/*      $NetBSD: wqinput.c,v 1.8 2020/02/07 12:35:33 thorpej Exp $      */

/*-
* Copyright (c) 2017 Internet Initiative Japan Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#ifdef _KERNEL_OPT
#include "opt_net_mpsafe.h"
#endif

#include <sys/param.h>
#include <sys/kmem.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socketvar.h>
#include <sys/syslog.h>
#include <sys/workqueue.h>
#include <sys/atomic.h>
#include <sys/queue.h>
#include <sys/percpu.h>
#include <sys/sysctl.h>
#include <sys/xcall.h>

#include <net/if.h>
#include <netinet/wqinput.h>

#define WQINPUT_LIST_MAXLEN     IFQ_MAXLEN

struct wqinput_work {
       struct mbuf     *ww_mbuf;
       int             ww_off;
       int             ww_proto;
       struct wqinput_work *ww_next;
};

struct wqinput_worklist {
       /*
        * XXX: TAILQ cannot be used because TAILQ_INIT memories the address
        * of percpu data while percpu(9) may move percpu data during bootup.
        */
       struct wqinput_work *wwl_head;
       struct wqinput_work *wwl_tail;
       unsigned int    wwl_len;
       uint64_t        wwl_dropped;
       struct work     wwl_work;
       bool            wwl_wq_is_active;
};

struct wqinput {
       struct workqueue *wqi_wq;
       struct pool     wqi_work_pool;
       struct percpu   *wqi_worklists; /* struct wqinput_worklist */
       void            (*wqi_input)(struct mbuf *, int, int);
};

static void wqinput_work(struct work *, void *);
static void wqinput_sysctl_setup(const char *, struct wqinput *);

static void
wqinput_drops(void *p, void *arg, struct cpu_info *ci __unused)
{
       struct wqinput_worklist **const wwlp = p;
       struct wqinput_worklist *const wwl = *wwlp;
       uint64_t *sum = arg;

       *sum += wwl->wwl_dropped;
}

static int
wqinput_sysctl_drops_handler(SYSCTLFN_ARGS)
{
       struct sysctlnode node;
       struct wqinput *wqi;
       uint64_t sum = 0;
       int error;

       node = *rnode;
       wqi = node.sysctl_data;

       percpu_foreach_xcall(wqi->wqi_worklists, XC_HIGHPRI_IPL(IPL_SOFTNET),
           wqinput_drops, &sum);

       node.sysctl_data = &sum;
       error = sysctl_lookup(SYSCTLFN_CALL(&node));
       if (error != 0 || newp == NULL)
               return error;

       return 0;
}

static void
wqinput_sysctl_setup(const char *name, struct wqinput *wqi)
{
       const struct sysctlnode *cnode, *rnode;
       int error;

       error = sysctl_createv(NULL, 0, NULL, &rnode,
           CTLFLAG_PERMANENT, CTLTYPE_NODE, "wqinput",
           SYSCTL_DESCR("workqueue-based pr_input controls"),
           NULL, 0, NULL, 0, CTL_NET, CTL_CREATE, CTL_EOL);
       if (error != 0)
               goto bad;

       error = sysctl_createv(NULL, 0, &rnode, &rnode,
           CTLFLAG_PERMANENT, CTLTYPE_NODE, name,
           SYSCTL_DESCR("Protocol controls for workqueue-based pr_input"),
           NULL, 0, NULL, 0, CTL_CREATE, CTL_EOL);
       if (error != 0)
               goto bad;

       error = sysctl_createv(NULL, 0, &rnode, &rnode,
           CTLFLAG_PERMANENT, CTLTYPE_NODE, "inputq",
           SYSCTL_DESCR("wqinput input queue controls"),
           NULL, 0, NULL, 0, CTL_CREATE, CTL_EOL);
       if (error != 0)
               goto bad;

       error = sysctl_createv(NULL, 0, &rnode, &cnode,
           CTLFLAG_PERMANENT, CTLTYPE_QUAD, "drops",
           SYSCTL_DESCR("Total packets dropped due to full input queue"),
           wqinput_sysctl_drops_handler, 0, (void *)wqi, 0, CTL_CREATE, CTL_EOL);
       if (error != 0)
               goto bad;

       return;
bad:
       log(LOG_ERR, "%s: could not create a sysctl node for %s\n",
           __func__, name);
       return;
}

static struct wqinput_worklist *
wqinput_percpu_getref(percpu_t *pc)
{

       return *(struct wqinput_worklist **)percpu_getref(pc);
}

static void
wqinput_percpu_putref(percpu_t *pc)
{

       percpu_putref(pc);
}

static void
wqinput_percpu_init_cpu(void *p, void *arg __unused, struct cpu_info *ci __unused)
{
       struct wqinput_worklist **wwlp = p;

       *wwlp = kmem_zalloc(sizeof(**wwlp), KM_SLEEP);
}

struct wqinput *
wqinput_create(const char *name, void (*func)(struct mbuf *, int, int))
{
       struct wqinput *wqi;
       int error;
       char namebuf[32];

       snprintf(namebuf, sizeof(namebuf), "%s_wqinput", name);

       wqi = kmem_alloc(sizeof(*wqi), KM_SLEEP);

       error = workqueue_create(&wqi->wqi_wq, namebuf, wqinput_work, wqi,
           PRI_SOFTNET, IPL_SOFTNET, WQ_MPSAFE|WQ_PERCPU);
       if (error != 0)
               panic("%s: workqueue_create failed (%d)\n", __func__, error);
       pool_init(&wqi->wqi_work_pool, sizeof(struct wqinput_work), 0, 0, 0,
           name, NULL, IPL_SOFTNET);
       wqi->wqi_worklists = percpu_create(sizeof(struct wqinput_worklist *),
           wqinput_percpu_init_cpu, NULL, NULL);
       wqi->wqi_input = func;

       wqinput_sysctl_setup(name, wqi);

       return wqi;
}

static struct wqinput_work *
wqinput_work_get(struct wqinput_worklist *wwl)
{
       struct wqinput_work *work;

       /* Must be called at IPL_SOFTNET */

       work = wwl->wwl_head;
       if (work != NULL) {
               KASSERTMSG(wwl->wwl_len > 0, "wwl->wwl_len=%d", wwl->wwl_len);
               wwl->wwl_len--;
               wwl->wwl_head = work->ww_next;
               work->ww_next = NULL;

               if (wwl->wwl_head == NULL)
                       wwl->wwl_tail = NULL;
       } else {
               KASSERT(wwl->wwl_len == 0);
       }

       return work;
}

static void
wqinput_work(struct work *wk, void *arg)
{
       struct wqinput *wqi = arg;
       struct wqinput_work *work;
       struct wqinput_worklist *wwl;
       int s;

       /* Users expect to run at IPL_SOFTNET */
       s = splsoftnet();
       /* This also prevents LWP migrations between CPUs */
       wwl = wqinput_percpu_getref(wqi->wqi_worklists);

       /* We can allow enqueuing another work at this point */
       wwl->wwl_wq_is_active = false;

       while ((work = wqinput_work_get(wwl)) != NULL) {
               mutex_enter(softnet_lock);
               KERNEL_LOCK_UNLESS_NET_MPSAFE();
               wqi->wqi_input(work->ww_mbuf, work->ww_off, work->ww_proto);
               KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
               mutex_exit(softnet_lock);

               pool_put(&wqi->wqi_work_pool, work);
       }

       wqinput_percpu_putref(wqi->wqi_worklists);
       splx(s);
}

static void
wqinput_work_put(struct wqinput_worklist *wwl, struct wqinput_work *work)
{

       if (wwl->wwl_tail != NULL) {
               wwl->wwl_tail->ww_next = work;
       } else {
               wwl->wwl_head = work;
       }
       wwl->wwl_tail = work;
       wwl->wwl_len++;
}

void
wqinput_input(struct wqinput *wqi, struct mbuf *m, int off, int proto)
{
       struct wqinput_work *work;
       struct wqinput_worklist *wwl;

       wwl = wqinput_percpu_getref(wqi->wqi_worklists);

       /* Prevent too much work and mbuf from being queued */
       if (wwl->wwl_len >= WQINPUT_LIST_MAXLEN) {
               wwl->wwl_dropped++;
               m_freem(m);
               goto out;
       }

       work = pool_get(&wqi->wqi_work_pool, PR_NOWAIT);
       if (work == NULL) {
               wwl->wwl_dropped++;
               m_freem(m);
               goto out;
       }
       work->ww_mbuf = m;
       work->ww_off = off;
       work->ww_proto = proto;
       work->ww_next = NULL;

       wqinput_work_put(wwl, work);

       /* Avoid enqueuing another work when one is already enqueued */
       if (wwl->wwl_wq_is_active)
               goto out;
       wwl->wwl_wq_is_active = true;

       workqueue_enqueue(wqi->wqi_wq, &wwl->wwl_work, NULL);
out:
       wqinput_percpu_putref(wqi->wqi_worklists);
}

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