// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
 * Copyright (c) 2024 Oracle.  All rights reserved.
 */

/* #include <linux/module.h>
#include <linux/slab.h> */
#include <linux/xarray.h>
#include <linux/types.h>
#include <linux/kref.h>
#include <linux/completion.h>

#include <linux/sunrpc/svc_rdma.h>
#include <linux/sunrpc/rdma_rn.h>

#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>

/* Per-ib_device private data for rpcrdma */
struct rpcrdma_device {
        struct kref             rd_kref;
        unsigned long           rd_flags;
        struct ib_device        *rd_device;
        struct xarray           rd_xa;
        struct completion       rd_done;
};

#define RPCRDMA_RD_F_REMOVING   (0)

static struct ib_client rpcrdma_ib_client;

/*
 * Listeners have no associated device, so we never register them.
 * Note that ib_get_client_data() does not check if @device is
 * NULL for us.
 */
static struct rpcrdma_device *rpcrdma_get_client_data(struct ib_device *device)
{
        if (!device)
                return NULL;
        return ib_get_client_data(device, &rpcrdma_ib_client);
}

/**
 * rpcrdma_rn_register - register to get device removal notifications
 * @device: device to monitor
 * @rn: notification object that wishes to be notified
 * @done: callback to notify caller of device removal
 *
 * Returns zero on success. The callback in rn_done is guaranteed
 * to be invoked when the device is removed, unless this notification
 * is unregistered first.
 *
 * On failure, a negative errno is returned.
 */
int rpcrdma_rn_register(struct ib_device *device,
                        struct rpcrdma_notification *rn,
                        void (*done)(struct rpcrdma_notification *rn))
{
        struct rpcrdma_device *rd = rpcrdma_get_client_data(device);

        if (!rd || test_bit(RPCRDMA_RD_F_REMOVING, &rd->rd_flags))
                return -ENETUNREACH;

        if (xa_alloc(&rd->rd_xa, &rn->rn_index, rn, xa_limit_32b, GFP_KERNEL) < 0)
                return -ENOMEM;
        kref_get(&rd->rd_kref);
        rn->rn_done = done;
        trace_rpcrdma_client_register(device, rn);
        return 0;
}

static void rpcrdma_rn_release(struct kref *kref)
{
        struct rpcrdma_device *rd = container_of(kref, struct rpcrdma_device,
                                                 rd_kref);

        trace_rpcrdma_client_completion(rd->rd_device);
        complete(&rd->rd_done);
}

/**
 * rpcrdma_rn_unregister - stop device removal notifications
 * @device: monitored device
 * @rn: notification object that no longer wishes to be notified
 */
void rpcrdma_rn_unregister(struct ib_device *device,
                           struct rpcrdma_notification *rn)
{
        struct rpcrdma_device *rd = rpcrdma_get_client_data(device);

        if (!rd)
                return;

        trace_rpcrdma_client_unregister(device, rn);
        xa_erase(&rd->rd_xa, rn->rn_index);
        kref_put(&rd->rd_kref, rpcrdma_rn_release);
}

/**
 * rpcrdma_add_one - ib_client device insertion callback
 * @device: device about to be inserted
 *
 * Returns zero on success. xprtrdma private data has been allocated
 * for this device. On failure, a negative errno is returned.
 */
static int rpcrdma_add_one(struct ib_device *device)
{
        struct rpcrdma_device *rd;

        rd = kzalloc_obj(*rd);
        if (!rd)
                return -ENOMEM;

        kref_init(&rd->rd_kref);
        xa_init_flags(&rd->rd_xa, XA_FLAGS_ALLOC);
        rd->rd_device = device;
        init_completion(&rd->rd_done);
        ib_set_client_data(device, &rpcrdma_ib_client, rd);

        trace_rpcrdma_client_add_one(device);
        return 0;
}

/**
 * rpcrdma_remove_one - ib_client device removal callback
 * @device: device about to be removed
 * @client_data: this module's private per-device data
 *
 * Upon return, all transports associated with @device have divested
 * themselves from IB hardware resources.
 */
static void rpcrdma_remove_one(struct ib_device *device,
                               void *client_data)
{
        struct rpcrdma_device *rd = client_data;
        struct rpcrdma_notification *rn;
        unsigned long index;

        trace_rpcrdma_client_remove_one(device);

        set_bit(RPCRDMA_RD_F_REMOVING, &rd->rd_flags);
        xa_for_each(&rd->rd_xa, index, rn)
                rn->rn_done(rn);

        /*
         * Wait only if there are still outstanding notification
         * registrants for this device.
         */
        if (!refcount_dec_and_test(&rd->rd_kref.refcount)) {
                trace_rpcrdma_client_wait_on(device);
                wait_for_completion(&rd->rd_done);
        }

        trace_rpcrdma_client_remove_one_done(device);
        xa_destroy(&rd->rd_xa);
        kfree(rd);
}

static struct ib_client rpcrdma_ib_client = {
        .name           = "rpcrdma",
        .add            = rpcrdma_add_one,
        .remove         = rpcrdma_remove_one,
};

/**
 * rpcrdma_ib_client_unregister - unregister ib_client for xprtrdma
 *
 * cel: watch for orphaned rpcrdma_device objects on module unload
 */
void rpcrdma_ib_client_unregister(void)
{
        ib_unregister_client(&rpcrdma_ib_client);
}

/**
 * rpcrdma_ib_client_register - register ib_client for rpcrdma
 *
 * Returns zero on success, or a negative errno.
 */
int rpcrdma_ib_client_register(void)
{
        return ib_register_client(&rpcrdma_ib_client);
}