net/ncsi: Resource management

NCSI spec (DSP0222) defines several objects: package, channel, mode,
filter, version and statistics etc. This introduces the data structs
to represent those objects and implement functions to manage them.
Also, this introduces CONFIG_NET_NCSI for the newly implemented NCSI
stack.

   * The user (e.g. netdev driver) dereference NCSI device by
     "struct ncsi_dev", which is embedded to "struct ncsi_dev_priv".
     The later one is used by NCSI stack internally.
   * Every NCSI device can have multiple packages simultaneously, up
     to 8 packages. It's represented by "struct ncsi_package" and
     identified by 3-bits ID.
   * Every NCSI package can have multiple channels, up to 32. It's
     represented by "struct ncsi_channel" and identified by 5-bits ID.
   * Every NCSI channel has version, statistics, various modes and
     filters. They are represented by "struct ncsi_channel_version",
     "struct ncsi_channel_stats", "struct ncsi_channel_mode" and
     "struct ncsi_channel_filter" separately.
   * Apart from AEN (Asynchronous Event Notification), the NCSI stack
     works in terms of command and response. This introduces "struct
     ncsi_req" to represent a complete NCSI transaction made of NCSI
     request and response.

link: https://www.dmtf.org/sites/default/files/standards/documents/DSP0222_1.1.0.pdfSigned-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ncsi.h

+#ifndef __NET_NCSI_H
+#define __NET_NCSI_H
+
+/*
+ * The NCSI device states seen from external. More NCSI device states are
+ * only visible internally (in net/ncsi/internal.h). When the NCSI device
+ * is registered, it's in ncsi_dev_state_registered state. The state
+ * ncsi_dev_state_start is used to drive to choose active package and
+ * channel. After that, its state is changed to ncsi_dev_state_functional.
+ *
+ * The state ncsi_dev_state_stop helps to shut down the currently active
+ * package and channel while ncsi_dev_state_config helps to reconfigure
+ * them.
+ */
+enum {
+	ncsi_dev_state_registered	= 0x0000,
+	ncsi_dev_state_functional	= 0x0100,
+	ncsi_dev_state_probe		= 0x0200,
+	ncsi_dev_state_config		= 0x0300,
+	ncsi_dev_state_suspend		= 0x0400,
+};
+
+struct ncsi_dev {
+	int               state;
+	int		  link_up;
+	struct net_device *dev;
+	void		  (*handler)(struct ncsi_dev *ndev);
+};
+
+#ifdef CONFIG_NET_NCSI
+struct ncsi_dev *ncsi_register_dev(struct net_device *dev,
+				   void (*notifier)(struct ncsi_dev *nd));
+void ncsi_unregister_dev(struct ncsi_dev *nd);
+#else /* !CONFIG_NET_NCSI */
+static inline struct ncsi_dev *ncsi_register_dev(struct net_device *dev,
+					void (*notifier)(struct ncsi_dev *nd))
+{
+	return NULL;
+}
+
+static inline void ncsi_unregister_dev(struct ncsi_dev *nd)
+{
+}
+#endif /* CONFIG_NET_NCSI */
+
+#endif /* __NET_NCSI_H */

net/Kconfig

@@ -237,6 +237,7 @@ source "net/hsr/Kconfig"
 source "net/switchdev/Kconfig"
 source "net/l3mdev/Kconfig"
 source "net/qrtr/Kconfig"
+source "net/ncsi/Kconfig"
 
 config RPS
 	bool

net/Makefile

@@ -79,3 +79,4 @@ ifneq ($(CONFIG_NET_L3_MASTER_DEV),)
 obj-y				+= l3mdev/
 endif
 obj-$(CONFIG_QRTR)		+= qrtr/
+obj-$(CONFIG_NET_NCSI)		+= ncsi/

net/ncsi/Kconfig

+#
+# Configuration for NCSI support
+#
+
+config NET_NCSI
+	bool "NCSI interface support"
+	depends on INET
+	---help---
+	  This module provides NCSI (Network Controller Sideband Interface)
+	  support. Enable this only if your system connects to a network
+	  device via NCSI and the ethernet driver you're using supports
+	  the protocol explicitly.

net/ncsi/Makefile

+#
+# Makefile for NCSI API
+#
+obj-$(CONFIG_NET_NCSI) += ncsi-manage.o

net/ncsi/ncsi-manage.c

+/*
+ * Copyright Gavin Shan, IBM Corporation 2016.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+
+#include <net/ncsi.h>
+#include <net/net_namespace.h>
+#include <net/sock.h>
+
+#include "internal.h"
+
+LIST_HEAD(ncsi_dev_list);
+DEFINE_SPINLOCK(ncsi_dev_lock);
+
+static inline int ncsi_filter_size(int table)
+{
+	int sizes[] = { 2, 6, 6, 6 };
+
+	BUILD_BUG_ON(ARRAY_SIZE(sizes) != NCSI_FILTER_MAX);
+	if (table < NCSI_FILTER_BASE || table >= NCSI_FILTER_MAX)
+		return -EINVAL;
+
+	return sizes[table];
+}
+
+int ncsi_find_filter(struct ncsi_channel *nc, int table, void *data)
+{
+	struct ncsi_channel_filter *ncf;
+	void *bitmap;
+	int index, size;
+	unsigned long flags;
+
+	ncf = nc->filters[table];
+	if (!ncf)
+		return -ENXIO;
+
+	size = ncsi_filter_size(table);
+	if (size < 0)
+		return size;
+
+	spin_lock_irqsave(&nc->lock, flags);
+	bitmap = (void *)&ncf->bitmap;
+	index = -1;
+	while ((index = find_next_bit(bitmap, ncf->total, index + 1))
+	       < ncf->total) {
+		if (!memcmp(ncf->data + size * index, data, size)) {
+			spin_unlock_irqrestore(&nc->lock, flags);
+			return index;
+		}
+	}
+	spin_unlock_irqrestore(&nc->lock, flags);
+
+	return -ENOENT;
+}
+
+int ncsi_add_filter(struct ncsi_channel *nc, int table, void *data)
+{
+	struct ncsi_channel_filter *ncf;
+	int index, size;
+	void *bitmap;
+	unsigned long flags;
+
+	size = ncsi_filter_size(table);
+	if (size < 0)
+		return size;
+
+	index = ncsi_find_filter(nc, table, data);
+	if (index >= 0)
+		return index;
+
+	ncf = nc->filters[table];
+	if (!ncf)
+		return -ENODEV;
+
+	spin_lock_irqsave(&nc->lock, flags);
+	bitmap = (void *)&ncf->bitmap;
+	do {
+		index = find_next_zero_bit(bitmap, ncf->total, 0);
+		if (index >= ncf->total) {
+			spin_unlock_irqrestore(&nc->lock, flags);
+			return -ENOSPC;
+		}
+	} while (test_and_set_bit(index, bitmap));
+
+	memcpy(ncf->data + size * index, data, size);
+	spin_unlock_irqrestore(&nc->lock, flags);
+
+	return index;
+}
+
+int ncsi_remove_filter(struct ncsi_channel *nc, int table, int index)
+{
+	struct ncsi_channel_filter *ncf;
+	int size;
+	void *bitmap;
+	unsigned long flags;
+
+	size = ncsi_filter_size(table);
+	if (size < 0)
+		return size;
+
+	ncf = nc->filters[table];
+	if (!ncf || index >= ncf->total)
+		return -ENODEV;
+
+	spin_lock_irqsave(&nc->lock, flags);
+	bitmap = (void *)&ncf->bitmap;
+	if (test_and_clear_bit(index, bitmap))
+		memset(ncf->data + size * index, 0, size);
+	spin_unlock_irqrestore(&nc->lock, flags);
+
+	return 0;
+}
+
+struct ncsi_channel *ncsi_find_channel(struct ncsi_package *np,
+				       unsigned char id)
+{
+	struct ncsi_channel *nc;
+
+	NCSI_FOR_EACH_CHANNEL(np, nc) {
+		if (nc->id == id)
+			return nc;
+	}
+
+	return NULL;
+}
+
+struct ncsi_channel *ncsi_add_channel(struct ncsi_package *np, unsigned char id)
+{
+	struct ncsi_channel *nc, *tmp;
+	int index;
+	unsigned long flags;
+
+	nc = kzalloc(sizeof(*nc), GFP_ATOMIC);
+	if (!nc)
+		return NULL;
+
+	nc->id = id;
+	nc->package = np;
+	nc->state = NCSI_CHANNEL_INACTIVE;
+	spin_lock_init(&nc->lock);
+	for (index = 0; index < NCSI_CAP_MAX; index++)
+		nc->caps[index].index = index;
+	for (index = 0; index < NCSI_MODE_MAX; index++)
+		nc->modes[index].index = index;
+
+	spin_lock_irqsave(&np->lock, flags);
+	tmp = ncsi_find_channel(np, id);
+	if (tmp) {
+		spin_unlock_irqrestore(&np->lock, flags);
+		kfree(nc);
+		return tmp;
+	}
+
+	list_add_tail_rcu(&nc->node, &np->channels);
+	np->channel_num++;
+	spin_unlock_irqrestore(&np->lock, flags);
+
+	return nc;
+}
+
+static void ncsi_remove_channel(struct ncsi_channel *nc)
+{
+	struct ncsi_package *np = nc->package;
+	struct ncsi_channel_filter *ncf;
+	unsigned long flags;
+	int i;
+
+	/* Release filters */
+	spin_lock_irqsave(&nc->lock, flags);
+	for (i = 0; i < NCSI_FILTER_MAX; i++) {
+		ncf = nc->filters[i];
+		if (!ncf)
+			continue;
+
+		nc->filters[i] = NULL;
+		kfree(ncf);
+	}
+
+	nc->state = NCSI_CHANNEL_INACTIVE;
+	spin_unlock_irqrestore(&nc->lock, flags);
+
+	/* Remove and free channel */
+	spin_lock_irqsave(&np->lock, flags);
+	list_del_rcu(&nc->node);
+	np->channel_num--;
+	spin_unlock_irqrestore(&np->lock, flags);
+
+	kfree(nc);
+}
+
+struct ncsi_package *ncsi_find_package(struct ncsi_dev_priv *ndp,
+				       unsigned char id)
+{
+	struct ncsi_package *np;
+
+	NCSI_FOR_EACH_PACKAGE(ndp, np) {
+		if (np->id == id)
+			return np;
+	}
+
+	return NULL;
+}
+
+struct ncsi_package *ncsi_add_package(struct ncsi_dev_priv *ndp,
+				      unsigned char id)
+{
+	struct ncsi_package *np, *tmp;
+	unsigned long flags;
+
+	np = kzalloc(sizeof(*np), GFP_ATOMIC);
+	if (!np)
+		return NULL;
+
+	np->id = id;
+	np->ndp = ndp;
+	spin_lock_init(&np->lock);
+	INIT_LIST_HEAD(&np->channels);
+
+	spin_lock_irqsave(&ndp->lock, flags);
+	tmp = ncsi_find_package(ndp, id);
+	if (tmp) {
+		spin_unlock_irqrestore(&ndp->lock, flags);
+		kfree(np);
+		return tmp;
+	}
+
+	list_add_tail_rcu(&np->node, &ndp->packages);
+	ndp->package_num++;
+	spin_unlock_irqrestore(&ndp->lock, flags);
+
+	return np;
+}
+
+void ncsi_remove_package(struct ncsi_package *np)
+{
+	struct ncsi_dev_priv *ndp = np->ndp;
+	struct ncsi_channel *nc, *tmp;
+	unsigned long flags;
+
+	/* Release all child channels */
+	list_for_each_entry_safe(nc, tmp, &np->channels, node)
+		ncsi_remove_channel(nc);
+
+	/* Remove and free package */
+	spin_lock_irqsave(&ndp->lock, flags);
+	list_del_rcu(&np->node);
+	ndp->package_num--;
+	spin_unlock_irqrestore(&ndp->lock, flags);
+
+	kfree(np);
+}
+
+void ncsi_find_package_and_channel(struct ncsi_dev_priv *ndp,
+				   unsigned char id,
+				   struct ncsi_package **np,
+				   struct ncsi_channel **nc)
+{
+	struct ncsi_package *p;
+	struct ncsi_channel *c;
+
+	p = ncsi_find_package(ndp, NCSI_PACKAGE_INDEX(id));
+	c = p ? ncsi_find_channel(p, NCSI_CHANNEL_INDEX(id)) : NULL;
+
+	if (np)
+		*np = p;
+	if (nc)
+		*nc = c;
+}
+
+/* For two consecutive NCSI commands, the packet IDs shouldn't
+ * be same. Otherwise, the bogus response might be replied. So
+ * the available IDs are allocated in round-robin fashion.
+ */
+struct ncsi_request *ncsi_alloc_request(struct ncsi_dev_priv *ndp, bool driven)
+{
+	struct ncsi_request *nr = NULL;
+	int i, limit = ARRAY_SIZE(ndp->requests);
+	unsigned long flags;
+
+	/* Check if there is one available request until the ceiling */
+	spin_lock_irqsave(&ndp->lock, flags);
+	for (i = ndp->request_id; !nr && i < limit; i++) {
+		if (ndp->requests[i].used)
+			continue;
+
+		nr = &ndp->requests[i];
+		nr->used = true;
+		nr->driven = driven;
+		if (++ndp->request_id >= limit)
+			ndp->request_id = 0;
+	}
+
+	/* Fail back to check from the starting cursor */
+	for (i = 0; !nr && i < ndp->request_id; i++) {
+		if (ndp->requests[i].used)
+			continue;
+
+		nr = &ndp->requests[i];
+		nr->used = true;
+		nr->driven = driven;
+		if (++ndp->request_id >= limit)
+			ndp->request_id = 0;
+	}
+	spin_unlock_irqrestore(&ndp->lock, flags);
+
+	return nr;
+}
+
+void ncsi_free_request(struct ncsi_request *nr)
+{
+	struct ncsi_dev_priv *ndp = nr->ndp;
+	struct sk_buff *cmd, *rsp;
+	unsigned long flags;
+
+	if (nr->enabled) {
+		nr->enabled = false;
+		del_timer_sync(&nr->timer);
+	}
+
+	spin_lock_irqsave(&ndp->lock, flags);
+	cmd = nr->cmd;
+	rsp = nr->rsp;
+	nr->cmd = NULL;
+	nr->rsp = NULL;
+	nr->used = false;
+	spin_unlock_irqrestore(&ndp->lock, flags);
+
+	/* Release command and response */
+	consume_skb(cmd);
+	consume_skb(rsp);
+}
+
+struct ncsi_dev *ncsi_find_dev(struct net_device *dev)
+{
+	struct ncsi_dev_priv *ndp;
+
+	NCSI_FOR_EACH_DEV(ndp) {
+		if (ndp->ndev.dev == dev)
+			return &ndp->ndev;
+	}
+
+	return NULL;
+}
+
+static void ncsi_request_timeout(unsigned long data)
+{
+	struct ncsi_request *nr = (struct ncsi_request *)data;
+	struct ncsi_dev_priv *ndp = nr->ndp;
+	unsigned long flags;
+
+	/* If the request already had associated response,
+	 * let the response handler to release it.
+	 */
+	spin_lock_irqsave(&ndp->lock, flags);
+	nr->enabled = false;
+	if (nr->rsp || !nr->cmd) {
+		spin_unlock_irqrestore(&ndp->lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(&ndp->lock, flags);
+
+	/* Release the request */
+	ncsi_free_request(nr);
+}
+
+struct ncsi_dev *ncsi_register_dev(struct net_device *dev,
+				   void (*handler)(struct ncsi_dev *ndev))
+{
+	struct ncsi_dev_priv *ndp;
+	struct ncsi_dev *nd;
+	unsigned long flags;
+	int i;
+
+	/* Check if the device has been registered or not */
+	nd = ncsi_find_dev(dev);
+	if (nd)
+		return nd;
+
+	/* Create NCSI device */
+	ndp = kzalloc(sizeof(*ndp), GFP_ATOMIC);
+	if (!ndp)
+		return NULL;
+
+	nd = &ndp->ndev;
+	nd->state = ncsi_dev_state_registered;
+	nd->dev = dev;
+	nd->handler = handler;
+
+	/* Initialize private NCSI device */
+	spin_lock_init(&ndp->lock);
+	INIT_LIST_HEAD(&ndp->packages);
+	ndp->request_id = 0;
+	for (i = 0; i < ARRAY_SIZE(ndp->requests); i++) {
+		ndp->requests[i].id = i;
+		ndp->requests[i].ndp = ndp;
+		setup_timer(&ndp->requests[i].timer,
+			    ncsi_request_timeout,
+			    (unsigned long)&ndp->requests[i]);
+	}
+
+	spin_lock_irqsave(&ncsi_dev_lock, flags);
+	list_add_tail_rcu(&ndp->node, &ncsi_dev_list);
+	spin_unlock_irqrestore(&ncsi_dev_lock, flags);
+
+	return nd;
+}
+EXPORT_SYMBOL_GPL(ncsi_register_dev);
+
+void ncsi_unregister_dev(struct ncsi_dev *nd)
+{
+	struct ncsi_dev_priv *ndp = TO_NCSI_DEV_PRIV(nd);
+	struct ncsi_package *np, *tmp;
+	unsigned long flags;
+
+	list_for_each_entry_safe(np, tmp, &ndp->packages, node)
+		ncsi_remove_package(np);
+
+	spin_lock_irqsave(&ncsi_dev_lock, flags);
+	list_del_rcu(&ndp->node);
+	spin_unlock_irqrestore(&ncsi_dev_lock, flags);
+
+	kfree(ndp);
+}
+EXPORT_SYMBOL_GPL(ncsi_unregister_dev);