IPoIB: Fix AH leak at interface down

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / infiniband / ulp / ipoib / ipoib_ib.c

/*
 * Copyright (c) 2004, 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
 * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
 * Copyright (c) 2004, 2005 Voltaire, 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.
 *
 * $Id: ipoib_ib.c 1386 2004-12-27 16:23:17Z roland $
 */

#include <linux/delay.h>
#include <linux/dma-mapping.h>

#include <rdma/ib_cache.h>

#include "ipoib.h"

#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG_DATA
static int data_debug_level;

module_param(data_debug_level, int, 0644);
MODULE_PARM_DESC(data_debug_level,
                 "Enable data path debug tracing if > 0");
#endif

#define IPOIB_OP_RECV   (1ul << 31)

static DEFINE_MUTEX(pkey_mutex);

struct ipoib_ah *ipoib_create_ah(struct net_device *dev,
                                 struct ib_pd *pd, struct ib_ah_attr *attr)
{
        struct ipoib_ah *ah;

        ah = kmalloc(sizeof *ah, GFP_KERNEL);
        if (!ah)
                return NULL;

        ah->dev       = dev;
        ah->last_send = 0;
        kref_init(&ah->ref);

        ah->ah = ib_create_ah(pd, attr);
        if (IS_ERR(ah->ah)) {
                kfree(ah);
                ah = NULL;
        } else
                ipoib_dbg(netdev_priv(dev), "Created ah %p\n", ah->ah);

        return ah;
}

void ipoib_free_ah(struct kref *kref)
{
        struct ipoib_ah *ah = container_of(kref, struct ipoib_ah, ref);
        struct ipoib_dev_priv *priv = netdev_priv(ah->dev);

        unsigned long flags;

        if ((int) priv->tx_tail - (int) ah->last_send >= 0) {
                ipoib_dbg(priv, "Freeing ah %p\n", ah->ah);
                ib_destroy_ah(ah->ah);
                kfree(ah);
        } else {
                spin_lock_irqsave(&priv->lock, flags);
                list_add_tail(&ah->list, &priv->dead_ahs);
                spin_unlock_irqrestore(&priv->lock, flags);
        }
}

static int ipoib_ib_post_receive(struct net_device *dev, int id)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        struct ib_sge list;
        struct ib_recv_wr param;
        struct ib_recv_wr *bad_wr;
        int ret;

        list.addr     = priv->rx_ring[id].mapping;
        list.length   = IPOIB_BUF_SIZE;
        list.lkey     = priv->mr->lkey;

        param.next    = NULL;
        param.wr_id   = id | IPOIB_OP_RECV;
        param.sg_list = &list;
        param.num_sge = 1;

        ret = ib_post_recv(priv->qp, &param, &bad_wr);
        if (unlikely(ret)) {
                ipoib_warn(priv, "receive failed for buf %d (%d)\n", id, ret);
                dma_unmap_single(priv->ca->dma_device,
                                 priv->rx_ring[id].mapping,
                                 IPOIB_BUF_SIZE, DMA_FROM_DEVICE);
                dev_kfree_skb_any(priv->rx_ring[id].skb);
                priv->rx_ring[id].skb = NULL;
        }

        return ret;
}

static int ipoib_alloc_rx_skb(struct net_device *dev, int id)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        struct sk_buff *skb;
        dma_addr_t addr;

        skb = dev_alloc_skb(IPOIB_BUF_SIZE + 4);
        if (!skb)
                return -ENOMEM;

        /*
         * IB will leave a 40 byte gap for a GRH and IPoIB adds a 4 byte
         * header.  So we need 4 more bytes to get to 48 and align the
         * IP header to a multiple of 16.
         */
        skb_reserve(skb, 4);

        addr = dma_map_single(priv->ca->dma_device,
                              skb->data, IPOIB_BUF_SIZE,
                              DMA_FROM_DEVICE);
        if (unlikely(dma_mapping_error(addr))) {
                dev_kfree_skb_any(skb);
                return -EIO;
        }

        priv->rx_ring[id].skb     = skb;
        priv->rx_ring[id].mapping = addr;

        return 0;
}

static int ipoib_ib_post_receives(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        int i;

        for (i = 0; i < ipoib_recvq_size; ++i) {
                if (ipoib_alloc_rx_skb(dev, i)) {
                        ipoib_warn(priv, "failed to allocate receive buffer %d\n", i);
                        return -ENOMEM;
                }
                if (ipoib_ib_post_receive(dev, i)) {
                        ipoib_warn(priv, "ipoib_ib_post_receive failed for buf %d\n", i);
                        return -EIO;
                }
        }

        return 0;
}

static void ipoib_ib_handle_wc(struct net_device *dev,
                               struct ib_wc *wc)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        unsigned int wr_id = wc->wr_id;

        ipoib_dbg_data(priv, "called: id %d, op %d, status: %d\n",
                       wr_id, wc->opcode, wc->status);

        if (wr_id & IPOIB_OP_RECV) {
                wr_id &= ~IPOIB_OP_RECV;

                if (wr_id < ipoib_recvq_size) {
                        struct sk_buff *skb  = priv->rx_ring[wr_id].skb;
                        dma_addr_t      addr = priv->rx_ring[wr_id].mapping;

                        if (unlikely(wc->status != IB_WC_SUCCESS)) {
                                if (wc->status != IB_WC_WR_FLUSH_ERR)
                                        ipoib_warn(priv, "failed recv event "
                                                   "(status=%d, wrid=%d vend_err %x)\n",
                                                   wc->status, wr_id, wc->vendor_err);
                                dma_unmap_single(priv->ca->dma_device, addr,
                                                 IPOIB_BUF_SIZE, DMA_FROM_DEVICE);
                                dev_kfree_skb_any(skb);
                                priv->rx_ring[wr_id].skb = NULL;
                                return;
                        }

                        /*
                         * If we can't allocate a new RX buffer, dump
                         * this packet and reuse the old buffer.
                         */
                        if (unlikely(ipoib_alloc_rx_skb(dev, wr_id))) {
                                ++priv->stats.rx_dropped;
                                goto repost;
                        }

                        ipoib_dbg_data(priv, "received %d bytes, SLID 0x%04x\n",
                                       wc->byte_len, wc->slid);

                        dma_unmap_single(priv->ca->dma_device, addr,
                                         IPOIB_BUF_SIZE, DMA_FROM_DEVICE);

                        skb_put(skb, wc->byte_len);
                        skb_pull(skb, IB_GRH_BYTES);

                        if (wc->slid != priv->local_lid ||
                            wc->src_qp != priv->qp->qp_num) {
                                skb->protocol = ((struct ipoib_header *) skb->data)->proto;
                                skb->mac.raw = skb->data;
                                skb_pull(skb, IPOIB_ENCAP_LEN);

                                dev->last_rx = jiffies;
                                ++priv->stats.rx_packets;
                                priv->stats.rx_bytes += skb->len;

                                skb->dev = dev;
                                /* XXX get correct PACKET_ type here */
                                skb->pkt_type = PACKET_HOST;
                                netif_rx_ni(skb);
                        } else {
                                ipoib_dbg_data(priv, "dropping loopback packet\n");
                                dev_kfree_skb_any(skb);
                        }

                repost:
                        if (unlikely(ipoib_ib_post_receive(dev, wr_id)))
                                ipoib_warn(priv, "ipoib_ib_post_receive failed "
                                           "for buf %d\n", wr_id);
                } else
                        ipoib_warn(priv, "completion event with wrid %d\n",
                                   wr_id);

        } else {
                struct ipoib_tx_buf *tx_req;
                unsigned long flags;

                if (wr_id >= ipoib_sendq_size) {
                        ipoib_warn(priv, "completion event with wrid %d (> %d)\n",
                                   wr_id, ipoib_sendq_size);
                        return;
                }

                ipoib_dbg_data(priv, "send complete, wrid %d\n", wr_id);

                tx_req = &priv->tx_ring[wr_id];

                dma_unmap_single(priv->ca->dma_device,
                                 pci_unmap_addr(tx_req, mapping),
                                 tx_req->skb->len,
                                 DMA_TO_DEVICE);

                ++priv->stats.tx_packets;
                priv->stats.tx_bytes += tx_req->skb->len;

                dev_kfree_skb_any(tx_req->skb);

                spin_lock_irqsave(&priv->tx_lock, flags);
                ++priv->tx_tail;
                if (netif_queue_stopped(dev) &&
                    test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags) &&
                    priv->tx_head - priv->tx_tail <= ipoib_sendq_size >> 1)
                        netif_wake_queue(dev);
                spin_unlock_irqrestore(&priv->tx_lock, flags);

                if (wc->status != IB_WC_SUCCESS &&
                    wc->status != IB_WC_WR_FLUSH_ERR)
                        ipoib_warn(priv, "failed send event "
                                   "(status=%d, wrid=%d vend_err %x)\n",
                                   wc->status, wr_id, wc->vendor_err);
        }
}

void ipoib_ib_completion(struct ib_cq *cq, void *dev_ptr)
{
        struct net_device *dev = (struct net_device *) dev_ptr;
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        int n, i;

        ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
        do {
                n = ib_poll_cq(cq, IPOIB_NUM_WC, priv->ibwc);
                for (i = 0; i < n; ++i)
                        ipoib_ib_handle_wc(dev, priv->ibwc + i);
        } while (n == IPOIB_NUM_WC);
}

static inline int post_send(struct ipoib_dev_priv *priv,
                            unsigned int wr_id,
                            struct ib_ah *address, u32 qpn,
                            dma_addr_t addr, int len)
{
        struct ib_send_wr *bad_wr;

        priv->tx_sge.addr             = addr;
        priv->tx_sge.length           = len;

        priv->tx_wr.wr_id             = wr_id;
        priv->tx_wr.wr.ud.remote_qpn  = qpn;
        priv->tx_wr.wr.ud.ah          = address;

        return ib_post_send(priv->qp, &priv->tx_wr, &bad_wr);
}

void ipoib_send(struct net_device *dev, struct sk_buff *skb,
                struct ipoib_ah *address, u32 qpn)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        struct ipoib_tx_buf *tx_req;
        dma_addr_t addr;

        if (skb->len > dev->mtu + INFINIBAND_ALEN) {
                ipoib_warn(priv, "packet len %d (> %d) too long to send, dropping\n",
                           skb->len, dev->mtu + INFINIBAND_ALEN);
                ++priv->stats.tx_dropped;
                ++priv->stats.tx_errors;
                dev_kfree_skb_any(skb);
                return;
        }

        ipoib_dbg_data(priv, "sending packet, length=%d address=%p qpn=0x%06x\n",
                       skb->len, address, qpn);

        /*
         * We put the skb into the tx_ring _before_ we call post_send()
         * because it's entirely possible that the completion handler will
         * run before we execute anything after the post_send().  That
         * means we have to make sure everything is properly recorded and
         * our state is consistent before we call post_send().
         */
        tx_req = &priv->tx_ring[priv->tx_head & (ipoib_sendq_size - 1)];
        tx_req->skb = skb;
        addr = dma_map_single(priv->ca->dma_device, skb->data, skb->len,
                              DMA_TO_DEVICE);
        pci_unmap_addr_set(tx_req, mapping, addr);

        if (unlikely(post_send(priv, priv->tx_head & (ipoib_sendq_size - 1),
                               address->ah, qpn, addr, skb->len))) {
                ipoib_warn(priv, "post_send failed\n");
                ++priv->stats.tx_errors;
                dma_unmap_single(priv->ca->dma_device, addr, skb->len,
                                 DMA_TO_DEVICE);
                dev_kfree_skb_any(skb);
        } else {
                dev->trans_start = jiffies;

                address->last_send = priv->tx_head;
                ++priv->tx_head;

                if (priv->tx_head - priv->tx_tail == ipoib_sendq_size) {
                        ipoib_dbg(priv, "TX ring full, stopping kernel net queue\n");
                        netif_stop_queue(dev);
                }
        }
}

static void __ipoib_reap_ah(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        struct ipoib_ah *ah, *tah;
        LIST_HEAD(remove_list);

        spin_lock_irq(&priv->lock);
        list_for_each_entry_safe(ah, tah, &priv->dead_ahs, list)
                if ((int) priv->tx_tail - (int) ah->last_send >= 0) {
                        list_del(&ah->list);
                        list_add_tail(&ah->list, &remove_list);
                }
        spin_unlock_irq(&priv->lock);

        list_for_each_entry_safe(ah, tah, &remove_list, list) {
                ipoib_dbg(priv, "Reaping ah %p\n", ah->ah);
                ib_destroy_ah(ah->ah);
                kfree(ah);
        }
}

void ipoib_reap_ah(void *dev_ptr)
{
        struct net_device *dev = dev_ptr;
        struct ipoib_dev_priv *priv = netdev_priv(dev);

        __ipoib_reap_ah(dev);

        if (!test_bit(IPOIB_STOP_REAPER, &priv->flags))
                queue_delayed_work(ipoib_workqueue, &priv->ah_reap_task, HZ);
}

int ipoib_ib_dev_open(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        int ret;

        ret = ipoib_init_qp(dev);
        if (ret) {
                ipoib_warn(priv, "ipoib_init_qp returned %d\n", ret);
                return -1;
        }

        ret = ipoib_ib_post_receives(dev);
        if (ret) {
                ipoib_warn(priv, "ipoib_ib_post_receives returned %d\n", ret);
                ipoib_ib_dev_stop(dev);
                return -1;
        }

        clear_bit(IPOIB_STOP_REAPER, &priv->flags);
        queue_delayed_work(ipoib_workqueue, &priv->ah_reap_task, HZ);

        set_bit(IPOIB_FLAG_INITIALIZED, &priv->flags);

        return 0;
}

static void ipoib_pkey_dev_check_presence(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        u16 pkey_index = 0;

        if (ib_find_cached_pkey(priv->ca, priv->port, priv->pkey, &pkey_index))
                clear_bit(IPOIB_PKEY_ASSIGNED, &priv->flags);
        else
                set_bit(IPOIB_PKEY_ASSIGNED, &priv->flags);
}

int ipoib_ib_dev_up(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);

        ipoib_pkey_dev_check_presence(dev);

        if (!test_bit(IPOIB_PKEY_ASSIGNED, &priv->flags)) {
                ipoib_dbg(priv, "PKEY is not assigned.\n");
                return 0;
        }

        set_bit(IPOIB_FLAG_OPER_UP, &priv->flags);

        return ipoib_mcast_start_thread(dev);
}

int ipoib_ib_dev_down(struct net_device *dev, int flush)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);

        ipoib_dbg(priv, "downing ib_dev\n");

        clear_bit(IPOIB_FLAG_OPER_UP, &priv->flags);
        netif_carrier_off(dev);

        /* Shutdown the P_Key thread if still active */
        if (!test_bit(IPOIB_PKEY_ASSIGNED, &priv->flags)) {
                mutex_lock(&pkey_mutex);
                set_bit(IPOIB_PKEY_STOP, &priv->flags);
                cancel_delayed_work(&priv->pkey_task);
                mutex_unlock(&pkey_mutex);
                if (flush)
                        flush_workqueue(ipoib_workqueue);
        }

        ipoib_mcast_stop_thread(dev, flush);
        ipoib_mcast_dev_flush(dev);

        ipoib_flush_paths(dev);

        return 0;
}

static int recvs_pending(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        int pending = 0;
        int i;

        for (i = 0; i < ipoib_recvq_size; ++i)
                if (priv->rx_ring[i].skb)
                        ++pending;

        return pending;
}

int ipoib_ib_dev_stop(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);
        struct ib_qp_attr qp_attr;
        unsigned long begin;
        struct ipoib_tx_buf *tx_req;
        int i;

        clear_bit(IPOIB_FLAG_INITIALIZED, &priv->flags);

        /*
         * Move our QP to the error state and then reinitialize in
         * when all work requests have completed or have been flushed.
         */
        qp_attr.qp_state = IB_QPS_ERR;
        if (ib_modify_qp(priv->qp, &qp_attr, IB_QP_STATE))
                ipoib_warn(priv, "Failed to modify QP to ERROR state\n");

        /* Wait for all sends and receives to complete */
        begin = jiffies;

        while (priv->tx_head != priv->tx_tail || recvs_pending(dev)) {
                if (time_after(jiffies, begin + 5 * HZ)) {
                        ipoib_warn(priv, "timing out; %d sends %d receives not completed\n",
                                   priv->tx_head - priv->tx_tail, recvs_pending(dev));

                        /*
                         * assume the HW is wedged and just free up
                         * all our pending work requests.
                         */
                        while ((int) priv->tx_tail - (int) priv->tx_head < 0) {
                                tx_req = &priv->tx_ring[priv->tx_tail &
                                                        (ipoib_sendq_size - 1)];
                                dma_unmap_single(priv->ca->dma_device,
                                                 pci_unmap_addr(tx_req, mapping),
                                                 tx_req->skb->len,
                                                 DMA_TO_DEVICE);
                                dev_kfree_skb_any(tx_req->skb);
                                ++priv->tx_tail;
                        }

                        for (i = 0; i < ipoib_recvq_size; ++i)
                                if (priv->rx_ring[i].skb) {
                                        dma_unmap_single(priv->ca->dma_device,
                                                         pci_unmap_addr(&priv->rx_ring[i],
                                                                        mapping),
                                                         IPOIB_BUF_SIZE,
                                                         DMA_FROM_DEVICE);
                                        dev_kfree_skb_any(priv->rx_ring[i].skb);
                                        priv->rx_ring[i].skb = NULL;
                                }

                        goto timeout;
                }

                msleep(1);
        }

        ipoib_dbg(priv, "All sends and receives done.\n");

timeout:
        qp_attr.qp_state = IB_QPS_RESET;
        if (ib_modify_qp(priv->qp, &qp_attr, IB_QP_STATE))
                ipoib_warn(priv, "Failed to modify QP to RESET state\n");

        /* Wait for all AHs to be reaped */
        set_bit(IPOIB_STOP_REAPER, &priv->flags);
        cancel_delayed_work(&priv->ah_reap_task);
        flush_workqueue(ipoib_workqueue);

        begin = jiffies;

        while (!list_empty(&priv->dead_ahs)) {
                __ipoib_reap_ah(dev);

                if (time_after(jiffies, begin + HZ)) {
                        ipoib_warn(priv, "timing out; will leak address handles\n");
                        break;
                }

                msleep(1);
        }

        return 0;
}

int ipoib_ib_dev_init(struct net_device *dev, struct ib_device *ca, int port)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);

        priv->ca = ca;
        priv->port = port;
        priv->qp = NULL;

        if (ipoib_transport_dev_init(dev, ca)) {
                printk(KERN_WARNING "%s: ipoib_transport_dev_init failed\n", ca->name);
                return -ENODEV;
        }

        if (dev->flags & IFF_UP) {
                if (ipoib_ib_dev_open(dev)) {
                        ipoib_transport_dev_cleanup(dev);
                        return -ENODEV;
                }
        }

        return 0;
}

void ipoib_ib_dev_flush(void *_dev)
{
        struct net_device *dev = (struct net_device *)_dev;
        struct ipoib_dev_priv *priv = netdev_priv(dev), *cpriv;

        if (!test_bit(IPOIB_FLAG_INITIALIZED, &priv->flags) ) {
                ipoib_dbg(priv, "Not flushing - IPOIB_FLAG_INITIALIZED not set.\n");
                return;
        }

        if (!test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags)) {
                ipoib_dbg(priv, "Not flushing - IPOIB_FLAG_ADMIN_UP not set.\n");
                return;
        }

        ipoib_dbg(priv, "flushing\n");

        ipoib_ib_dev_down(dev, 0);

        /*
         * The device could have been brought down between the start and when
         * we get here, don't bring it back up if it's not configured up
         */
        if (test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
                ipoib_ib_dev_up(dev);

        mutex_lock(&priv->vlan_mutex);

        /* Flush any child interfaces too */
        list_for_each_entry(cpriv, &priv->child_intfs, list)
                ipoib_ib_dev_flush(cpriv->dev);

        mutex_unlock(&priv->vlan_mutex);
}

void ipoib_ib_dev_cleanup(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);

        ipoib_dbg(priv, "cleaning up ib_dev\n");

        ipoib_mcast_stop_thread(dev, 1);
        ipoib_mcast_dev_flush(dev);

        ipoib_transport_dev_cleanup(dev);
}

/*
 * Delayed P_Key Assigment Interim Support
 *
 * The following is initial implementation of delayed P_Key assigment
 * mechanism. It is using the same approach implemented for the multicast
 * group join. The single goal of this implementation is to quickly address
 * Bug #2507. This implementation will probably be removed when the P_Key
 * change async notification is available.
 */

void ipoib_pkey_poll(void *dev_ptr)
{
        struct net_device *dev = dev_ptr;
        struct ipoib_dev_priv *priv = netdev_priv(dev);

        ipoib_pkey_dev_check_presence(dev);

        if (test_bit(IPOIB_PKEY_ASSIGNED, &priv->flags))
                ipoib_open(dev);
        else {
                mutex_lock(&pkey_mutex);
                if (!test_bit(IPOIB_PKEY_STOP, &priv->flags))
                        queue_delayed_work(ipoib_workqueue,
                                           &priv->pkey_task,
                                           HZ);
                mutex_unlock(&pkey_mutex);
        }
}

int ipoib_pkey_dev_delay_open(struct net_device *dev)
{
        struct ipoib_dev_priv *priv = netdev_priv(dev);

        /* Look for the interface pkey value in the IB Port P_Key table and */
        /* set the interface pkey assigment flag                            */
        ipoib_pkey_dev_check_presence(dev);

        /* P_Key value not assigned yet - start polling */
        if (!test_bit(IPOIB_PKEY_ASSIGNED, &priv->flags)) {
                mutex_lock(&pkey_mutex);
                clear_bit(IPOIB_PKEY_STOP, &priv->flags);
                queue_delayed_work(ipoib_workqueue,
                                   &priv->pkey_task,
                                   HZ);
                mutex_unlock(&pkey_mutex);
                return 1;
        }

        return 0;
}