// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/core/gen_stats.c
 *
 * Authors:  Thomas Graf <tgraf@suug.ch>
 *           Jamal Hadi Salim
 *           Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 * See Documentation/networking/gen_stats.rst
 */

#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>
#include <net/sch_generic.h>

static inline int
gnet_stats_copy(struct gnet_dump *d, int type, void *buf, int size, int padattr)
{
        if (nla_put_64bit(d->skb, type, size, buf, padattr))
                goto nla_put_failure;
        return 0;

nla_put_failure:
        if (d->lock)
                spin_unlock_bh(d->lock);
        kfree(d->xstats);
        d->xstats = NULL;
        d->xstats_len = 0;
        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
 * @padattr: padding attribute
 *
 * 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, int padattr)
        __acquires(lock)
{
        memset(d, 0, sizeof(*d));

        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;
        d->padattr = padattr;
        if (lock) {
                d->lock = lock;
                spin_lock_bh(lock);
        }
        if (d->tail) {
                int ret = gnet_stats_copy(d, type, NULL, 0, padattr);

                /* The initial attribute added in gnet_stats_copy() may be
                 * preceded by a padding attribute, in which case d->tail will
                 * end up pointing at the padding instead of the real attribute.
                 * Fix this so gnet_stats_finish_copy() adjusts the length of
                 * the right attribute.
                 */
                if (ret == 0 && d->tail->nla_type == padattr)
                        d->tail = (struct nlattr *)((char *)d->tail +
                                                    NLA_ALIGN(d->tail->nla_len));
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL(gnet_stats_start_copy_compat);

/**
 * gnet_stats_start_copy - 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
 * @padattr: padding attribute
 *
 * 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, int padattr)
{
        return gnet_stats_start_copy_compat(skb, type, 0, 0, lock, d, padattr);
}
EXPORT_SYMBOL(gnet_stats_start_copy);

/* Must not be inlined, due to u64_stats seqcount_t lockdep key */
void gnet_stats_basic_sync_init(struct gnet_stats_basic_sync *b)
{
        u64_stats_set(&b->bytes, 0);
        u64_stats_set(&b->packets, 0);
        u64_stats_init(&b->syncp);
}
EXPORT_SYMBOL(gnet_stats_basic_sync_init);

static void gnet_stats_add_basic_cpu(struct gnet_stats_basic_sync *bstats,
                                     struct gnet_stats_basic_sync __percpu *cpu)
{
        u64 t_bytes = 0, t_packets = 0;
        int i;

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

                do {
                        start = u64_stats_fetch_begin(&bcpu->syncp);
                        bytes = u64_stats_read(&bcpu->bytes);
                        packets = u64_stats_read(&bcpu->packets);
                } while (u64_stats_fetch_retry(&bcpu->syncp, start));

                t_bytes += bytes;
                t_packets += packets;
        }
        _bstats_update(bstats, t_bytes, t_packets);
}

void gnet_stats_add_basic(struct gnet_stats_basic_sync *bstats,
                          struct gnet_stats_basic_sync __percpu *cpu,
                          struct gnet_stats_basic_sync *b, bool running)
{
        unsigned int start;
        u64 bytes = 0;
        u64 packets = 0;

        WARN_ON_ONCE((cpu || running) && in_hardirq());

        if (cpu) {
                gnet_stats_add_basic_cpu(bstats, cpu);
                return;
        }
        do {
                if (running)
                        start = u64_stats_fetch_begin(&b->syncp);
                bytes = u64_stats_read(&b->bytes);
                packets = u64_stats_read(&b->packets);
        } while (running && u64_stats_fetch_retry(&b->syncp, start));

        _bstats_update(bstats, bytes, packets);
}
EXPORT_SYMBOL(gnet_stats_add_basic);

static void gnet_stats_read_basic(u64 *ret_bytes, u64 *ret_packets,
                                  struct gnet_stats_basic_sync __percpu *cpu,
                                  struct gnet_stats_basic_sync *b, bool running)
{
        unsigned int start;

        if (cpu) {
                u64 t_bytes = 0, t_packets = 0;
                int i;

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

                        do {
                                start = u64_stats_fetch_begin(&bcpu->syncp);
                                bytes = u64_stats_read(&bcpu->bytes);
                                packets = u64_stats_read(&bcpu->packets);
                        } while (u64_stats_fetch_retry(&bcpu->syncp, start));

                        t_bytes += bytes;
                        t_packets += packets;
                }
                *ret_bytes = t_bytes;
                *ret_packets = t_packets;
                return;
        }
        do {
                if (running)
                        start = u64_stats_fetch_begin(&b->syncp);
                *ret_bytes = u64_stats_read(&b->bytes);
                *ret_packets = u64_stats_read(&b->packets);
        } while (running && u64_stats_fetch_retry(&b->syncp, start));
}

static int
___gnet_stats_copy_basic(struct gnet_dump *d,
                         struct gnet_stats_basic_sync __percpu *cpu,
                         struct gnet_stats_basic_sync *b,
                         int type, bool running)
{
        u64 bstats_bytes, bstats_packets;

        gnet_stats_read_basic(&bstats_bytes, &bstats_packets, cpu, b, running);

        if (d->compat_tc_stats && type == TCA_STATS_BASIC) {
                d->tc_stats.bytes = bstats_bytes;
                d->tc_stats.packets = bstats_packets;
        }

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

                memset(&sb, 0, sizeof(sb));
                sb.bytes = bstats_bytes;
                sb.packets = bstats_packets;
                res = gnet_stats_copy(d, type, &sb, sizeof(sb), TCA_STATS_PAD);
                if (res < 0 || sb.packets == bstats_packets)
                        return res;
                /* emit 64bit stats only if needed */
                return gnet_stats_copy(d, TCA_STATS_PKT64, &bstats_packets,
                                       sizeof(bstats_packets), TCA_STATS_PAD);
        }
        return 0;
}

/**
 * gnet_stats_copy_basic - copy basic statistics into statistic TLV
 * @d: dumping handle
 * @cpu: copy statistic per cpu
 * @b: basic statistics
 * @running: true if @b represents a running qdisc, thus @b's
 *           internal values might change during basic reads.
 *           Only used if @cpu is NULL
 *
 * Context: task; must not be run from IRQ or BH contexts
 *
 * 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_sync __percpu *cpu,
                      struct gnet_stats_basic_sync *b,
                      bool running)
{
        return ___gnet_stats_copy_basic(d, cpu, b, TCA_STATS_BASIC, running);
}
EXPORT_SYMBOL(gnet_stats_copy_basic);

/**
 * gnet_stats_copy_basic_hw - copy basic hw statistics into statistic TLV
 * @d: dumping handle
 * @cpu: copy statistic per cpu
 * @b: basic statistics
 * @running: true if @b represents a running qdisc, thus @b's
 *           internal values might change during basic reads.
 *           Only used if @cpu is NULL
 *
 * Context: task; must not be run from IRQ or BH contexts
 *
 * 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_hw(struct gnet_dump *d,
                         struct gnet_stats_basic_sync __percpu *cpu,
                         struct gnet_stats_basic_sync *b,
                         bool running)
{
        return ___gnet_stats_copy_basic(d, cpu, b, TCA_STATS_BASIC_HW, running);
}
EXPORT_SYMBOL(gnet_stats_copy_basic_hw);

/**
 * gnet_stats_copy_rate_est - copy rate estimator statistics into statistics TLV
 * @d: dumping handle
 * @rate_est: rate estimator
 *
 * 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,
                         struct net_rate_estimator __rcu **rate_est)
{
        struct gnet_stats_rate_est64 sample;
        struct gnet_stats_rate_est est;
        int res;

        if (!gen_estimator_read(rate_est, &sample))
                return 0;
        est.bps = min_t(u64, UINT_MAX, sample.bps);
        /* we have some time before reaching 2^32 packets per second */
        est.pps = sample.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),
                                      TCA_STATS_PAD);
                if (res < 0 || est.bps == sample.bps)
                        return res;
                /* emit 64bit stats only if needed */
                return gnet_stats_copy(d, TCA_STATS_RATE_EST64, &sample,
                                       sizeof(sample), TCA_STATS_PAD);
        }

        return 0;
}
EXPORT_SYMBOL(gnet_stats_copy_rate_est);

static void gnet_stats_add_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 += qcpu->qlen;
                qstats->backlog += qcpu->backlog;
                qstats->drops += qcpu->drops;
                qstats->requeues += qcpu->requeues;
                qstats->overlimits += qcpu->overlimits;
        }
}

void gnet_stats_add_queue(struct gnet_stats_queue *qstats,
                          const struct gnet_stats_queue __percpu *cpu,
                          const struct gnet_stats_queue *q)
{
        if (cpu) {
                gnet_stats_add_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;
        }
}
EXPORT_SYMBOL(gnet_stats_add_queue);

/**
 * 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_add_queue(&qstats, cpu_q, q);
        qstats.qlen = 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),
                                       TCA_STATS_PAD);

        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,
                                       TCA_STATS_PAD);

        return 0;

err_out:
        if (d->lock)
                spin_unlock_bh(d->lock);
        d->xstats_len = 0;
        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), d->padattr) < 0)
                        return -1;

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

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