/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
 * vim:expandtab:shiftwidth=8:tabstop=8:
 *
 *  Copyright (C) 2002 Cluster File Systems, Inc.
 *
 *   This file is part of Lustre, http://www.lustre.org.
 *
 *   Lustre is free software; you can redistribute it and/or
 *   modify it under the terms of version 2 of the GNU General Public
 *   License as published by the Free Software Foundation.
 *
 *   Lustre is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with Lustre; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#define DEBUG_SUBSYSTEM S_RPC

#include <linux/obd_support.h>
#include <linux/obd_class.h>
#include <linux/lustre_net.h>

extern int request_in_callback(ptl_event_t *ev);

static int ptlrpc_check_event(struct ptlrpc_service *svc,
                              struct ptlrpc_thread *thread, ptl_event_t *event)
{
        int rc;
        ENTRY;

        spin_lock(&svc->srv_lock);

        if (thread->t_flags & SVC_STOPPING)
                GOTO(out, rc = 1);

        LASSERT ((thread->t_flags & SVC_EVENT) == 0);
        LASSERT (ptl_is_valid_handle (&svc->srv_eq_h));

        rc = PtlEQGet(svc->srv_eq_h, event);
        switch (rc)
        {
        case PTL_OK:
                thread->t_flags |= SVC_EVENT;
                GOTO(out, rc = 1);
                
        case PTL_EQ_EMPTY:
                GOTO(out, rc = 0);
                
        default:
                CERROR("BUG: PtlEQGet returned %d\n", rc);
                LBUG();
        }
 out:
        spin_unlock(&svc->srv_lock);
        return rc;
}

struct ptlrpc_service *
ptlrpc_init_svc(__u32 nevents, __u32 nbufs,
                __u32 bufsize, __u32 max_req_size,
                int req_portal, int rep_portal,
                obd_uuid_t uuid, svc_handler_t handler, char *name)
{
        int err;
        int rc, i;
        struct ptlrpc_service *service;
        ENTRY;

        OBD_ALLOC(service, sizeof(*service));
        if (!service)
                RETURN(NULL);

        service->srv_name = name;
        spin_lock_init(&service->srv_lock);
        INIT_LIST_HEAD(&service->srv_threads);
        init_waitqueue_head(&service->srv_waitq);

        service->srv_max_req_size = max_req_size;
        service->srv_buf_size = bufsize;
        INIT_LIST_HEAD(&service->srv_rqbds);
        service->srv_nrqbds = 0;
        atomic_set(&service->srv_nrqbds_receiving, 0);

        service->srv_rep_portal = rep_portal;
        service->srv_req_portal = req_portal;
        service->srv_handler = handler;

        err = kportal_uuid_to_peer(uuid, &service->srv_self);
        if (err) {
                CERROR("%s: cannot get peer for uuid '%s'\n", name, uuid);
                OBD_FREE(service, sizeof(*service));
                RETURN(NULL);
        }

        rc = PtlEQAlloc(service->srv_self.peer_ni, nevents,
                        request_in_callback, &(service->srv_eq_h));

        if (rc != PTL_OK) {
                CERROR("%s: PtlEQAlloc failed: %d\n", name, rc);
                OBD_FREE(service, sizeof(*service));
                RETURN(NULL);
        }

        for (i = 0; i < nbufs; i++) {
                struct ptlrpc_request_buffer_desc *rqbd;

                OBD_ALLOC(rqbd, sizeof(*rqbd));
                if (rqbd == NULL)
                        GOTO(failed, NULL);

                rqbd->rqbd_service = service;
                ptl_set_inv_handle(&rqbd->rqbd_me_h);
                atomic_set(&rqbd->rqbd_refcount, 0);
                OBD_ALLOC(rqbd->rqbd_buffer, service->srv_buf_size);
                if (rqbd->rqbd_buffer == NULL) {
                        OBD_FREE(rqbd, sizeof(*rqbd));
                        GOTO(failed, NULL);
                }
                list_add(&rqbd->rqbd_list, &service->srv_rqbds);
                service->srv_nrqbds++;

                ptlrpc_link_svc_me(rqbd);
        }

        CDEBUG(D_NET, "Starting service listening on portal %d (eq: %p)\n",
               service->srv_req_portal, service->srv_eq_h.handle_idx);

        RETURN(service);
failed:
        ptlrpc_unregister_service(service);
        return NULL;
}

static int handle_incoming_request(struct obd_device *obddev,
                                   struct ptlrpc_service *svc,
                                   ptl_event_t *event,
                                   struct ptlrpc_request *request)
{
        struct ptlrpc_request_buffer_desc *rqbd = event->mem_desc.user_ptr;
        int rc;

        /* FIXME: If we move to an event-driven model, we should put the request
         * on the stack of mds_handle instead. */

        LASSERT (atomic_read (&rqbd->rqbd_refcount) > 0);
        LASSERT ((event->mem_desc.options & PTL_MD_IOV) == 0);
        LASSERT (rqbd->rqbd_service == svc);
        LASSERT (rqbd->rqbd_buffer == event->mem_desc.start);
        LASSERT (event->offset + event->mlength <= svc->srv_buf_size);

        memset(request, 0, sizeof(*request));
        request->rq_svc = svc;
        request->rq_obd = obddev;
        request->rq_xid = event->match_bits;
        request->rq_reqmsg = event->mem_desc.start + event->offset;
        request->rq_reqlen = event->mlength;

        rc = -EINVAL;

        if (request->rq_reqlen < sizeof(struct lustre_msg)) {
                CERROR("incomplete request (%d): ptl %d from "LPX64" xid "
                       LPD64"\n",
                       request->rq_reqlen, svc->srv_req_portal,
                       event->initiator.nid, request->rq_xid);
                goto out;
        }

        if (NTOH__u32(request->rq_reqmsg->type) != PTL_RPC_MSG_REQUEST) {
                CERROR("wrong packet type received (type=%u)\n",
                       request->rq_reqmsg->type);
                goto out;
        }

        if (request->rq_reqmsg->magic != PTLRPC_MSG_MAGIC) {
                CERROR("wrong lustre_msg magic %d: ptl %d from "LPX64" xid "
                       LPD64"\n",
                       request->rq_reqmsg->magic, svc->srv_req_portal,
                       event->initiator.nid, request->rq_xid);
                goto out;
        }

        if (request->rq_reqmsg->version != PTLRPC_MSG_VERSION) {
                CERROR("wrong lustre_msg version %d: ptl %d from "LPX64" xid "
                       LPD64"\n",
                       request->rq_reqmsg->version, svc->srv_req_portal,
                       event->initiator.nid, request->rq_xid);
                goto out;
        }

        CDEBUG(D_NET, "got req "LPD64" (md: %p + %d)\n", request->rq_xid,
               event->mem_desc.start, event->offset);

        request->rq_peer.peer_nid = event->initiator.nid;
        /* FIXME: this NI should be the incoming NI.
         * We don't know how to find that from here. */
        request->rq_peer.peer_ni = svc->srv_self.peer_ni;

        request->rq_export = class_conn2export((struct lustre_handle *)
                                               request->rq_reqmsg);

        if (request->rq_export) {
                request->rq_connection = request->rq_export->exp_connection;
                ptlrpc_connection_addref(request->rq_connection);
        } else {
                /* create a (hopefully temporary) connection that will be used
                 * to send the reply if this call doesn't create an export.
                 * XXX revisit this when we revamp ptlrpc */
                request->rq_connection =
                        ptlrpc_get_connection(&request->rq_peer, NULL);
        }

        rc = svc->srv_handler(request);
        ptlrpc_put_connection(request->rq_connection);

 out:
        if (atomic_dec_and_test (&rqbd->rqbd_refcount)) /* last reference? */
                ptlrpc_link_svc_me (rqbd);

        return rc;
}

static int ptlrpc_main(void *arg)
{
        struct ptlrpc_svc_data *data = (struct ptlrpc_svc_data *)arg;
        struct obd_device *obddev = data->dev;
        struct ptlrpc_service *svc = data->svc;
        struct ptlrpc_thread *thread = data->thread;
        struct ptlrpc_request *request;
        ptl_event_t *event;
        int rc = 0;

        ENTRY;

        lock_kernel();
        daemonize();
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,0)
        sigfillset(&current->blocked);
        recalc_sigpending();
#else
        spin_lock_irq(&current->sigmask_lock);
        sigfillset(&current->blocked);
        recalc_sigpending(current);
        spin_unlock_irq(&current->sigmask_lock);
#endif

        strcpy(current->comm, data->name);
        unlock_kernel();

        OBD_ALLOC(event, sizeof(*event));
        if (!event)
                GOTO(out, rc = -ENOMEM);
        OBD_ALLOC(request, sizeof(*request));
        if (!request)
                GOTO(out_event, rc = -ENOMEM);

        /* Record that the thread is running */
        thread->t_flags = SVC_RUNNING;
        wake_up(&thread->t_ctl_waitq);

        /* XXX maintain a list of all managed devices: insert here */

        /* And now, loop forever on requests */
        while (1) {
                wait_event(svc->srv_waitq,
                           ptlrpc_check_event(svc, thread, event));

                if (thread->t_flags & SVC_STOPPING) {
                        spin_lock(&svc->srv_lock);
                        thread->t_flags &= ~SVC_STOPPING;
                        spin_unlock(&svc->srv_lock);

                        EXIT;
                        break;
                }

                if (thread->t_flags & SVC_EVENT) {
                        spin_lock(&svc->srv_lock);
                        thread->t_flags &= ~SVC_EVENT;
                        spin_unlock(&svc->srv_lock);

                        rc = handle_incoming_request(obddev, svc, event,
                                                     request);
                        continue;
                }

                CERROR("unknown break in service");
                LBUG();
                EXIT;
                break;
        }

        OBD_FREE(request, sizeof(*request));
out_event:
        OBD_FREE(event, sizeof(*event));
out:
        thread->t_flags = SVC_STOPPED;
        wake_up(&thread->t_ctl_waitq);

        CDEBUG(D_NET, "service thread exiting, process %d: rc = %d\n",
               current->pid, rc);
        return rc;
}

static void ptlrpc_stop_thread(struct ptlrpc_service *svc,
                               struct ptlrpc_thread *thread)
{
        spin_lock(&svc->srv_lock);
        thread->t_flags = SVC_STOPPING;
        spin_unlock(&svc->srv_lock);

        wake_up(&svc->srv_waitq);
        wait_event(thread->t_ctl_waitq, (thread->t_flags & SVC_STOPPED));
}

void ptlrpc_stop_all_threads(struct ptlrpc_service *svc)
{
        spin_lock(&svc->srv_lock);
        while (!list_empty(&svc->srv_threads)) {
                struct ptlrpc_thread *thread;
                thread = list_entry(svc->srv_threads.next, struct ptlrpc_thread,
                                    t_link);
                spin_unlock(&svc->srv_lock);
                ptlrpc_stop_thread(svc, thread);
                spin_lock(&svc->srv_lock);
                list_del(&thread->t_link);
                OBD_FREE(thread, sizeof(*thread));
        }
        spin_unlock(&svc->srv_lock);
}

int ptlrpc_start_thread(struct obd_device *dev, struct ptlrpc_service *svc,
                        char *name)
{
        struct ptlrpc_svc_data d;
        struct ptlrpc_thread *thread;
        int rc;
        ENTRY;

        OBD_ALLOC(thread, sizeof(*thread));
        if (thread == NULL) {
                LBUG();
                RETURN(-ENOMEM);
        }
        init_waitqueue_head(&thread->t_ctl_waitq);

        d.dev = dev;
        d.svc = svc;
        d.name = name;
        d.thread = thread;

        spin_lock(&svc->srv_lock);
        list_add(&thread->t_link, &svc->srv_threads);
        spin_unlock(&svc->srv_lock);

        /* XXX should we really be cloning open file handles here? */
        rc = kernel_thread(ptlrpc_main, (void *) &d,
                           CLONE_VM | CLONE_FS | CLONE_FILES);
        if (rc < 0) {
                CERROR("cannot start thread\n");
                OBD_FREE(thread, sizeof(*thread));
                RETURN(rc);
        }
        wait_event(thread->t_ctl_waitq, thread->t_flags & SVC_RUNNING);

        RETURN(0);
}

int ptlrpc_unregister_service(struct ptlrpc_service *service)
{
        int rc;

        LASSERT (list_empty (&service->srv_threads));

        /* XXX We could reply (with failure) to all buffered requests
         * _after_ unlinking _all_ the request buffers, but _before_
         * freeing them.
         */

        while (!list_empty (&service->srv_rqbds)) {
                struct ptlrpc_request_buffer_desc *rqbd =
                        list_entry (service->srv_rqbds.next,
                                    struct ptlrpc_request_buffer_desc,
                                    rqbd_list);

                list_del (&rqbd->rqbd_list);

                LASSERT (atomic_read (&rqbd->rqbd_refcount) > 0);
                /* refcount could be anything; it's possible for the
                 * buffers to continued to get filled after all the server
                 * threads exited.  But we know they _have_ exited.
                 */

                (void) PtlMEUnlink(rqbd->rqbd_me_h);
                /* The callback handler could have unlinked this ME already
                 * (we're racing with her) but it's safe to ensure it _has_
                 * been unlinked.
                 */

                OBD_FREE (rqbd->rqbd_buffer, service->srv_buf_size);
                OBD_FREE (rqbd, sizeof (*rqbd));
                service->srv_nrqbds--;
        }

        LASSERT (service->srv_nrqbds == 0);

        rc = PtlEQFree(service->srv_eq_h);
        if (rc)
                CERROR("PtlEQFree failed: %d\n", rc);

        OBD_FREE(service, sizeof(*service));
        if (rc)
                LBUG();
        return rc;
}