/*
* Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
* Copyright (c) 2015 System Fabric Works, Inc. 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 <linux/skbuff.h>
#include "rxe.h"
#include "rxe_loc.h"
#include "rxe_queue.h"
#include "rxe_task.h"
enum comp_state {
COMPST_GET_ACK,
COMPST_GET_WQE,
COMPST_COMP_WQE,
COMPST_COMP_ACK,
COMPST_CHECK_PSN,
COMPST_CHECK_ACK,
COMPST_READ,
COMPST_ATOMIC,
COMPST_WRITE_SEND,
COMPST_UPDATE_COMP,
COMPST_ERROR_RETRY,
COMPST_RNR_RETRY,
COMPST_ERROR,
COMPST_EXIT, /* We have an issue, and we want to rerun the completer */
COMPST_DONE, /* The completer finished successflly */
};
static char *comp_state_name[] = {
[COMPST_GET_ACK] = "GET ACK",
[COMPST_GET_WQE] = "GET WQE",
[COMPST_COMP_WQE] = "COMP WQE",
[COMPST_COMP_ACK] = "COMP ACK",
[COMPST_CHECK_PSN] = "CHECK PSN",
[COMPST_CHECK_ACK] = "CHECK ACK",
[COMPST_READ] = "READ",
[COMPST_ATOMIC] = "ATOMIC",
[COMPST_WRITE_SEND] = "WRITE/SEND",
[COMPST_UPDATE_COMP] = "UPDATE COMP",
[COMPST_ERROR_RETRY] = "ERROR RETRY",
[COMPST_RNR_RETRY] = "RNR RETRY",
[COMPST_ERROR] = "ERROR",
[COMPST_EXIT] = "EXIT",
[COMPST_DONE] = "DONE",
};
static unsigned long rnrnak_usec[32] = {
[IB_RNR_TIMER_655_36] = 655360,
[IB_RNR_TIMER_000_01] = 10,
[IB_RNR_TIMER_000_02] = 20,
[IB_RNR_TIMER_000_03] = 30,
[IB_RNR_TIMER_000_04] = 40,
[IB_RNR_TIMER_000_06] = 60,
[IB_RNR_TIMER_000_08] = 80,
[IB_RNR_TIMER_000_12] = 120,
[IB_RNR_TIMER_000_16] = 160,
[IB_RNR_TIMER_000_24] = 240,
[IB_RNR_TIMER_000_32] = 320,
[IB_RNR_TIMER_000_48] = 480,
[IB_RNR_TIMER_000_64] = 640,
[IB_RNR_TIMER_000_96] = 960,
[IB_RNR_TIMER_001_28] = 1280,
[IB_RNR_TIMER_001_92] = 1920,
[IB_RNR_TIMER_002_56] = 2560,
[IB_RNR_TIMER_003_84] = 3840,
[IB_RNR_TIMER_005_12] = 5120,
[IB_RNR_TIMER_007_68] = 7680,
[IB_RNR_TIMER_010_24] = 10240,
[IB_RNR_TIMER_015_36] = 15360,
[IB_RNR_TIMER_020_48] = 20480,
[IB_RNR_TIMER_030_72] = 30720,
[IB_RNR_TIMER_040_96] = 40960,
[IB_RNR_TIMER_061_44] = 61410,
[IB_RNR_TIMER_081_92] = 81920,
[IB_RNR_TIMER_122_88] = 122880,
[IB_RNR_TIMER_163_84] = 163840,
[IB_RNR_TIMER_245_76] = 245760,
[IB_RNR_TIMER_327_68] = 327680,
[IB_RNR_TIMER_491_52] = 491520,
};
static inline unsigned long rnrnak_jiffies(u8 timeout)
{
return max_t(unsigned long,
usecs_to_jiffies(rnrnak_usec[timeout]), 1);
}
static enum ib_wc_opcode wr_to_wc_opcode(enum ib_wr_opcode opcode)
{
switch (opcode) {
case IB_WR_RDMA_WRITE: return IB_WC_RDMA_WRITE;
case IB_WR_RDMA_WRITE_WITH_IMM: return IB_WC_RDMA_WRITE;
case IB_WR_SEND: return IB_WC_SEND;
case IB_WR_SEND_WITH_IMM: return IB_WC_SEND;
case IB_WR_RDMA_READ: return IB_WC_RDMA_READ;
case IB_WR_ATOMIC_CMP_AND_SWP: return IB_WC_COMP_SWAP;
case IB_WR_ATOMIC_FETCH_AND_ADD: return IB_WC_FETCH_ADD;
case IB_WR_LSO: return IB_WC_LSO;
case IB_WR_SEND_WITH_INV: return IB_WC_SEND;
case IB_WR_RDMA_READ_WITH_INV: return IB_WC_RDMA_READ;
case IB_WR_LOCAL_INV: return IB_WC_LOCAL_INV;
case IB_WR_REG_MR: return IB_WC_REG_MR;
default:
return 0xff;
}
}
void retransmit_timer(unsigned long data)
{
struct rxe_qp *qp = (struct rxe_qp *)data;
if (qp->valid) {
qp->comp.timeout = 1;
rxe_run_task(&qp->comp.task, 1);
}
}
void rxe_comp_queue_pkt(struct rxe_dev *rxe, struct rxe_qp *qp,
struct sk_buff *skb)
{
int must_sched;
skb_queue_tail(&qp->resp_pkts, skb);
must_sched = skb_queue_len(&qp->resp_pkts) > 1;
rxe_run_task(&qp->comp.task, must_sched);
}
static inline enum comp_state get_wqe(struct rxe_qp *qp,
struct rxe_pkt_info *pkt,
struct rxe_send_wqe **wqe_p)
{
struct rxe_send_wqe *wqe;
/* we come here whether or not we found a response packet to see if
* there are any posted WQEs
*/
wqe = queue_head(qp->sq.queue);
*wqe_p = wqe;
/* no WQE or requester has not started it yet */
if (!wqe || wqe->state == wqe_state_posted)
return pkt ? COMPST_DONE : COMPST_EXIT;
/* WQE does not require an ack */
if (wqe->state == wqe_state_done)
return COMPST_COMP_WQE;
/* WQE caused an error */
if (wqe->state == wqe_state_error)
return COMPST_ERROR;
/* we have a WQE, if we also have an ack check its PSN */
return pkt ? COMPST_CHECK_PSN : COMPST_EXIT;
}
static inline void reset_retry_counters(struct rxe_qp *qp)
{
qp->comp.retry_cnt = qp->attr.retry_cnt;
qp->comp.rnr_retry = qp->attr.rnr_retry;
}
static inline enum comp_state check_psn(struct rxe_qp *qp,
struct rxe_pkt_info *pkt,
struct rxe_send_wqe *wqe)
{
s32 diff;
/* check to see if response is past the oldest WQE. if it is, complete
* send/write or error read/atomic
*/
diff = psn_compare(pkt->psn, wqe->last_psn);
if (diff > 0) {
if (wqe->state == wqe_state_pending) {
if (wqe->mask & WR_ATOMIC_OR_READ_MASK)
return COMPST_ERROR_RETRY;
reset_retry_counters(qp);
return COMPST_COMP_WQE;
} else {
return COMPST_DONE;
}
}
/* compare response packet to expected response */
diff = psn_compare(pkt->psn, qp->comp.psn);
if (diff < 0) {
/* response is most likely a retried packet if it matches an
* uncompleted WQE go complete it else ignore it
*/
if (pkt->psn == wqe->last_psn)
return COMPST_COMP_ACK;
else
return COMPST_DONE;
} else if ((diff > 0) && (wqe->mask & WR_ATOMIC_OR_READ_MASK)) {
return COMPST_DONE;
} else {
return COMPST_CHECK_ACK;
}
}
static inline enum comp_state check_ack(struct rxe_qp *qp,
struct rxe_pkt_info *pkt,
struct rxe_send_wqe *wqe)
{
unsigned int mask = pkt->mask;
u8 syn;
/* Check the sequence only */
switch (qp->comp.opcode) {
case -1:
/* Will catch all *_ONLY cases. */
if (!(mask & RXE_START_MASK))
return COMPST_ERROR;
break;
case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
if (pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE &&
pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) {
return COMPST_ERROR;
}
break;
default:
WARN_ON_ONCE(1);
}
/* Check operation validity. */
switch (pkt->opcode) {
case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
syn = aeth_syn(pkt);
if ((syn & AETH_TYPE_MASK) != AETH_ACK)
return COMPST_ERROR;
/* Fall through (IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE
* doesn't have an AETH)
*/
case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
if (wqe->wr.opcode != IB_WR_RDMA_READ &&
wqe->wr.opcode != IB_WR_RDMA_READ_WITH_INV) {
return COMPST_ERROR;
}
reset_retry_counters(qp);
return COMPST_READ;
case IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE:
syn = aeth_syn(pkt);
if ((syn & AETH_TYPE_MASK) != AETH_ACK)
return COMPST_ERROR;
if (wqe->wr.opcode != IB_WR_ATOMIC_CMP_AND_SWP &&
wqe->wr.opcode != IB_WR_ATOMIC_FETCH_AND_ADD)
return COMPST_ERROR;
reset_retry_counters(qp);
return COMPST_ATOMIC;
case IB_OPCODE_RC_ACKNOWLEDGE:
syn = aeth_syn(pkt);
switch (syn & AETH_TYPE_MASK) {
case AETH_ACK:
reset_retry_counters(qp);
return COMPST_WRITE_SEND;
case AETH_RNR_NAK:
return COMPST_RNR_RETRY;
case AETH_NAK:
switch (syn) {
case AETH_NAK_PSN_SEQ_ERROR:
/* a nak implicitly acks all packets with psns
* before
*/
if (psn_compare(pkt->psn, qp->comp.psn) > 0) {
qp->comp.psn = pkt->psn;
if (qp->req.wait_psn) {
qp->req.wait_psn = 0;
rxe_run_task(&qp->req.task, 1);
}
}
return COMPST_ERROR_RETRY;
case AETH_NAK_INVALID_REQ:
wqe->status = IB_WC_REM_INV_REQ_ERR;
return COMPST_ERROR;
case AETH_NAK_REM_ACC_ERR:
wqe->status = IB_WC_REM_ACCESS_ERR;
return COMPST_ERROR;
case AETH_NAK_REM_OP_ERR:
wqe->status = IB_WC_REM_OP_ERR;
return COMPST_ERROR;
default:
pr_warn("unexpected nak %x\n", syn);
wqe->status = IB_WC_REM_OP_ERR;
return COMPST_ERROR;
}
default:
return COMPST_ERROR;
}
break;
default:
pr_warn("unexpected opcode\n");
}
return COMPST_ERROR;
}
static inline enum comp_state do_read(struct rxe_qp *qp,
struct rxe_pkt_info *pkt,
struct rxe_send_wqe *wqe)
{
struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
int ret;
ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
&wqe->dma, payload_addr(pkt),
payload_size(pkt), to_mem_obj, NULL);
if (ret)
return COMPST_ERROR;
if (wqe->dma.resid == 0 && (pkt->mask & RXE_END_MASK))
return COMPST_COMP_ACK;
else
return COMPST_UPDATE_COMP;
}
static inline enum comp_state do_atomic(struct rxe_qp *qp,
struct rxe_pkt_info *pkt,
struct rxe_send_wqe *wqe)
{
struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
int ret;
u64 atomic_orig = atmack_orig(pkt);
ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
&wqe->dma, &atomic_orig,
sizeof(u64), to_mem_obj, NULL);
if (ret)
return COMPST_ERROR;
else
return COMPST_COMP_ACK;
}
static void make_send_cqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe,
struct rxe_cqe *cqe)
{
memset(cqe, 0, sizeof(*cqe));
if (!qp->is_user) {
struct ib_wc *wc = &cqe->ibwc;
wc->wr_id = wqe->wr.wr_id;
wc->status = wqe->status;
wc->opcode = wr_to_wc_opcode(wqe->wr.opcode);
if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
wc->wc_flags = IB_WC_WITH_IMM;
wc->byte_len = wqe->dma.length;
wc->qp = &qp->ibqp;
} else {
struct ib_uverbs_wc *uwc = &cqe->uibwc;
uwc->wr_id = wqe->wr.wr_id;
uwc->status = wqe->status;
uwc->opcode = wr_to_wc_opcode(wqe->wr.opcode);
if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
uwc->wc_flags = IB_WC_WITH_IMM;
uwc->byte_len = wqe->dma.length;
uwc->qp_num = qp->ibqp.qp_num;
}
}
/*
* IBA Spec. Section 10.7.3.1 SIGNALED COMPLETIONS
* ---------8<---------8<-------------
* ...Note that if a completion error occurs, a Work Completion
* will always be generated, even if the signaling
* indicator requests an Unsignaled Completion.
* ---------8<---------8<-------------
*/
static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
{
struct rxe_cqe cqe;
if ((qp->sq_sig_type == IB_SIGNAL_ALL_WR) ||
(wqe->wr.send_flags & IB_SEND_SIGNALED) ||
wqe->status != IB_WC_SUCCESS) {
make_send_cqe(qp, wqe, &cqe);
advance_consumer(qp->sq.queue);
rxe_cq_post(qp->scq, &cqe, 0);
} else {
advance_consumer(qp->sq.queue);
}
/*
* we completed something so let req run again
* if it is trying to fence
*/
if (qp->req.wait_fence) {
qp->req.wait_fence = 0;
rxe_run_task(&qp->req.task, 1);
}
}
static inline enum comp_state complete_ack(struct rxe_qp *qp,
struct rxe_pkt_info *pkt,
struct rxe_send_wqe *wqe)
{
unsigned long flags;
if (wqe->has_rd_atomic) {
wqe->has_rd_atomic = 0;
atomic_inc(&qp->req.rd_atomic);
if (qp->req.need_rd_atomic) {
qp->comp.timeout_retry = 0;
qp->req.need_rd_atomic = 0;
rxe_run_task(&qp->req.task, 1);
}
}
if (unlikely(qp->req.state == QP_STATE_DRAIN)) {
/* state_lock used by requester & completer */
spin_lock_irqsave(&qp->state_lock, flags);
if ((qp->req.state == QP_STATE_DRAIN) &&
(qp->comp.psn == qp->req.psn)) {
qp->req.state = QP_STATE_DRAINED;
spin_unlock_irqrestore(&qp->state_lock, flags);
if (qp->ibqp.event_handler) {
struct ib_event ev;
ev.device = qp->ibqp.device;
ev.element.qp = &qp->ibqp;
ev.event = IB_EVENT_SQ_DRAINED;
qp->ibqp.event_handler(&ev,
qp->ibqp.qp_context);
}
} else {
spin_unlock_irqrestore(&qp->state_lock, flags);
}
}
do_complete(qp, wqe);
if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
return COMPST_UPDATE_COMP;
else
return COMPST_DONE;
}
static inline enum comp_state complete_wqe(struct rxe_qp *qp,
struct rxe_pkt_info *pkt,
struct rxe_send_wqe *wqe)
{
qp->comp.opcode = -1;
if (pkt) {
if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
if (qp->req.wait_psn) {
qp->req.wait_psn = 0;
rxe_run_task(&qp->req.task, 1);
}
}
do_complete(qp, wqe);
return COMPST_GET_WQE;
}
static void rxe_drain_resp_pkts(struct rxe_qp *qp, bool notify)
{
struct sk_buff *skb;
struct rxe_send_wqe *wqe;
while ((skb = skb_dequeue(&qp->resp_pkts))) {
rxe_drop_ref(qp);
kfree_skb(skb);
}
while ((wqe = queue_head(qp->sq.queue))) {
if (notify) {
wqe->status = IB_WC_WR_FLUSH_ERR;
do_complete(qp, wqe);
} else {
advance_consumer(qp->sq.queue);
}
}
}
int rxe_completer(void *arg)
{
struct rxe_qp *qp = (struct rxe_qp *)arg;
struct rxe_send_wqe *wqe = wqe;
struct sk_buff *skb = NULL;
struct rxe_pkt_info *pkt = NULL;
enum comp_state state;
rxe_add_ref(qp);
if (!qp->valid || qp->req.state == QP_STATE_ERROR ||
qp->req.state == QP_STATE_RESET) {
rxe_drain_resp_pkts(qp, qp->valid &&
qp->req.state == QP_STATE_ERROR);
goto exit;
}
if (qp->comp.timeout) {
qp->comp.timeout_retry = 1;
qp->comp.timeout = 0;
} else {
qp->comp.timeout_retry = 0;
}
if (qp->req.need_retry)
goto exit;
state = COMPST_GET_ACK;
while (1) {
pr_debug("qp#%d state = %s\n", qp_num(qp),
comp_state_name[state]);
switch (state) {
case COMPST_GET_ACK:
skb = skb_dequeue(&qp->resp_pkts);
if (skb) {
pkt = SKB_TO_PKT(skb);
qp->comp.timeout_retry = 0;
}
state = COMPST_GET_WQE;
break;
case COMPST_GET_WQE:
state = get_wqe(qp, pkt, &wqe);
break;
case COMPST_CHECK_PSN:
state = check_psn(qp, pkt, wqe);
break;
case COMPST_CHECK_ACK:
state = check_ack(qp, pkt, wqe);
break;
case COMPST_READ:
state = do_read(qp, pkt, wqe);
break;
case COMPST_ATOMIC:
state = do_atomic(qp, pkt, wqe);
break;
case COMPST_WRITE_SEND:
if (wqe->state == wqe_state_pending &&
wqe->last_psn == pkt->psn)
state = COMPST_COMP_ACK;
else
state = COMPST_UPDATE_COMP;
break;
case COMPST_COMP_ACK:
state = complete_ack(qp, pkt, wqe);
break;
case COMPST_COMP_WQE:
state = complete_wqe(qp, pkt, wqe);
break;
case COMPST_UPDATE_COMP:
if (pkt->mask & RXE_END_MASK)
qp->comp.opcode = -1;
else
qp->comp.opcode = pkt->opcode;
if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
if (qp->req.wait_psn) {
qp->req.wait_psn = 0;
rxe_run_task(&qp->req.task, 1);
}
state = COMPST_DONE;
break;
case COMPST_DONE:
if (pkt) {
rxe_drop_ref(pkt->qp);
kfree_skb(skb);
skb = NULL;
}
goto done;
case COMPST_EXIT:
if (qp->comp.timeout_retry && wqe) {
state = COMPST_ERROR_RETRY;
break;
}
/* re reset the timeout counter if
* (1) QP is type RC
* (2) the QP is alive
* (3) there is a packet sent by the requester that
* might be acked (we still might get spurious
* timeouts but try to keep them as few as possible)
* (4) the timeout parameter is set
*/
if ((qp_type(qp) == IB_QPT_RC) &&
(qp->req.state == QP_STATE_READY) &&
(psn_compare(qp->req.psn, qp->comp.psn) > 0) &&
qp->qp_timeout_jiffies)
mod_timer(&qp->retrans_timer,
jiffies + qp->qp_timeout_jiffies);
WARN_ON_ONCE(skb);
goto exit;
case COMPST_ERROR_RETRY:
/* we come here if the retry timer fired and we did
* not receive a response packet. try to retry the send
* queue if that makes sense and the limits have not
* been exceeded. remember that some timeouts are
* spurious since we do not reset the timer but kick
* it down the road or let it expire
*/
/* there is nothing to retry in this case */
if (!wqe || (wqe->state == wqe_state_posted)) {
WARN_ON_ONCE(skb);
goto exit;
}
if (qp->comp.retry_cnt > 0) {
if (qp->comp.retry_cnt != 7)
qp->comp.retry_cnt--;
/* no point in retrying if we have already
* seen the last ack that the requester could
* have caused
*/
if (psn_compare(qp->req.psn,
qp->comp.psn) > 0) {
/* tell the requester to retry the
* send send queue next time around
*/
qp->req.need_retry = 1;
rxe_run_task(&qp->req.task, 1);
}
if (pkt) {
rxe_drop_ref(pkt->qp);
kfree_skb(skb);
skb = NULL;
}
WARN_ON_ONCE(skb);
goto exit;
} else {
wqe->status = IB_WC_RETRY_EXC_ERR;
state = COMPST_ERROR;
}
break;
case COMPST_RNR_RETRY:
if (qp->comp.rnr_retry > 0) {
if (qp->comp.rnr_retry != 7)
qp->comp.rnr_retry--;
qp->req.need_retry = 1;
pr_debug("qp#%d set rnr nak timer\n",
qp_num(qp));
mod_timer(&qp->rnr_nak_timer,
jiffies + rnrnak_jiffies(aeth_syn(pkt)
& ~AETH_TYPE_MASK));
rxe_drop_ref(pkt->qp);
kfree_skb(skb);
skb = NULL;
goto exit;
} else {
wqe->status = IB_WC_RNR_RETRY_EXC_ERR;
state = COMPST_ERROR;
}
break;
case COMPST_ERROR:
WARN_ON_ONCE(wqe->status == IB_WC_SUCCESS);
do_complete(qp, wqe);
rxe_qp_error(qp);
if (pkt) {
rxe_drop_ref(pkt->qp);
kfree_skb(skb);
skb = NULL;
}
WARN_ON_ONCE(skb);
goto exit;
}
}
exit:
/* we come here if we are done with processing and want the task to
* exit from the loop calling us
*/
WARN_ON_ONCE(skb);
rxe_drop_ref(qp);
return -EAGAIN;
done:
/* we come here if we have processed a packet we want the task to call
* us again to see if there is anything else to do
*/
WARN_ON_ONCE(skb);
rxe_drop_ref(qp);
return 0;
}
