swnreg;
  	struct sockaddr_in *sa;
  	struct sockaddr_in6 *sa6;
  	int id;
  
  	seq_puts(m, "Witness registrations:");
  
  	mutex_lock(&cifs_swnreg_idr_mutex);
  	idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
  		seq_printf(m, "\nId: %u Refs: %u Network name: '%s'%s Share name: '%s'%s Ip address: ",
  				id, kref_read(&swnreg->ref_count),
  				swnreg->net_name, swnreg->net_name_notify ? "(y)" : "(n)",
  				swnreg->share_name, swnreg->share_name_notify ? "(y)" : "(n)");
  		switch (swnreg->tcon->ses->server->dstaddr.ss_family) {
  		case AF_INET:
  			sa = (struct sockaddr_in *) &swnreg->tcon->ses->server->dstaddr;
  			seq_printf(m, "%pI4", &sa->sin_addr.s_addr);
  			break;
  		case AF_INET6:
  			sa6 = (struct sockaddr_in6 *) &swnreg->tcon->ses->server->dstaddr;
  			seq_printf(m, "%pI6", &sa6->sin6_addr.s6_addr);
  			if (sa6->sin6_scope_id)
  				seq_printf(m, "%%%u", sa6->sin6_scope_id);
  			break;
  		default:
  			seq_puts(m, "(unknown)");
  		}
  		seq_printf(m, "%s", swnreg->ip_notify ? "(y)" : "(n)");
  	}
  	mutex_unlock(&cifs_swnreg_idr_mutex);
  	seq_puts(m, "\n");
  }
  
  void cifs_swn_check(void)
  {
  	struct cifs_swn_reg *swnreg;
  	int id;
  	int ret;
  
  	mutex_lock(&cifs_swnreg_idr_mutex);
  	idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
  		ret = cifs_swn_send_register_message(swnreg);
  		if (ret < 0)
  			cifs_dbg(FYI, "%s: Failed to send register message: %d\n", __func__, ret);
  	}
  	mutex_unlock(&cifs_swnreg_idr_mutex);
  }
  