/*
 * net/core/gen_stats.c
 *
 *             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.
 *
 * Authors:  Thomas Graf <tgraf@suug.ch>
 *           Jamal Hadi Salim
 *           Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 * See Documentation/networking/gen_stats.txt
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/socket.h>
#include <linux/rtnetlink.h>
#include <linux/gen_stats.h>
#include <net/netlink.h>
#include <net/gen_stats.h>


static inline int
gnet_stats_copy(struct gnet_dump *d, int type, void *buf, int size)
{
        if (nla_put(d->skb, type, size, buf))
                goto nla_put_failure;
        return 0;

nla_put_failure:
        kfree(d->xstats);
        d->xstats = NULL;
        d->xstats_len = 0;
        spin_unlock_bh(d->lock);
        return -1;
}

/**
 * gnet_stats_start_copy_compat - start dumping procedure in compatibility mode
 * @skb: socket buffer to put statistics TLVs into
 * @type: TLV type for top level statistic TLV
 * @tc_stats_type: TLV type for backward compatibility struct tc_stats TLV
 * @xstats_type: TLV type for backward compatibility xstats TLV
 * @lock: statistics lock
 * @d: dumping handle
 *
 * Initializes the dumping handle, grabs the statistic lock and appends
 * an empty TLV header to the socket buffer for use a container for all
 * other statistic TLVS.
 *
 * The dumping handle is marked to be in backward compatibility mode telling
 * all gnet_stats_copy_XXX() functions to fill a local copy of struct tc_stats.
 *
 * Returns 0 on success or -1 if the room in the socket buffer was not sufficient.
 */
int
gnet_stats_start_copy_compat(struct sk_buff *skb, int type, int tc_stats_type,
        int xstats_type, spinlock_t *lock, struct gnet_dump *d)
        __acquires(lock)
{
        memset(d, 0, sizeof(*d));

        spin_lock_bh(lock);
        d->lock = lock;
        if (type)
                d->tail = (struct nlattr *)skb_tail_pointer(skb);
        d->skb = skb;
        d->compat_tc_stats = tc_stats_type;
        d->compat_xstats = xstats_type;

        if (d->tail)
                return gnet_stats_copy(d, type, NULL, 0);

        return 0;
}
EXPORT_SYMBOL(gnet_stats_start_copy_compat);

/**
 * gnet_stats_start_copy_compat - start dumping procedure in compatibility mode
 * @skb: socket buffer to put statistics TLVs into
 * @type: TLV type for top level statistic TLV
 * @lock: statistics lock
 * @d: dumping handle
 *
 * Initializes the dumping handle, grabs the statistic lock and appends
 * an empty TLV header to the socket buffer for use a container for all
 * other statistic TLVS.
 *
 * Returns 0 on success or -1 if the room in the socket buffer was not sufficient.
 */
int
gnet_stats_start_copy(struct sk_buff *skb, int type, spinlock_t *lock,
        struct gnet_dump *d)
{
        return gnet_stats_start_copy_compat(skb, type, 0, 0, lock, d);
}
EXPORT_SYMBOL(gnet_stats_start_copy);

static void
__gnet_stats_copy_basic_cpu(struct gnet_stats_basic_packed *bstats,
                            struct gnet_stats_basic_cpu __percpu *cpu)
{
        int i;

        for_each_possible_cpu(i) {
                struct gnet_stats_basic_cpu *bcpu = per_cpu_ptr(cpu, i);
                unsigned int start;
                u64 bytes;
                u32 packets;

                do {
                        start = u64_stats_fetch_begin_irq(&bcpu->syncp);
                        bytes = bcpu->bstats.bytes;
                        packets = bcpu->bstats.packets;
                } while (u64_stats_fetch_retry_irq(&bcpu->syncp, start));

                bstats->bytes += bytes;
                bstats->packets += packets;
        }
}

void
__gnet_stats_copy_basic(struct gnet_stats_basic_packed *bstats,
                        struct gnet_stats_basic_cpu __percpu *cpu,
                        struct gnet_stats_basic_packed *b)
{
        if (cpu) {
                __gnet_stats_copy_basic_cpu(bstats, cpu);
        } else {
                bstats->bytes = b->bytes;
                bstats->packets = b->packets;
        }
}
EXPORT_SYMBOL(__gnet_stats_copy_basic);

/**
 * gnet_stats_copy_basic - copy basic statistics into statistic TLV
 * @d: dumping handle
 * @b: basic statistics
 *
 * Appends the basic statistics to the top level TLV created by
 * gnet_stats_start_copy().
 *
 * Returns 0 on success or -1 with the statistic lock released
 * if the room in the socket buffer was not sufficient.
 */
int
gnet_stats_copy_basic(struct gnet_dump *d,
                      struct gnet_stats_basic_cpu __percpu *cpu,
                      struct gnet_stats_basic_packed *b)
{
        struct gnet_stats_basic_packed bstats = {0};

        __gnet_stats_copy_basic(&bstats, cpu, b);

        if (d->compat_tc_stats) {
                d->tc_stats.bytes = bstats.bytes;
                d->tc_stats.packets = bstats.packets;
        }

        if (d->tail) {
                struct gnet_stats_basic sb;

                memset(&sb, 0, sizeof(sb));
                sb.bytes = bstats.bytes;
                sb.packets = bstats.packets;
                return gnet_stats_copy(d, TCA_STATS_BASIC, &sb, sizeof(sb));
        }
        return 0;
}
EXPORT_SYMBOL(gnet_stats_copy_basic);

/**
 * gnet_stats_copy_rate_est - copy rate estimator statistics into statistics TLV
 * @d: dumping handle
 * @b: basic statistics
 * @r: rate estimator statistics
 *
 * Appends the rate estimator statistics to the top level TLV created by
 * gnet_stats_start_copy().
 *
 * Returns 0 on success or -1 with the statistic lock released
 * if the room in the socket buffer was not sufficient.
 */
int
gnet_stats_copy_rate_est(struct gnet_dump *d,
                         const struct gnet_stats_basic_packed *b,
                         struct gnet_stats_rate_est64 *r)
{
        struct gnet_stats_rate_est est;
        int res;

        if (b && !gen_estimator_active(b, r))
                return 0;

        est.bps = min_t(u64, UINT_MAX, r->bps);
        /* we have some time before reaching 2^32 packets per second */
        est.pps = r->pps;

        if (d->compat_tc_stats) {
                d->tc_stats.bps = est.bps;
                d->tc_stats.pps = est.pps;
        }

        if (d->tail) {
                res = gnet_stats_copy(d, TCA_STATS_RATE_EST, &est, sizeof(est));
                if (res < 0 || est.bps == r->bps)
                        return res;
                /* emit 64bit stats only if needed */
                return gnet_stats_copy(d, TCA_STATS_RATE_EST64, r, sizeof(*r));
        }

        return 0;
}
EXPORT_SYMBOL(gnet_stats_copy_rate_est);

static void
__gnet_stats_copy_queue_cpu(struct gnet_stats_queue *qstats,
                            const struct gnet_stats_queue __percpu *q)
{
        int i;

        for_each_possible_cpu(i) {
                const struct gnet_stats_queue *qcpu = per_cpu_ptr(q, i);

                qstats->qlen = 0;
                qstats->backlog += qcpu->backlog;
                qstats->drops += qcpu->drops;
                qstats->requeues += qcpu->requeues;
                qstats->overlimits += qcpu->overlimits;
        }
}

static void __gnet_stats_copy_queue(struct gnet_stats_queue *qstats,
                                    const struct gnet_stats_queue __percpu *cpu,
                                    const struct gnet_stats_queue *q,
                                    __u32 qlen)
{
        if (cpu) {
                __gnet_stats_copy_queue_cpu(qstats, cpu);
        } else {
                qstats->qlen = q->qlen;
                qstats->backlog = q->backlog;
                qstats->drops = q->drops;
                qstats->requeues = q->requeues;
                qstats->overlimits = q->overlimits;
        }

        qstats->qlen = qlen;
}

/**
 * gnet_stats_copy_queue - copy queue statistics into statistics TLV
 * @d: dumping handle
 * @cpu_q: per cpu queue statistics
 * @q: queue statistics
 * @qlen: queue length statistics
 *
 * Appends the queue statistics to the top level TLV created by
 * gnet_stats_start_copy(). Using per cpu queue statistics if
 * they are available.
 *
 * Returns 0 on success or -1 with the statistic lock released
 * if the room in the socket buffer was not sufficient.
 */
int
gnet_stats_copy_queue(struct gnet_dump *d,
                      struct gnet_stats_queue __percpu *cpu_q,
                      struct gnet_stats_queue *q, __u32 qlen)
{
        struct gnet_stats_queue qstats = {0};

        __gnet_stats_copy_queue(&qstats, cpu_q, q, qlen);

        if (d->compat_tc_stats) {
                d->tc_stats.drops = qstats.drops;
                d->tc_stats.qlen = qstats.qlen;
                d->tc_stats.backlog = qstats.backlog;
                d->tc_stats.overlimits = qstats.overlimits;
        }

        if (d->tail)
                return gnet_stats_copy(d, TCA_STATS_QUEUE,
                                       &qstats, sizeof(qstats));

        return 0;
}
EXPORT_SYMBOL(gnet_stats_copy_queue);

/**
 * gnet_stats_copy_app - copy application specific statistics into statistics TLV
 * @d: dumping handle
 * @st: application specific statistics data
 * @len: length of data
 *
 * Appends the application specific statistics to the top level TLV created by
 * gnet_stats_start_copy() and remembers the data for XSTATS if the dumping
 * handle is in backward compatibility mode.
 *
 * Returns 0 on success or -1 with the statistic lock released
 * if the room in the socket buffer was not sufficient.
 */
int
gnet_stats_copy_app(struct gnet_dump *d, void *st, int len)
{
        if (d->compat_xstats) {
                d->xstats = kmemdup(st, len, GFP_ATOMIC);
                if (!d->xstats)
                        goto err_out;
                d->xstats_len = len;
        }

        if (d->tail)
                return gnet_stats_copy(d, TCA_STATS_APP, st, len);

        return 0;

err_out:
        d->xstats_len = 0;
        spin_unlock_bh(d->lock);
        return -1;
}
EXPORT_SYMBOL(gnet_stats_copy_app);

/**
 * gnet_stats_finish_copy - finish dumping procedure
 * @d: dumping handle
 *
 * Corrects the length of the top level TLV to include all TLVs added
 * by gnet_stats_copy_XXX() calls. Adds the backward compatibility TLVs
 * if gnet_stats_start_copy_compat() was used and releases the statistics
 * lock.
 *
 * Returns 0 on success or -1 with the statistic lock released
 * if the room in the socket buffer was not sufficient.
 */
int
gnet_stats_finish_copy(struct gnet_dump *d)
{
        if (d->tail)
                d->tail->nla_len = skb_tail_pointer(d->skb) - (u8 *)d->tail;

        if (d->compat_tc_stats)
                if (gnet_stats_copy(d, d->compat_tc_stats, &d->tc_stats,
                        sizeof(d->tc_stats)) < 0)
                        return -1;

        if (d->compat_xstats && d->xstats) {
                if (gnet_stats_copy(d, d->compat_xstats, d->xstats,
                        d->xstats_len) < 0)
                        return -1;
        }

        kfree(d->xstats);
        d->xstats = NULL;
        d->xstats_len = 0;
        spin_unlock_bh(d->lock);
        return 0;
}
EXPORT_SYMBOL(gnet_stats_finish_copy);