// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2010 Red Hat, Inc.  All rights reserved.
**
**
*******************************************************************************
******************************************************************************/

#include <trace/events/dlm.h>

#include "dlm_internal.h"
#include "lvb_table.h"
#include "memory.h"
#include "lock.h"
#include "user.h"
#include "ast.h"

static void dlm_run_callback(uint32_t ls_id, uint32_t lkb_id, int8_t mode,
                             uint32_t flags, uint8_t sb_flags, int sb_status,
                             struct dlm_lksb *lksb,
                             void (*astfn)(void *astparam),
                             void (*bastfn)(void *astparam, int mode),
                             void *astparam, const char *res_name,
                             size_t res_length)
{
        if (flags & DLM_CB_BAST) {
                trace_dlm_bast(ls_id, lkb_id, mode, res_name, res_length);
                bastfn(astparam, mode);
        } else if (flags & DLM_CB_CAST) {
                trace_dlm_ast(ls_id, lkb_id, sb_flags, sb_status, res_name,
                              res_length);
                lksb->sb_status = sb_status;
                lksb->sb_flags = sb_flags;
                astfn(astparam);
        }
}

static void dlm_do_callback(struct dlm_callback *cb)
{
        dlm_run_callback(cb->ls_id, cb->lkb_id, cb->mode, cb->flags,
                         cb->sb_flags, cb->sb_status, cb->lkb_lksb,
                         cb->astfn, cb->bastfn, cb->astparam,
                         cb->res_name, cb->res_length);
        dlm_free_cb(cb);
}

static void dlm_callback_work(struct work_struct *work)
{
        struct dlm_callback *cb = container_of(work, struct dlm_callback, work);

        dlm_do_callback(cb);
}

bool dlm_may_skip_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
                           int status, uint32_t sbflags, int *copy_lvb)
{
        struct dlm_rsb *rsb = lkb->lkb_resource;
        struct dlm_ls *ls = rsb->res_ls;
        int prev_mode;

        if (copy_lvb)
                *copy_lvb = 0;

        if (flags & DLM_CB_BAST) {
                /* if cb is a bast, it should be skipped if the blocking mode is
                 * compatible with the last granted mode
                 */
                if (lkb->lkb_last_cast_cb_mode != -1) {
                        if (dlm_modes_compat(mode, lkb->lkb_last_cast_cb_mode)) {
                                log_debug(ls, "skip %x bast mode %d for cast mode %d",
                                          lkb->lkb_id, mode,
                                          lkb->lkb_last_cast_cb_mode);
                                return true;
                        }
                }

                /*
                 * Suppress some redundant basts here, do more on removal.
                 * Don't even add a bast if the callback just before it
                 * is a bast for the same mode or a more restrictive mode.
                 * (the addional > PR check is needed for PR/CW inversion)
                 */
                if (lkb->lkb_last_cb_mode != -1 &&
                    lkb->lkb_last_cb_flags & DLM_CB_BAST) {
                        prev_mode = lkb->lkb_last_cb_mode;

                        if ((prev_mode == mode) ||
                            (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
                                log_debug(ls, "skip %x add bast mode %d for bast mode %d",
                                          lkb->lkb_id, mode, prev_mode);
                                return true;
                        }
                }

                lkb->lkb_last_bast_time = ktime_get();
                lkb->lkb_last_bast_cb_mode = mode;
        } else if (flags & DLM_CB_CAST) {
                if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
                        prev_mode = lkb->lkb_last_cast_cb_mode;

                        if (!status && lkb->lkb_lksb->sb_lvbptr &&
                            dlm_lvb_operations[prev_mode + 1][mode + 1]) {
                                if (copy_lvb)
                                        *copy_lvb = 1;
                        }
                }

                lkb->lkb_last_cast_cb_mode = mode;
                lkb->lkb_last_cast_time = ktime_get();
        }

        lkb->lkb_last_cb_mode = mode;
        lkb->lkb_last_cb_flags = flags;

        return false;
}

int dlm_get_cb(struct dlm_lkb *lkb, uint32_t flags, int mode,
               int status, uint32_t sbflags,
               struct dlm_callback **cb)
{
        struct dlm_rsb *rsb = lkb->lkb_resource;
        struct dlm_ls *ls = rsb->res_ls;

        *cb = dlm_allocate_cb();
        if (WARN_ON_ONCE(!*cb))
                return -ENOMEM;

        /* for tracing */
        (*cb)->lkb_id = lkb->lkb_id;
        (*cb)->ls_id = ls->ls_global_id;
        memcpy((*cb)->res_name, rsb->res_name, rsb->res_length);
        (*cb)->res_length = rsb->res_length;

        (*cb)->flags = flags;
        (*cb)->mode = mode;
        (*cb)->sb_status = status;
        (*cb)->sb_flags = (sbflags & 0x000000FF);
        (*cb)->lkb_lksb = lkb->lkb_lksb;

        return 0;
}

static int dlm_get_queue_cb(struct dlm_lkb *lkb, uint32_t flags, int mode,
                            int status, uint32_t sbflags,
                            struct dlm_callback **cb)
{
        int rv;

        rv = dlm_get_cb(lkb, flags, mode, status, sbflags, cb);
        if (rv)
                return rv;

        (*cb)->astfn = lkb->lkb_astfn;
        (*cb)->bastfn = lkb->lkb_bastfn;
        (*cb)->astparam = lkb->lkb_astparam;
        INIT_WORK(&(*cb)->work, dlm_callback_work);

        return 0;
}

void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
                uint32_t sbflags)
{
        struct dlm_rsb *rsb = lkb->lkb_resource;
        struct dlm_ls *ls = rsb->res_ls;
        struct dlm_callback *cb;
        int rv;

        if (test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
                dlm_user_add_ast(lkb, flags, mode, status, sbflags);
                return;
        }

        if (dlm_may_skip_callback(lkb, flags, mode, status, sbflags, NULL))
                return;

        spin_lock_bh(&ls->ls_cb_lock);
        if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
                rv = dlm_get_queue_cb(lkb, flags, mode, status, sbflags, &cb);
                if (!rv)
                        list_add(&cb->list, &ls->ls_cb_delay);
        } else {
                if (test_bit(LSFL_SOFTIRQ, &ls->ls_flags)) {
                        dlm_run_callback(ls->ls_global_id, lkb->lkb_id, mode, flags,
                                         sbflags, status, lkb->lkb_lksb,
                                         lkb->lkb_astfn, lkb->lkb_bastfn,
                                         lkb->lkb_astparam, rsb->res_name,
                                         rsb->res_length);
                } else {
                        rv = dlm_get_queue_cb(lkb, flags, mode, status, sbflags, &cb);
                        if (!rv)
                                queue_work(ls->ls_callback_wq, &cb->work);
                }
        }
        spin_unlock_bh(&ls->ls_cb_lock);
}

int dlm_callback_start(struct dlm_ls *ls)
{
        if (!test_bit(LSFL_FS, &ls->ls_flags) ||
            test_bit(LSFL_SOFTIRQ, &ls->ls_flags))
                return 0;

        ls->ls_callback_wq = alloc_ordered_workqueue("dlm_callback",
                                                     WQ_HIGHPRI | WQ_MEM_RECLAIM);
        if (!ls->ls_callback_wq) {
                log_print("can't start dlm_callback workqueue");
                return -ENOMEM;
        }
        return 0;
}

void dlm_callback_stop(struct dlm_ls *ls)
{
        if (ls->ls_callback_wq)
                destroy_workqueue(ls->ls_callback_wq);
}

void dlm_callback_suspend(struct dlm_ls *ls)
{
        if (!test_bit(LSFL_FS, &ls->ls_flags))
                return;

        spin_lock_bh(&ls->ls_cb_lock);
        set_bit(LSFL_CB_DELAY, &ls->ls_flags);
        spin_unlock_bh(&ls->ls_cb_lock);

        if (ls->ls_callback_wq)
                flush_workqueue(ls->ls_callback_wq);
}

#define MAX_CB_QUEUE 25

void dlm_callback_resume(struct dlm_ls *ls)
{
        struct dlm_callback *cb, *safe;
        int count = 0, sum = 0;
        bool empty;

        if (!test_bit(LSFL_FS, &ls->ls_flags))
                return;

more:
        spin_lock_bh(&ls->ls_cb_lock);
        list_for_each_entry_safe(cb, safe, &ls->ls_cb_delay, list) {
                list_del(&cb->list);
                if (test_bit(LSFL_SOFTIRQ, &ls->ls_flags))
                        dlm_do_callback(cb);
                else
                        queue_work(ls->ls_callback_wq, &cb->work);

                count++;
                if (count == MAX_CB_QUEUE)
                        break;
        }
        empty = list_empty(&ls->ls_cb_delay);
        if (empty)
                clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
        spin_unlock_bh(&ls->ls_cb_lock);

        sum += count;
        if (!empty) {
                count = 0;
                cond_resched();
                goto more;
        }

        if (sum)
                log_rinfo(ls, "%s %d", __func__, sum);
}