/*
 * Copyright (c) 2016 Oracle.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "ib_mr.h"

static inline void
rds_transition_frwr_state(struct rds_ib_mr *ibmr,
                          enum rds_ib_fr_state old_state,
                          enum rds_ib_fr_state new_state)
{
        if (cmpxchg(&ibmr->u.frmr.fr_state,
                    old_state, new_state) == old_state &&
            old_state == FRMR_IS_INUSE) {
                /* enforce order of ibmr->u.frmr.fr_state update
                 * before decrementing i_fastreg_inuse_count
                 */
                smp_mb__before_atomic();
                atomic_dec(&ibmr->ic->i_fastreg_inuse_count);
                if (waitqueue_active(&rds_ib_ring_empty_wait))
                        wake_up(&rds_ib_ring_empty_wait);
        }
}

static struct rds_ib_mr *rds_ib_alloc_frmr(struct rds_ib_device *rds_ibdev,
                                           int npages)
{
        struct rds_ib_mr_pool *pool;
        struct rds_ib_mr *ibmr = NULL;
        struct rds_ib_frmr *frmr;
        int err = 0;

        if (npages <= RDS_MR_8K_MSG_SIZE)
                pool = rds_ibdev->mr_8k_pool;
        else
                pool = rds_ibdev->mr_1m_pool;

        ibmr = rds_ib_try_reuse_ibmr(pool);
        if (ibmr)
                return ibmr;

        ibmr = kzalloc_node(sizeof(*ibmr), GFP_KERNEL,
                            rdsibdev_to_node(rds_ibdev));
        if (!ibmr) {
                err = -ENOMEM;
                goto out_no_cigar;
        }

        frmr = &ibmr->u.frmr;
        frmr->mr = ib_alloc_mr(rds_ibdev->pd, IB_MR_TYPE_MEM_REG,
                         pool->max_pages);
        if (IS_ERR(frmr->mr)) {
                pr_warn("RDS/IB: %s failed to allocate MR", __func__);
                err = PTR_ERR(frmr->mr);
                goto out_no_cigar;
        }

        ibmr->pool = pool;
        if (pool->pool_type == RDS_IB_MR_8K_POOL)
                rds_ib_stats_inc(s_ib_rdma_mr_8k_alloc);
        else
                rds_ib_stats_inc(s_ib_rdma_mr_1m_alloc);

        if (atomic_read(&pool->item_count) > pool->max_items_soft)
                pool->max_items_soft = pool->max_items;

        frmr->fr_state = FRMR_IS_FREE;
        init_waitqueue_head(&frmr->fr_inv_done);
        init_waitqueue_head(&frmr->fr_reg_done);
        return ibmr;

out_no_cigar:
        kfree(ibmr);
        atomic_dec(&pool->item_count);
        return ERR_PTR(err);
}

static void rds_ib_free_frmr(struct rds_ib_mr *ibmr, bool drop)
{
        struct rds_ib_mr_pool *pool = ibmr->pool;

        if (drop)
                llist_add(&ibmr->llnode, &pool->drop_list);
        else
                llist_add(&ibmr->llnode, &pool->free_list);
        atomic_add(ibmr->sg_len, &pool->free_pinned);
        atomic_inc(&pool->dirty_count);

        /* If we've pinned too many pages, request a flush */
        if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
            atomic_read(&pool->dirty_count) >= pool->max_items / 5)
                queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);
}

static int rds_ib_post_reg_frmr(struct rds_ib_mr *ibmr)
{
        struct rds_ib_frmr *frmr = &ibmr->u.frmr;
        struct ib_reg_wr reg_wr;
        int ret, off = 0;

        while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
                atomic_inc(&ibmr->ic->i_fastreg_wrs);
                cpu_relax();
        }

        ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_dma_len,
                                &off, PAGE_SIZE);
        if (unlikely(ret != ibmr->sg_dma_len)) {
                ret = ret < 0 ? ret : -EINVAL;
                goto out_inc;
        }

        if (cmpxchg(&frmr->fr_state, FRMR_IS_FREE, FRMR_IS_INUSE) != FRMR_IS_FREE) {
                ret = -EBUSY;
                goto out_inc;
        }

        atomic_inc(&ibmr->ic->i_fastreg_inuse_count);

        /* Perform a WR for the fast_reg_mr. Each individual page
         * in the sg list is added to the fast reg page list and placed
         * inside the fast_reg_mr WR.  The key used is a rolling 8bit
         * counter, which should guarantee uniqueness.
         */
        ib_update_fast_reg_key(frmr->mr, ibmr->remap_count++);
        frmr->fr_reg = true;

        memset(&reg_wr, 0, sizeof(reg_wr));
        reg_wr.wr.wr_id = (unsigned long)(void *)ibmr;
        reg_wr.wr.opcode = IB_WR_REG_MR;
        reg_wr.wr.num_sge = 0;
        reg_wr.mr = frmr->mr;
        reg_wr.key = frmr->mr->rkey;
        reg_wr.access = IB_ACCESS_LOCAL_WRITE |
                        IB_ACCESS_REMOTE_READ |
                        IB_ACCESS_REMOTE_WRITE;
        reg_wr.wr.send_flags = IB_SEND_SIGNALED;

        ret = ib_post_send(ibmr->ic->i_cm_id->qp, &reg_wr.wr, NULL);
        if (unlikely(ret)) {
                /* Failure here can be because of -ENOMEM as well */
                rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);

                if (printk_ratelimit())
                        pr_warn("RDS/IB: %s returned error(%d)\n",
                                __func__, ret);
                goto out_inc;
        }

        /* Wait for the registration to complete in order to prevent an invalid
         * access error resulting from a race between the memory region already
         * being accessed while registration is still pending.
         */
        wait_event(frmr->fr_reg_done, !frmr->fr_reg);

        return ret;

out_inc:
        atomic_inc(&ibmr->ic->i_fastreg_wrs);
        return ret;
}

static int rds_ib_map_frmr(struct rds_ib_device *rds_ibdev,
                           struct rds_ib_mr_pool *pool,
                           struct rds_ib_mr *ibmr,
                           struct scatterlist *sg, unsigned int sg_len)
{
        struct ib_device *dev = rds_ibdev->dev;
        struct rds_ib_frmr *frmr = &ibmr->u.frmr;
        int i;
        u32 len;
        int ret = 0;

        /* We want to teardown old ibmr values here and fill it up with
         * new sg values
         */
        rds_ib_teardown_mr(ibmr);

        ibmr->sg = sg;
        ibmr->sg_len = sg_len;
        ibmr->sg_dma_len = 0;
        frmr->sg_byte_len = 0;
        WARN_ON(ibmr->sg_dma_len);
        ibmr->sg_dma_len = ib_dma_map_sg(dev, ibmr->sg, ibmr->sg_len,
                                         DMA_BIDIRECTIONAL);
        if (unlikely(!ibmr->sg_dma_len)) {
                pr_warn("RDS/IB: %s failed!\n", __func__);
                return -EBUSY;
        }

        frmr->sg_byte_len = 0;
        frmr->dma_npages = 0;
        len = 0;

        ret = -EINVAL;
        for (i = 0; i < ibmr->sg_dma_len; ++i) {
                unsigned int dma_len = sg_dma_len(&ibmr->sg[i]);
                u64 dma_addr = sg_dma_address(&ibmr->sg[i]);

                frmr->sg_byte_len += dma_len;
                if (dma_addr & ~PAGE_MASK) {
                        if (i > 0)
                                goto out_unmap;
                        else
                                ++frmr->dma_npages;
                }

                if ((dma_addr + dma_len) & ~PAGE_MASK) {
                        if (i < ibmr->sg_dma_len - 1)
                                goto out_unmap;
                        else
                                ++frmr->dma_npages;
                }

                len += dma_len;
        }
        frmr->dma_npages += len >> PAGE_SHIFT;

        if (frmr->dma_npages > ibmr->pool->max_pages) {
                ret = -EMSGSIZE;
                goto out_unmap;
        }

        ret = rds_ib_post_reg_frmr(ibmr);
        if (ret)
                goto out_unmap;

        if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
                rds_ib_stats_inc(s_ib_rdma_mr_8k_used);
        else
                rds_ib_stats_inc(s_ib_rdma_mr_1m_used);

        return ret;

out_unmap:
        ib_dma_unmap_sg(rds_ibdev->dev, ibmr->sg, ibmr->sg_len,
                        DMA_BIDIRECTIONAL);
        ibmr->sg_dma_len = 0;
        return ret;
}

static int rds_ib_post_inv(struct rds_ib_mr *ibmr)
{
        struct ib_send_wr *s_wr;
        struct rds_ib_frmr *frmr = &ibmr->u.frmr;
        struct rdma_cm_id *i_cm_id = ibmr->ic->i_cm_id;
        int ret = -EINVAL;

        if (!i_cm_id || !i_cm_id->qp || !frmr->mr)
                goto out;

        if (frmr->fr_state != FRMR_IS_INUSE)
                goto out;

        while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) {
                atomic_inc(&ibmr->ic->i_fastreg_wrs);
                cpu_relax();
        }

        frmr->fr_inv = true;
        s_wr = &frmr->fr_wr;

        memset(s_wr, 0, sizeof(*s_wr));
        s_wr->wr_id = (unsigned long)(void *)ibmr;
        s_wr->opcode = IB_WR_LOCAL_INV;
        s_wr->ex.invalidate_rkey = frmr->mr->rkey;
        s_wr->send_flags = IB_SEND_SIGNALED;

        ret = ib_post_send(i_cm_id->qp, s_wr, NULL);
        if (unlikely(ret)) {
                rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);
                frmr->fr_inv = false;
                /* enforce order of frmr->fr_inv update
                 * before incrementing i_fastreg_wrs
                 */
                smp_mb__before_atomic();
                atomic_inc(&ibmr->ic->i_fastreg_wrs);
                pr_err("RDS/IB: %s returned error(%d)\n", __func__, ret);
                goto out;
        }

        /* Wait for the FRMR_IS_FREE (or FRMR_IS_STALE) transition in order to
         * 1) avoid a silly bouncing between "clean_list" and "drop_list"
         *    triggered by function "rds_ib_reg_frmr" as it is releases frmr
         *    regions whose state is not "FRMR_IS_FREE" right away.
         * 2) prevents an invalid access error in a race
         *    from a pending "IB_WR_LOCAL_INV" operation
         *    with a teardown ("dma_unmap_sg", "put_page")
         *    and de-registration ("ib_dereg_mr") of the corresponding
         *    memory region.
         */
        wait_event(frmr->fr_inv_done, frmr->fr_state != FRMR_IS_INUSE);

out:
        return ret;
}

void rds_ib_mr_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
{
        struct rds_ib_mr *ibmr = (void *)(unsigned long)wc->wr_id;
        struct rds_ib_frmr *frmr = &ibmr->u.frmr;

        if (wc->status != IB_WC_SUCCESS) {
                rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_STALE);
                if (rds_conn_up(ic->conn))
                        rds_ib_conn_error(ic->conn,
                                          "frmr completion <%pI4,%pI4> status %u(%s), vendor_err 0x%x, disconnecting and reconnecting\n",
                                          &ic->conn->c_laddr,
                                          &ic->conn->c_faddr,
                                          wc->status,
                                          ib_wc_status_msg(wc->status),
                                          wc->vendor_err);
        }

        if (frmr->fr_inv) {
                rds_transition_frwr_state(ibmr, FRMR_IS_INUSE, FRMR_IS_FREE);
                frmr->fr_inv = false;
                wake_up(&frmr->fr_inv_done);
        }

        if (frmr->fr_reg) {
                frmr->fr_reg = false;
                wake_up(&frmr->fr_reg_done);
        }

        /* enforce order of frmr->{fr_reg,fr_inv} update
         * before incrementing i_fastreg_wrs
         */
        smp_mb__before_atomic();
        atomic_inc(&ic->i_fastreg_wrs);
}

void rds_ib_unreg_frmr(struct list_head *list, unsigned int *nfreed,
                       unsigned long *unpinned, unsigned int goal)
{
        struct rds_ib_mr *ibmr, *next;
        struct rds_ib_frmr *frmr;
        int ret = 0, ret2;
        unsigned int freed = *nfreed;

        /* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
        list_for_each_entry(ibmr, list, unmap_list) {
                if (ibmr->sg_dma_len) {
                        ret2 = rds_ib_post_inv(ibmr);
                        if (ret2 && !ret)
                                ret = ret2;
                }
        }

        if (ret)
                pr_warn("RDS/IB: %s failed (err=%d)\n", __func__, ret);

        /* Now we can destroy the DMA mapping and unpin any pages */
        list_for_each_entry_safe(ibmr, next, list, unmap_list) {
                *unpinned += ibmr->sg_len;
                frmr = &ibmr->u.frmr;
                __rds_ib_teardown_mr(ibmr);
                if (freed < goal || frmr->fr_state == FRMR_IS_STALE) {
                        /* Don't de-allocate if the MR is not free yet */
                        if (frmr->fr_state == FRMR_IS_INUSE)
                                continue;

                        if (ibmr->pool->pool_type == RDS_IB_MR_8K_POOL)
                                rds_ib_stats_inc(s_ib_rdma_mr_8k_free);
                        else
                                rds_ib_stats_inc(s_ib_rdma_mr_1m_free);
                        list_del(&ibmr->unmap_list);
                        if (frmr->mr)
                                ib_dereg_mr(frmr->mr);
                        kfree(ibmr);
                        freed++;
                }
        }
        *nfreed = freed;
}

struct rds_ib_mr *rds_ib_reg_frmr(struct rds_ib_device *rds_ibdev,
                                  struct rds_ib_connection *ic,
                                  struct scatterlist *sg,
                                  unsigned long nents, u32 *key)
{
        struct rds_ib_mr *ibmr = NULL;
        struct rds_ib_frmr *frmr;
        int ret;

        if (!ic) {
                /* TODO: Add FRWR support for RDS_GET_MR using proxy qp*/
                return ERR_PTR(-EOPNOTSUPP);
        }

        do {
                if (ibmr)
                        rds_ib_free_frmr(ibmr, true);
                ibmr = rds_ib_alloc_frmr(rds_ibdev, nents);
                if (IS_ERR(ibmr))
                        return ibmr;
                frmr = &ibmr->u.frmr;
        } while (frmr->fr_state != FRMR_IS_FREE);

        ibmr->ic = ic;
        ibmr->device = rds_ibdev;
        ret = rds_ib_map_frmr(rds_ibdev, ibmr->pool, ibmr, sg, nents);
        if (ret == 0) {
                *key = frmr->mr->rkey;
        } else {
                rds_ib_free_frmr(ibmr, false);
                ibmr = ERR_PTR(ret);
        }

        return ibmr;
}

void rds_ib_free_frmr_list(struct rds_ib_mr *ibmr)
{
        struct rds_ib_mr_pool *pool = ibmr->pool;
        struct rds_ib_frmr *frmr = &ibmr->u.frmr;

        if (frmr->fr_state == FRMR_IS_STALE)
                llist_add(&ibmr->llnode, &pool->drop_list);
        else
                llist_add(&ibmr->llnode, &pool->free_list);
}