wimax: generic device management (registration, deregistration, lookup)

Implements the basic life cycles of a 'struct wimax_dev', some common
generic netlink functionality for marshalling calls to user space,
and the device state machine.

For looking up net devices based on their generic netlink family IDs,
use a low overhead method that optimizes for the case where most
systems have a single WiMAX device, or at most, a very low number of
WiMAX adaptors.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 599 insertions, 0 deletions

diff --git a/net/wimax/stack.c b/net/wimax/stack.c
new file mode 100644
index 000000000000..d4da92f8981a
--- /dev/null
+++ b/net/wimax/stack.c
@@ -0,0 +1,599 @@
+/*
+ * Linux WiMAX
+ * Initialization, addition and removal of wimax devices
+ *
+ *
+ * Copyright (C) 2005-2006 Intel Corporation <linux-wimax@intel.com>
+ * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ *
+ * This implements:
+ *
+ *   - basic life cycle of 'struct wimax_dev' [wimax_dev_*()]; on
+ *     addition/registration initialize all subfields and allocate
+ *     generic netlink resources for user space communication. On
+ *     removal/unregistration, undo all that.
+ *
+ *   - device state machine [wimax_state_change()] and support to send
+ *     reports to user space when the state changes
+ *     [wimax_gnl_re_state_change*()].
+ *
+ * See include/net/wimax.h for rationales and design.
+ *
+ * ROADMAP
+ *
+ * [__]wimax_state_change()     Called by drivers to update device's state
+ *   wimax_gnl_re_state_change_alloc()
+ *   wimax_gnl_re_state_change_send()
+ *
+ * wimax_dev_init()	        Init a device
+ * wimax_dev_add()              Register
+ *   wimax_rfkill_add()
+ *   wimax_gnl_add()            Register all the generic netlink resources.
+ *   wimax_id_table_add()
+ * wimax_dev_rm()               Unregister
+ *   wimax_id_table_rm()
+ *   wimax_gnl_rm()
+ *   wimax_rfkill_rm()
+ */
+#include <linux/device.h>
+#include <net/genetlink.h>
+#include <linux/netdevice.h>
+#include <linux/wimax.h>
+#include "wimax-internal.h"
+
+
+#define D_SUBMODULE stack
+#include "debug-levels.h"
+
+/*
+ * Authoritative source for the RE_STATE_CHANGE attribute policy
+ *
+ * We don't really use it here, but /me likes to keep the definition
+ * close to where the data is generated.
+ */
+/*
+static const
+struct nla_policy wimax_gnl_re_status_change[WIMAX_GNL_ATTR_MAX + 1] = {
+	[WIMAX_GNL_STCH_STATE_OLD] = { .type = NLA_U8 },
+	[WIMAX_GNL_STCH_STATE_NEW] = { .type = NLA_U8 },
+};
+*/
+
+
+/*
+ * Allocate a Report State Change message
+ *
+ * @header: save it, you need it for _send()
+ *
+ * Creates and fills a basic state change message; different code
+ * paths can then add more attributes to the message as needed.
+ *
+ * Use wimax_gnl_re_state_change_send() to send the returned skb.
+ *
+ * Returns: skb with the genl message if ok, IS_ERR() ptr on error
+ *     with an errno code.
+ */
+static
+struct sk_buff *wimax_gnl_re_state_change_alloc(
+	struct wimax_dev *wimax_dev,
+	enum wimax_st new_state, enum wimax_st old_state,
+	void **header)
+{
+	int result;
+	struct device *dev = wimax_dev_to_dev(wimax_dev);
+	void *data;
+	struct sk_buff *report_skb;
+
+	d_fnstart(3, dev, "(wimax_dev %p new_state %u old_state %u)\n",
+		  wimax_dev, new_state, old_state);
+	result = -ENOMEM;
+	report_skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (report_skb == NULL) {
+		dev_err(dev, "RE_STCH: can't create message\n");
+		goto error_new;
+	}
+	data = genlmsg_put(report_skb, 0, wimax_gnl_mcg.id, &wimax_gnl_family,
+			   0, WIMAX_GNL_RE_STATE_CHANGE);
+	if (data == NULL) {
+		dev_err(dev, "RE_STCH: can't put data into message\n");
+		goto error_put;
+	}
+	*header = data;
+
+	result = nla_put_u8(report_skb, WIMAX_GNL_STCH_STATE_OLD, old_state);
+	if (result < 0) {
+		dev_err(dev, "RE_STCH: Error adding OLD attr: %d\n", result);
+		goto error_put;
+	}
+	result = nla_put_u8(report_skb, WIMAX_GNL_STCH_STATE_NEW, new_state);
+	if (result < 0) {
+		dev_err(dev, "RE_STCH: Error adding NEW attr: %d\n", result);
+		goto error_put;
+	}
+	result = nla_put_u32(report_skb, WIMAX_GNL_STCH_IFIDX,
+			     wimax_dev->net_dev->ifindex);
+	if (result < 0) {
+		dev_err(dev, "RE_STCH: Error adding IFINDEX attribute\n");
+		goto error_put;
+	}
+	d_fnend(3, dev, "(wimax_dev %p new_state %u old_state %u) = %p\n",
+		wimax_dev, new_state, old_state, report_skb);
+	return report_skb;
+
+error_put:
+	nlmsg_free(report_skb);
+error_new:
+	d_fnend(3, dev, "(wimax_dev %p new_state %u old_state %u) = %d\n",
+		wimax_dev, new_state, old_state, result);
+	return ERR_PTR(result);
+}
+
+
+/*
+ * Send a Report State Change message (as created with _alloc).
+ *
+ * @report_skb: as returned by wimax_gnl_re_state_change_alloc()
+ * @header: as returned by wimax_gnl_re_state_change_alloc()
+ *
+ * Returns: 0 if ok, < 0 errno code on error.
+ *
+ * If the message is  NULL, pretend it didn't happen.
+ */
+static
+int wimax_gnl_re_state_change_send(
+	struct wimax_dev *wimax_dev, struct sk_buff *report_skb,
+	void *header)
+{
+	int result = 0;
+	struct device *dev = wimax_dev_to_dev(wimax_dev);
+	d_fnstart(3, dev, "(wimax_dev %p report_skb %p)\n",
+		  wimax_dev, report_skb);
+	if (report_skb == NULL)
+		goto out;
+	genlmsg_end(report_skb, header);
+	result = genlmsg_multicast(report_skb, 0, wimax_gnl_mcg.id, GFP_KERNEL);
+	if (result == -ESRCH)	/* Nobody connected, ignore it */
+		result = 0;	/* btw, the skb is freed already */
+	if (result < 0) {
+		dev_err(dev, "RE_STCH: Error sending: %d\n", result);
+		nlmsg_free(report_skb);
+	}
+out:
+	d_fnend(3, dev, "(wimax_dev %p report_skb %p) = %d\n",
+		wimax_dev, report_skb, result);
+	return result;
+}
+
+
+static
+void __check_new_state(enum wimax_st old_state, enum wimax_st new_state,
+		       unsigned allowed_states_bm)
+{
+	if (WARN_ON(((1 << new_state) & allowed_states_bm) == 0)) {
+		printk(KERN_ERR "SW BUG! Forbidden state change %u -> %u\n",
+			old_state, new_state);
+	}
+}
+
+
+/*
+ * Set the current state of a WiMAX device [unlocking version of
+ * wimax_state_change().
+ */
+void __wimax_state_change(struct wimax_dev *wimax_dev, enum wimax_st new_state)
+{
+	struct device *dev = wimax_dev_to_dev(wimax_dev);
+	enum wimax_st old_state = wimax_dev->state;
+	struct sk_buff *stch_skb;
+	void *header;
+
+	d_fnstart(3, dev, "(wimax_dev %p new_state %u [old %u])\n",
+		  wimax_dev, new_state, old_state);
+
+	if (WARN_ON(new_state >= __WIMAX_ST_INVALID)) {
+		dev_err(dev, "SW BUG: requesting invalid state %u\n",
+			new_state);
+		goto out;
+	}
+	if (old_state == new_state)
+		goto out;
+	header = NULL;	/* gcc complains? can't grok why */
+	stch_skb = wimax_gnl_re_state_change_alloc(
+		wimax_dev, new_state, old_state, &header);
+
+	/* Verify the state transition and do exit-from-state actions */
+	switch (old_state) {
+	case __WIMAX_ST_NULL:
+		__check_new_state(old_state, new_state,
+				  1 << WIMAX_ST_DOWN);
+		break;
+	case WIMAX_ST_DOWN:
+		__check_new_state(old_state, new_state,
+				  1 << __WIMAX_ST_QUIESCING
+				  | 1 << WIMAX_ST_UNINITIALIZED
+				  | 1 << WIMAX_ST_RADIO_OFF);
+		break;
+	case __WIMAX_ST_QUIESCING:
+		__check_new_state(old_state, new_state, 1 << WIMAX_ST_DOWN);
+		break;
+	case WIMAX_ST_UNINITIALIZED:
+		__check_new_state(old_state, new_state,
+				  1 << __WIMAX_ST_QUIESCING
+				  | 1 << WIMAX_ST_RADIO_OFF);
+		break;
+	case WIMAX_ST_RADIO_OFF:
+		__check_new_state(old_state, new_state,
+				  1 << __WIMAX_ST_QUIESCING
+				  | 1 << WIMAX_ST_READY);
+		break;
+	case WIMAX_ST_READY:
+		__check_new_state(old_state, new_state,
+				  1 << __WIMAX_ST_QUIESCING
+				  | 1 << WIMAX_ST_RADIO_OFF
+				  | 1 << WIMAX_ST_SCANNING
+				  | 1 << WIMAX_ST_CONNECTING
+				  | 1 << WIMAX_ST_CONNECTED);
+		break;
+	case WIMAX_ST_SCANNING:
+		__check_new_state(old_state, new_state,
+				  1 << __WIMAX_ST_QUIESCING
+				  | 1 << WIMAX_ST_RADIO_OFF
+				  | 1 << WIMAX_ST_READY
+				  | 1 << WIMAX_ST_CONNECTING
+				  | 1 << WIMAX_ST_CONNECTED);
+		break;
+	case WIMAX_ST_CONNECTING:
+		__check_new_state(old_state, new_state,
+				  1 << __WIMAX_ST_QUIESCING
+				  | 1 << WIMAX_ST_RADIO_OFF
+				  | 1 << WIMAX_ST_READY
+				  | 1 << WIMAX_ST_SCANNING
+				  | 1 << WIMAX_ST_CONNECTED);
+		break;
+	case WIMAX_ST_CONNECTED:
+		__check_new_state(old_state, new_state,
+				  1 << __WIMAX_ST_QUIESCING
+				  | 1 << WIMAX_ST_RADIO_OFF
+				  | 1 << WIMAX_ST_READY);
+		netif_tx_disable(wimax_dev->net_dev);
+		netif_carrier_off(wimax_dev->net_dev);
+		break;
+	case __WIMAX_ST_INVALID:
+	default:
+		dev_err(dev, "SW BUG: wimax_dev %p is in unknown state %u\n",
+			wimax_dev, wimax_dev->state);
+		WARN_ON(1);
+		goto out;
+	}
+
+	/* Execute the actions of entry to the new state */
+	switch (new_state) {
+	case __WIMAX_ST_NULL:
+		dev_err(dev, "SW BUG: wimax_dev %p entering NULL state "
+			"from %u\n", wimax_dev, wimax_dev->state);
+		WARN_ON(1);		/* Nobody can enter this state */
+		break;
+	case WIMAX_ST_DOWN:
+		break;
+	case __WIMAX_ST_QUIESCING:
+		break;
+	case WIMAX_ST_UNINITIALIZED:
+		break;
+	case WIMAX_ST_RADIO_OFF:
+		break;
+	case WIMAX_ST_READY:
+		break;
+	case WIMAX_ST_SCANNING:
+		break;
+	case WIMAX_ST_CONNECTING:
+		break;
+	case WIMAX_ST_CONNECTED:
+		netif_carrier_on(wimax_dev->net_dev);
+		netif_wake_queue(wimax_dev->net_dev);
+		break;
+	case __WIMAX_ST_INVALID:
+	default:
+		BUG();
+	}
+	__wimax_state_set(wimax_dev, new_state);
+	if (stch_skb)
+		wimax_gnl_re_state_change_send(wimax_dev, stch_skb, header);
+out:
+	d_fnend(3, dev, "(wimax_dev %p new_state %u [old %u]) = void\n",
+		wimax_dev, new_state, old_state);
+	return;
+}
+
+
+/**
+ * wimax_state_change - Set the current state of a WiMAX device
+ *
+ * @wimax_dev: WiMAX device descriptor (properly referenced)
+ * @new_state: New state to switch to
+ *
+ * This implements the state changes for the wimax devices. It will
+ *
+ * - verify that the state transition is legal (for now it'll just
+ *   print a warning if not) according to the table in
+ *   linux/wimax.h's documentation for 'enum wimax_st'.
+ *
+ * - perform the actions needed for leaving the current state and
+ *   whichever are needed for entering the new state.
+ *
+ * - issue a report to user space indicating the new state (and an
+ *   optional payload with information about the new state).
+ *
+ * NOTE: @wimax_dev must be locked
+ */
+void wimax_state_change(struct wimax_dev *wimax_dev, enum wimax_st new_state)
+{
+	mutex_lock(&wimax_dev->mutex);
+	__wimax_state_change(wimax_dev, new_state);
+	mutex_unlock(&wimax_dev->mutex);
+	return;
+}
+EXPORT_SYMBOL_GPL(wimax_state_change);
+
+
+/**
+ * wimax_state_get() - Return the current state of a WiMAX device
+ *
+ * @wimax_dev: WiMAX device descriptor
+ *
+ * Returns: Current state of the device according to its driver.
+ */
+enum wimax_st wimax_state_get(struct wimax_dev *wimax_dev)
+{
+	enum wimax_st state;
+	mutex_lock(&wimax_dev->mutex);
+	state = wimax_dev->state;
+	mutex_unlock(&wimax_dev->mutex);
+	return state;
+}
+EXPORT_SYMBOL_GPL(wimax_state_get);
+
+
+/**
+ * wimax_dev_init - initialize a newly allocated instance
+ *
+ * @wimax_dev: WiMAX device descriptor to initialize.
+ *
+ * Initializes fields of a freshly allocated @wimax_dev instance. This
+ * function assumes that after allocation, the memory occupied by
+ * @wimax_dev was zeroed.
+ */
+void wimax_dev_init(struct wimax_dev *wimax_dev)
+{
+	INIT_LIST_HEAD(&wimax_dev->id_table_node);
+	__wimax_state_set(wimax_dev, WIMAX_ST_UNINITIALIZED);
+	mutex_init(&wimax_dev->mutex);
+	mutex_init(&wimax_dev->mutex_reset);
+}
+EXPORT_SYMBOL_GPL(wimax_dev_init);
+
+/*
+ * This extern is declared here because it's easier to keep track --
+ * both declarations are a list of the same
+ */
+extern struct genl_ops
+	wimax_gnl_msg_from_user,
+	wimax_gnl_reset,
+	wimax_gnl_rfkill;
+
+static
+struct genl_ops *wimax_gnl_ops[] = {
+	&wimax_gnl_msg_from_user,
+	&wimax_gnl_reset,
+	&wimax_gnl_rfkill,
+};
+
+
+static
+size_t wimax_addr_scnprint(char *addr_str, size_t addr_str_size,
+			   unsigned char *addr, size_t addr_len)
+{
+	unsigned cnt, total;
+	for (total = cnt = 0; cnt < addr_len; cnt++)
+		total += scnprintf(addr_str + total, addr_str_size - total,
+				   "%02x%c", addr[cnt],
+				   cnt == addr_len - 1 ? '\0' : ':');
+	return total;
+}
+
+
+/**
+ * wimax_dev_add - Register a new WiMAX device
+ *
+ * @wimax_dev: WiMAX device descriptor (as embedded in your @net_dev's
+ *     priv data). You must have called wimax_dev_init() on it before.
+ *
+ * @net_dev: net device the @wimax_dev is associated with. The
+ *     function expects SET_NETDEV_DEV() and register_netdev() were
+ *     already called on it.
+ *
+ * Registers the new WiMAX device, sets up the user-kernel control
+ * interface (generic netlink) and common WiMAX infrastructure.
+ *
+ * Note that the parts that will allow interaction with user space are
+ * setup at the very end, when the rest is in place, as once that
+ * happens, the driver might get user space control requests via
+ * netlink or from debugfs that might translate into calls into
+ * wimax_dev->op_*().
+ */
+int wimax_dev_add(struct wimax_dev *wimax_dev, struct net_device *net_dev)
+{
+	int result;
+	struct device *dev = net_dev->dev.parent;
+	char addr_str[32];
+
+	d_fnstart(3, dev, "(wimax_dev %p net_dev %p)\n", wimax_dev, net_dev);
+
+	/* Do the RFKILL setup before locking, as RFKILL will call
+	 * into our functions. */
+	wimax_dev->net_dev = net_dev;
+	result = wimax_rfkill_add(wimax_dev);
+	if (result < 0)
+		goto error_rfkill_add;
+
+	/* Set up user-space interaction */
+	mutex_lock(&wimax_dev->mutex);
+	wimax_id_table_add(wimax_dev);
+	result = wimax_debugfs_add(wimax_dev);
+	if (result < 0) {
+		dev_err(dev, "cannot initialize debugfs: %d\n",
+			result);
+		goto error_debugfs_add;
+	}
+
+	__wimax_state_set(wimax_dev, WIMAX_ST_DOWN);
+	mutex_unlock(&wimax_dev->mutex);
+
+	wimax_addr_scnprint(addr_str, sizeof(addr_str),
+			    net_dev->dev_addr, net_dev->addr_len);
+	dev_err(dev, "WiMAX interface %s (%s) ready\n",
+		net_dev->name, addr_str);
+	d_fnend(3, dev, "(wimax_dev %p net_dev %p) = 0\n", wimax_dev, net_dev);
+	return 0;
+
+error_debugfs_add:
+	wimax_id_table_rm(wimax_dev);
+	mutex_unlock(&wimax_dev->mutex);
+	wimax_rfkill_rm(wimax_dev);
+error_rfkill_add:
+	d_fnend(3, dev, "(wimax_dev %p net_dev %p) = %d\n",
+		wimax_dev, net_dev, result);
+	return result;
+}
+EXPORT_SYMBOL_GPL(wimax_dev_add);
+
+
+/**
+ * wimax_dev_rm - Unregister an existing WiMAX device
+ *
+ * @wimax_dev: WiMAX device descriptor
+ *
+ * Unregisters a WiMAX device previously registered for use with
+ * wimax_add_rm().
+ *
+ * IMPORTANT! Must call before calling unregister_netdev().
+ *
+ * After this function returns, you will not get any more user space
+ * control requests (via netlink or debugfs) and thus to wimax_dev->ops.
+ *
+ * Reentrancy control is ensured by setting the state to
+ * %__WIMAX_ST_QUIESCING. rfkill operations coming through
+ * wimax_*rfkill*() will be stopped by the quiescing state; ops coming
+ * from the rfkill subsystem will be stopped by the support being
+ * removed by wimax_rfkill_rm().
+ */
+void wimax_dev_rm(struct wimax_dev *wimax_dev)
+{
+	d_fnstart(3, NULL, "(wimax_dev %p)\n", wimax_dev);
+
+	mutex_lock(&wimax_dev->mutex);
+	__wimax_state_change(wimax_dev, __WIMAX_ST_QUIESCING);
+	wimax_debugfs_rm(wimax_dev);
+	wimax_id_table_rm(wimax_dev);
+	__wimax_state_change(wimax_dev, WIMAX_ST_DOWN);
+	mutex_unlock(&wimax_dev->mutex);
+	wimax_rfkill_rm(wimax_dev);
+	d_fnend(3, NULL, "(wimax_dev %p) = void\n", wimax_dev);
+}
+EXPORT_SYMBOL_GPL(wimax_dev_rm);
+
+struct genl_family wimax_gnl_family = {
+	.id = GENL_ID_GENERATE,
+	.name = "WiMAX",
+	.version = WIMAX_GNL_VERSION,
+	.hdrsize = 0,
+	.maxattr = WIMAX_GNL_ATTR_MAX,
+};
+
+struct genl_multicast_group wimax_gnl_mcg = {
+	.name = "msg",
+};
+
+
+
+/* Shutdown the wimax stack */
+static
+int __init wimax_subsys_init(void)
+{
+	int result, cnt;
+
+	d_fnstart(4, NULL, "()\n");
+	snprintf(wimax_gnl_family.name, sizeof(wimax_gnl_family.name),
+		 "WiMAX");
+	result = genl_register_family(&wimax_gnl_family);
+	if (unlikely(result < 0)) {
+		printk(KERN_ERR "cannot register generic netlink family: %d\n",
+		       result);
+		goto error_register_family;
+	}
+
+	for (cnt = 0; cnt < ARRAY_SIZE(wimax_gnl_ops); cnt++) {
+		result = genl_register_ops(&wimax_gnl_family,
+					   wimax_gnl_ops[cnt]);
+		d_printf(4, NULL, "registering generic netlink op code "
+			 "%u: %d\n", wimax_gnl_ops[cnt]->cmd, result);
+		if (unlikely(result < 0)) {
+			printk(KERN_ERR "cannot register generic netlink op "
+			       "code %u: %d\n",
+			       wimax_gnl_ops[cnt]->cmd, result);
+			goto error_register_ops;
+		}
+	}
+
+	result = genl_register_mc_group(&wimax_gnl_family, &wimax_gnl_mcg);
+	if (result < 0)
+		goto error_mc_group;
+	d_fnend(4, NULL, "() = 0\n");
+	return 0;
+
+error_mc_group:
+error_register_ops:
+	for (cnt--; cnt >= 0; cnt--)
+		genl_unregister_ops(&wimax_gnl_family,
+				    wimax_gnl_ops[cnt]);
+	genl_unregister_family(&wimax_gnl_family);
+error_register_family:
+	d_fnend(4, NULL, "() = %d\n", result);
+	return result;
+
+}
+module_init(wimax_subsys_init);
+
+
+/* Shutdown the wimax stack */
+static
+void __exit wimax_subsys_exit(void)
+{
+	int cnt;
+	wimax_id_table_release();
+	genl_unregister_mc_group(&wimax_gnl_family, &wimax_gnl_mcg);
+	for (cnt = ARRAY_SIZE(wimax_gnl_ops) - 1; cnt >= 0; cnt--)
+		genl_unregister_ops(&wimax_gnl_family,
+				    wimax_gnl_ops[cnt]);
+	genl_unregister_family(&wimax_gnl_family);
+}
+module_exit(wimax_subsys_exit);
+
+MODULE_AUTHOR("Intel Corporation <linux-wimax@intel.com>");
+MODULE_DESCRIPTION("Linux WiMAX stack");
+MODULE_LICENSE("GPL");
+