ath9k: Fix bug in handling rx frames with invalid descriptor content

[deliverable/linux.git] / drivers / net / wireless / ath / ath9k / recv.c

/*
 * Copyright (c) 2008-2009 Atheros Communications Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "ath9k.h"
#include "ar9003_mac.h"

#define SKB_CB_ATHBUF(__skb)    (*((struct ath_buf **)__skb->cb))

static struct ieee80211_hw * ath_get_virt_hw(struct ath_softc *sc,
                                             struct ieee80211_hdr *hdr)
{
        struct ieee80211_hw *hw = sc->pri_wiphy->hw;
        int i;

        spin_lock_bh(&sc->wiphy_lock);
        for (i = 0; i < sc->num_sec_wiphy; i++) {
                struct ath_wiphy *aphy = sc->sec_wiphy[i];
                if (aphy == NULL)
                        continue;
                if (compare_ether_addr(hdr->addr1, aphy->hw->wiphy->perm_addr)
                    == 0) {
                        hw = aphy->hw;
                        break;
                }
        }
        spin_unlock_bh(&sc->wiphy_lock);
        return hw;
}

/*
 * Setup and link descriptors.
 *
 * 11N: we can no longer afford to self link the last descriptor.
 * MAC acknowledges BA status as long as it copies frames to host
 * buffer (or rx fifo). This can incorrectly acknowledge packets
 * to a sender if last desc is self-linked.
 */
static void ath_rx_buf_link(struct ath_softc *sc, struct ath_buf *bf)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_desc *ds;
        struct sk_buff *skb;

        ATH_RXBUF_RESET(bf);

        ds = bf->bf_desc;
        ds->ds_link = 0; /* link to null */
        ds->ds_data = bf->bf_buf_addr;

        /* virtual addr of the beginning of the buffer. */
        skb = bf->bf_mpdu;
        BUG_ON(skb == NULL);
        ds->ds_vdata = skb->data;

        /*
         * setup rx descriptors. The rx_bufsize here tells the hardware
         * how much data it can DMA to us and that we are prepared
         * to process
         */
        ath9k_hw_setuprxdesc(ah, ds,
                             common->rx_bufsize,
                             0);

        if (sc->rx.rxlink == NULL)
                ath9k_hw_putrxbuf(ah, bf->bf_daddr);
        else
                *sc->rx.rxlink = bf->bf_daddr;

        sc->rx.rxlink = &ds->ds_link;
        ath9k_hw_rxena(ah);
}

static void ath_setdefantenna(struct ath_softc *sc, u32 antenna)
{
        /* XXX block beacon interrupts */
        ath9k_hw_setantenna(sc->sc_ah, antenna);
        sc->rx.defant = antenna;
        sc->rx.rxotherant = 0;
}

static void ath_opmode_init(struct ath_softc *sc)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);

        u32 rfilt, mfilt[2];

        /* configure rx filter */
        rfilt = ath_calcrxfilter(sc);
        ath9k_hw_setrxfilter(ah, rfilt);

        /* configure bssid mask */
        if (ah->caps.hw_caps & ATH9K_HW_CAP_BSSIDMASK)
                ath_hw_setbssidmask(common);

        /* configure operational mode */
        ath9k_hw_setopmode(ah);

        /* Handle any link-level address change. */
        ath9k_hw_setmac(ah, common->macaddr);

        /* calculate and install multicast filter */
        mfilt[0] = mfilt[1] = ~0;
        ath9k_hw_setmcastfilter(ah, mfilt[0], mfilt[1]);
}

static bool ath_rx_edma_buf_link(struct ath_softc *sc,
                                 enum ath9k_rx_qtype qtype)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_rx_edma *rx_edma;
        struct sk_buff *skb;
        struct ath_buf *bf;

        rx_edma = &sc->rx.rx_edma[qtype];
        if (skb_queue_len(&rx_edma->rx_fifo) >= rx_edma->rx_fifo_hwsize)
                return false;

        bf = list_first_entry(&sc->rx.rxbuf, struct ath_buf, list);
        list_del_init(&bf->list);

        skb = bf->bf_mpdu;

        ATH_RXBUF_RESET(bf);
        memset(skb->data, 0, ah->caps.rx_status_len);
        dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
                                ah->caps.rx_status_len, DMA_TO_DEVICE);

        SKB_CB_ATHBUF(skb) = bf;
        ath9k_hw_addrxbuf_edma(ah, bf->bf_buf_addr, qtype);
        skb_queue_tail(&rx_edma->rx_fifo, skb);

        return true;
}

static void ath_rx_addbuffer_edma(struct ath_softc *sc,
                                  enum ath9k_rx_qtype qtype, int size)
{
        struct ath_rx_edma *rx_edma;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        u32 nbuf = 0;

        rx_edma = &sc->rx.rx_edma[qtype];
        if (list_empty(&sc->rx.rxbuf)) {
                ath_print(common, ATH_DBG_QUEUE, "No free rx buf available\n");
                return;
        }

        while (!list_empty(&sc->rx.rxbuf)) {
                nbuf++;

                if (!ath_rx_edma_buf_link(sc, qtype))
                        break;

                if (nbuf >= size)
                        break;
        }
}

static void ath_rx_remove_buffer(struct ath_softc *sc,
                                 enum ath9k_rx_qtype qtype)
{
        struct ath_buf *bf;
        struct ath_rx_edma *rx_edma;
        struct sk_buff *skb;

        rx_edma = &sc->rx.rx_edma[qtype];

        while ((skb = skb_dequeue(&rx_edma->rx_fifo)) != NULL) {
                bf = SKB_CB_ATHBUF(skb);
                BUG_ON(!bf);
                list_add_tail(&bf->list, &sc->rx.rxbuf);
        }
}

static void ath_rx_edma_cleanup(struct ath_softc *sc)
{
        struct ath_buf *bf;

        ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_LP);
        ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_HP);

        list_for_each_entry(bf, &sc->rx.rxbuf, list) {
                if (bf->bf_mpdu)
                        dev_kfree_skb_any(bf->bf_mpdu);
        }

        INIT_LIST_HEAD(&sc->rx.rxbuf);

        kfree(sc->rx.rx_bufptr);
        sc->rx.rx_bufptr = NULL;
}

static void ath_rx_edma_init_queue(struct ath_rx_edma *rx_edma, int size)
{
        skb_queue_head_init(&rx_edma->rx_fifo);
        skb_queue_head_init(&rx_edma->rx_buffers);
        rx_edma->rx_fifo_hwsize = size;
}

static int ath_rx_edma_init(struct ath_softc *sc, int nbufs)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct ath_hw *ah = sc->sc_ah;
        struct sk_buff *skb;
        struct ath_buf *bf;
        int error = 0, i;
        u32 size;


        common->rx_bufsize = roundup(IEEE80211_MAX_MPDU_LEN +
                                     ah->caps.rx_status_len,
                                     min(common->cachelsz, (u16)64));

        ath9k_hw_set_rx_bufsize(ah, common->rx_bufsize -
                                    ah->caps.rx_status_len);

        ath_rx_edma_init_queue(&sc->rx.rx_edma[ATH9K_RX_QUEUE_LP],
                               ah->caps.rx_lp_qdepth);
        ath_rx_edma_init_queue(&sc->rx.rx_edma[ATH9K_RX_QUEUE_HP],
                               ah->caps.rx_hp_qdepth);

        size = sizeof(struct ath_buf) * nbufs;
        bf = kzalloc(size, GFP_KERNEL);
        if (!bf)
                return -ENOMEM;

        INIT_LIST_HEAD(&sc->rx.rxbuf);
        sc->rx.rx_bufptr = bf;

        for (i = 0; i < nbufs; i++, bf++) {
                skb = ath_rxbuf_alloc(common, common->rx_bufsize, GFP_KERNEL);
                if (!skb) {
                        error = -ENOMEM;
                        goto rx_init_fail;
                }

                memset(skb->data, 0, common->rx_bufsize);
                bf->bf_mpdu = skb;

                bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
                                                 common->rx_bufsize,
                                                 DMA_BIDIRECTIONAL);
                if (unlikely(dma_mapping_error(sc->dev,
                                                bf->bf_buf_addr))) {
                                dev_kfree_skb_any(skb);
                                bf->bf_mpdu = NULL;
                                ath_print(common, ATH_DBG_FATAL,
                                        "dma_mapping_error() on RX init\n");
                                error = -ENOMEM;
                                goto rx_init_fail;
                }

                list_add_tail(&bf->list, &sc->rx.rxbuf);
        }

        return 0;

rx_init_fail:
        ath_rx_edma_cleanup(sc);
        return error;
}

static void ath_edma_start_recv(struct ath_softc *sc)
{
        spin_lock_bh(&sc->rx.rxbuflock);

        ath9k_hw_rxena(sc->sc_ah);

        ath_rx_addbuffer_edma(sc, ATH9K_RX_QUEUE_HP,
                              sc->rx.rx_edma[ATH9K_RX_QUEUE_HP].rx_fifo_hwsize);

        ath_rx_addbuffer_edma(sc, ATH9K_RX_QUEUE_LP,
                              sc->rx.rx_edma[ATH9K_RX_QUEUE_LP].rx_fifo_hwsize);

        spin_unlock_bh(&sc->rx.rxbuflock);

        ath_opmode_init(sc);

        ath9k_hw_startpcureceive(sc->sc_ah);
}

static void ath_edma_stop_recv(struct ath_softc *sc)
{
        spin_lock_bh(&sc->rx.rxbuflock);
        ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_HP);
        ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_LP);
        spin_unlock_bh(&sc->rx.rxbuflock);
}

int ath_rx_init(struct ath_softc *sc, int nbufs)
{
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);
        struct sk_buff *skb;
        struct ath_buf *bf;
        int error = 0;

        spin_lock_init(&sc->rx.rxflushlock);
        sc->sc_flags &= ~SC_OP_RXFLUSH;
        spin_lock_init(&sc->rx.rxbuflock);

        if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
                return ath_rx_edma_init(sc, nbufs);
        } else {
                common->rx_bufsize = roundup(IEEE80211_MAX_MPDU_LEN,
                                min(common->cachelsz, (u16)64));

                ath_print(common, ATH_DBG_CONFIG, "cachelsz %u rxbufsize %u\n",
                                common->cachelsz, common->rx_bufsize);

                /* Initialize rx descriptors */

                error = ath_descdma_setup(sc, &sc->rx.rxdma, &sc->rx.rxbuf,
                                "rx", nbufs, 1, 0);
                if (error != 0) {
                        ath_print(common, ATH_DBG_FATAL,
                                  "failed to allocate rx descriptors: %d\n",
                                  error);
                        goto err;
                }

                list_for_each_entry(bf, &sc->rx.rxbuf, list) {
                        skb = ath_rxbuf_alloc(common, common->rx_bufsize,
                                              GFP_KERNEL);
                        if (skb == NULL) {
                                error = -ENOMEM;
                                goto err;
                        }

                        bf->bf_mpdu = skb;
                        bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
                                        common->rx_bufsize,
                                        DMA_FROM_DEVICE);
                        if (unlikely(dma_mapping_error(sc->dev,
                                                        bf->bf_buf_addr))) {
                                dev_kfree_skb_any(skb);
                                bf->bf_mpdu = NULL;
                                ath_print(common, ATH_DBG_FATAL,
                                          "dma_mapping_error() on RX init\n");
                                error = -ENOMEM;
                                goto err;
                        }
                        bf->bf_dmacontext = bf->bf_buf_addr;
                }
                sc->rx.rxlink = NULL;
        }

err:
        if (error)
                ath_rx_cleanup(sc);

        return error;
}

void ath_rx_cleanup(struct ath_softc *sc)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct sk_buff *skb;
        struct ath_buf *bf;

        if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
                ath_rx_edma_cleanup(sc);
                return;
        } else {
                list_for_each_entry(bf, &sc->rx.rxbuf, list) {
                        skb = bf->bf_mpdu;
                        if (skb) {
                                dma_unmap_single(sc->dev, bf->bf_buf_addr,
                                                common->rx_bufsize,
                                                DMA_FROM_DEVICE);
                                dev_kfree_skb(skb);
                        }
                }

                if (sc->rx.rxdma.dd_desc_len != 0)
                        ath_descdma_cleanup(sc, &sc->rx.rxdma, &sc->rx.rxbuf);
        }
}

/*
 * Calculate the receive filter according to the
 * operating mode and state:
 *
 * o always accept unicast, broadcast, and multicast traffic
 * o maintain current state of phy error reception (the hal
 *   may enable phy error frames for noise immunity work)
 * o probe request frames are accepted only when operating in
 *   hostap, adhoc, or monitor modes
 * o enable promiscuous mode according to the interface state
 * o accept beacons:
 *   - when operating in adhoc mode so the 802.11 layer creates
 *     node table entries for peers,
 *   - when operating in station mode for collecting rssi data when
 *     the station is otherwise quiet, or
 *   - when operating as a repeater so we see repeater-sta beacons
 *   - when scanning
 */

u32 ath_calcrxfilter(struct ath_softc *sc)
{
#define RX_FILTER_PRESERVE (ATH9K_RX_FILTER_PHYERR | ATH9K_RX_FILTER_PHYRADAR)

        u32 rfilt;

        rfilt = (ath9k_hw_getrxfilter(sc->sc_ah) & RX_FILTER_PRESERVE)
                | ATH9K_RX_FILTER_UCAST | ATH9K_RX_FILTER_BCAST
                | ATH9K_RX_FILTER_MCAST;

        /* If not a STA, enable processing of Probe Requests */
        if (sc->sc_ah->opmode != NL80211_IFTYPE_STATION)
                rfilt |= ATH9K_RX_FILTER_PROBEREQ;

        /*
         * Set promiscuous mode when FIF_PROMISC_IN_BSS is enabled for station
         * mode interface or when in monitor mode. AP mode does not need this
         * since it receives all in-BSS frames anyway.
         */
        if (((sc->sc_ah->opmode != NL80211_IFTYPE_AP) &&
             (sc->rx.rxfilter & FIF_PROMISC_IN_BSS)) ||
            (sc->sc_ah->opmode == NL80211_IFTYPE_MONITOR))
                rfilt |= ATH9K_RX_FILTER_PROM;

        if (sc->rx.rxfilter & FIF_CONTROL)
                rfilt |= ATH9K_RX_FILTER_CONTROL;

        if ((sc->sc_ah->opmode == NL80211_IFTYPE_STATION) &&
            !(sc->rx.rxfilter & FIF_BCN_PRBRESP_PROMISC))
                rfilt |= ATH9K_RX_FILTER_MYBEACON;
        else
                rfilt |= ATH9K_RX_FILTER_BEACON;

        if ((AR_SREV_9280_10_OR_LATER(sc->sc_ah) ||
            AR_SREV_9285_10_OR_LATER(sc->sc_ah)) &&
            (sc->sc_ah->opmode == NL80211_IFTYPE_AP) &&
            (sc->rx.rxfilter & FIF_PSPOLL))
                rfilt |= ATH9K_RX_FILTER_PSPOLL;

        if (conf_is_ht(&sc->hw->conf))
                rfilt |= ATH9K_RX_FILTER_COMP_BAR;

        if (sc->sec_wiphy || (sc->rx.rxfilter & FIF_OTHER_BSS)) {
                /* TODO: only needed if more than one BSSID is in use in
                 * station/adhoc mode */
                /* The following may also be needed for other older chips */
                if (sc->sc_ah->hw_version.macVersion == AR_SREV_VERSION_9160)
                        rfilt |= ATH9K_RX_FILTER_PROM;
                rfilt |= ATH9K_RX_FILTER_MCAST_BCAST_ALL;
        }

        return rfilt;

#undef RX_FILTER_PRESERVE
}

int ath_startrecv(struct ath_softc *sc)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_buf *bf, *tbf;

        if (ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
                ath_edma_start_recv(sc);
                return 0;
        }

        spin_lock_bh(&sc->rx.rxbuflock);
        if (list_empty(&sc->rx.rxbuf))
                goto start_recv;

        sc->rx.rxlink = NULL;
        list_for_each_entry_safe(bf, tbf, &sc->rx.rxbuf, list) {
                ath_rx_buf_link(sc, bf);
        }

        /* We could have deleted elements so the list may be empty now */
        if (list_empty(&sc->rx.rxbuf))
                goto start_recv;

        bf = list_first_entry(&sc->rx.rxbuf, struct ath_buf, list);
        ath9k_hw_putrxbuf(ah, bf->bf_daddr);
        ath9k_hw_rxena(ah);

start_recv:
        spin_unlock_bh(&sc->rx.rxbuflock);
        ath_opmode_init(sc);
        ath9k_hw_startpcureceive(ah);

        return 0;
}

bool ath_stoprecv(struct ath_softc *sc)
{
        struct ath_hw *ah = sc->sc_ah;
        bool stopped;

        ath9k_hw_stoppcurecv(ah);
        ath9k_hw_setrxfilter(ah, 0);
        stopped = ath9k_hw_stopdmarecv(ah);

        if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
                ath_edma_stop_recv(sc);
        else
                sc->rx.rxlink = NULL;

        return stopped;
}

void ath_flushrecv(struct ath_softc *sc)
{
        spin_lock_bh(&sc->rx.rxflushlock);
        sc->sc_flags |= SC_OP_RXFLUSH;
        if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
                ath_rx_tasklet(sc, 1, true);
        ath_rx_tasklet(sc, 1, false);
        sc->sc_flags &= ~SC_OP_RXFLUSH;
        spin_unlock_bh(&sc->rx.rxflushlock);
}

static bool ath_beacon_dtim_pending_cab(struct sk_buff *skb)
{
        /* Check whether the Beacon frame has DTIM indicating buffered bc/mc */
        struct ieee80211_mgmt *mgmt;
        u8 *pos, *end, id, elen;
        struct ieee80211_tim_ie *tim;

        mgmt = (struct ieee80211_mgmt *)skb->data;
        pos = mgmt->u.beacon.variable;
        end = skb->data + skb->len;

        while (pos + 2 < end) {
                id = *pos++;
                elen = *pos++;
                if (pos + elen > end)
                        break;

                if (id == WLAN_EID_TIM) {
                        if (elen < sizeof(*tim))
                                break;
                        tim = (struct ieee80211_tim_ie *) pos;
                        if (tim->dtim_count != 0)
                                break;
                        return tim->bitmap_ctrl & 0x01;
                }

                pos += elen;
        }

        return false;
}

static void ath_rx_ps_beacon(struct ath_softc *sc, struct sk_buff *skb)
{
        struct ieee80211_mgmt *mgmt;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);

        if (skb->len < 24 + 8 + 2 + 2)
                return;

        mgmt = (struct ieee80211_mgmt *)skb->data;
        if (memcmp(common->curbssid, mgmt->bssid, ETH_ALEN) != 0)
                return; /* not from our current AP */

        sc->ps_flags &= ~PS_WAIT_FOR_BEACON;

        if (sc->ps_flags & PS_BEACON_SYNC) {
                sc->ps_flags &= ~PS_BEACON_SYNC;
                ath_print(common, ATH_DBG_PS,
                          "Reconfigure Beacon timers based on "
                          "timestamp from the AP\n");
                ath_beacon_config(sc, NULL);
        }

        if (ath_beacon_dtim_pending_cab(skb)) {
                /*
                 * Remain awake waiting for buffered broadcast/multicast
                 * frames. If the last broadcast/multicast frame is not
                 * received properly, the next beacon frame will work as
                 * a backup trigger for returning into NETWORK SLEEP state,
                 * so we are waiting for it as well.
                 */
                ath_print(common, ATH_DBG_PS, "Received DTIM beacon indicating "
                          "buffered broadcast/multicast frame(s)\n");
                sc->ps_flags |= PS_WAIT_FOR_CAB | PS_WAIT_FOR_BEACON;
                return;
        }

        if (sc->ps_flags & PS_WAIT_FOR_CAB) {
                /*
                 * This can happen if a broadcast frame is dropped or the AP
                 * fails to send a frame indicating that all CAB frames have
                 * been delivered.
                 */
                sc->ps_flags &= ~PS_WAIT_FOR_CAB;
                ath_print(common, ATH_DBG_PS,
                          "PS wait for CAB frames timed out\n");
        }
}

static void ath_rx_ps(struct ath_softc *sc, struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr;
        struct ath_common *common = ath9k_hw_common(sc->sc_ah);

        hdr = (struct ieee80211_hdr *)skb->data;

        /* Process Beacon and CAB receive in PS state */
        if ((sc->ps_flags & PS_WAIT_FOR_BEACON) &&
            ieee80211_is_beacon(hdr->frame_control))
                ath_rx_ps_beacon(sc, skb);
        else if ((sc->ps_flags & PS_WAIT_FOR_CAB) &&
                 (ieee80211_is_data(hdr->frame_control) ||
                  ieee80211_is_action(hdr->frame_control)) &&
                 is_multicast_ether_addr(hdr->addr1) &&
                 !ieee80211_has_moredata(hdr->frame_control)) {
                /*
                 * No more broadcast/multicast frames to be received at this
                 * point.
                 */
                sc->ps_flags &= ~PS_WAIT_FOR_CAB;
                ath_print(common, ATH_DBG_PS,
                          "All PS CAB frames received, back to sleep\n");
        } else if ((sc->ps_flags & PS_WAIT_FOR_PSPOLL_DATA) &&
                   !is_multicast_ether_addr(hdr->addr1) &&
                   !ieee80211_has_morefrags(hdr->frame_control)) {
                sc->ps_flags &= ~PS_WAIT_FOR_PSPOLL_DATA;
                ath_print(common, ATH_DBG_PS,
                          "Going back to sleep after having received "
                          "PS-Poll data (0x%lx)\n",
                        sc->ps_flags & (PS_WAIT_FOR_BEACON |
                                        PS_WAIT_FOR_CAB |
                                        PS_WAIT_FOR_PSPOLL_DATA |
                                        PS_WAIT_FOR_TX_ACK));
        }
}

static void ath_rx_send_to_mac80211(struct ieee80211_hw *hw,
                                    struct ath_softc *sc, struct sk_buff *skb,
                                    struct ieee80211_rx_status *rxs)
{
        struct ieee80211_hdr *hdr;

        hdr = (struct ieee80211_hdr *)skb->data;

        /* Send the frame to mac80211 */
        if (is_multicast_ether_addr(hdr->addr1)) {
                int i;
                /*
                 * Deliver broadcast/multicast frames to all suitable
                 * virtual wiphys.
                 */
                /* TODO: filter based on channel configuration */
                for (i = 0; i < sc->num_sec_wiphy; i++) {
                        struct ath_wiphy *aphy = sc->sec_wiphy[i];
                        struct sk_buff *nskb;
                        if (aphy == NULL)
                                continue;
                        nskb = skb_copy(skb, GFP_ATOMIC);
                        if (!nskb)
                                continue;
                        ieee80211_rx(aphy->hw, nskb);
                }
                ieee80211_rx(sc->hw, skb);
        } else
                /* Deliver unicast frames based on receiver address */
                ieee80211_rx(hw, skb);
}

static bool ath_edma_get_buffers(struct ath_softc *sc,
                                 enum ath9k_rx_qtype qtype)
{
        struct ath_rx_edma *rx_edma = &sc->rx.rx_edma[qtype];
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct sk_buff *skb;
        struct ath_buf *bf;
        int ret;

        skb = skb_peek(&rx_edma->rx_fifo);
        if (!skb)
                return false;

        bf = SKB_CB_ATHBUF(skb);
        BUG_ON(!bf);

        dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
                                common->rx_bufsize, DMA_FROM_DEVICE);

        ret = ath9k_hw_process_rxdesc_edma(ah, NULL, skb->data);
        if (ret == -EINPROGRESS)
                return false;

        __skb_unlink(skb, &rx_edma->rx_fifo);
        if (ret == -EINVAL) {
                /* corrupt descriptor, skip this one and the following one */
                list_add_tail(&bf->list, &sc->rx.rxbuf);
                ath_rx_edma_buf_link(sc, qtype);
                skb = skb_peek(&rx_edma->rx_fifo);
                if (!skb)
                        return true;

                bf = SKB_CB_ATHBUF(skb);
                BUG_ON(!bf);

                __skb_unlink(skb, &rx_edma->rx_fifo);
                list_add_tail(&bf->list, &sc->rx.rxbuf);
                ath_rx_edma_buf_link(sc, qtype);
                return true;
        }
        skb_queue_tail(&rx_edma->rx_buffers, skb);

        return true;
}

static struct ath_buf *ath_edma_get_next_rx_buf(struct ath_softc *sc,
                                                struct ath_rx_status *rs,
                                                enum ath9k_rx_qtype qtype)
{
        struct ath_rx_edma *rx_edma = &sc->rx.rx_edma[qtype];
        struct sk_buff *skb;
        struct ath_buf *bf;

        while (ath_edma_get_buffers(sc, qtype));
        skb = __skb_dequeue(&rx_edma->rx_buffers);
        if (!skb)
                return NULL;

        bf = SKB_CB_ATHBUF(skb);
        ath9k_hw_process_rxdesc_edma(sc->sc_ah, rs, skb->data);
        return bf;
}

static struct ath_buf *ath_get_next_rx_buf(struct ath_softc *sc,
                                           struct ath_rx_status *rs)
{
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        struct ath_desc *ds;
        struct ath_buf *bf;
        int ret;

        if (list_empty(&sc->rx.rxbuf)) {
                sc->rx.rxlink = NULL;
                return NULL;
        }

        bf = list_first_entry(&sc->rx.rxbuf, struct ath_buf, list);
        ds = bf->bf_desc;

        /*
         * Must provide the virtual address of the current
         * descriptor, the physical address, and the virtual
         * address of the next descriptor in the h/w chain.
         * This allows the HAL to look ahead to see if the
         * hardware is done with a descriptor by checking the
         * done bit in the following descriptor and the address
         * of the current descriptor the DMA engine is working
         * on.  All this is necessary because of our use of
         * a self-linked list to avoid rx overruns.
         */
        ret = ath9k_hw_rxprocdesc(ah, ds, rs, 0);
        if (ret == -EINPROGRESS) {
                struct ath_rx_status trs;
                struct ath_buf *tbf;
                struct ath_desc *tds;

                memset(&trs, 0, sizeof(trs));
                if (list_is_last(&bf->list, &sc->rx.rxbuf)) {
                        sc->rx.rxlink = NULL;
                        return NULL;
                }

                tbf = list_entry(bf->list.next, struct ath_buf, list);

                /*
                 * On some hardware the descriptor status words could
                 * get corrupted, including the done bit. Because of
                 * this, check if the next descriptor's done bit is
                 * set or not.
                 *
                 * If the next descriptor's done bit is set, the current
                 * descriptor has been corrupted. Force s/w to discard
                 * this descriptor and continue...
                 */

                tds = tbf->bf_desc;
                ret = ath9k_hw_rxprocdesc(ah, tds, &trs, 0);
                if (ret == -EINPROGRESS)
                        return NULL;
        }

        if (!bf->bf_mpdu)
                return bf;

        /*
         * Synchronize the DMA transfer with CPU before
         * 1. accessing the frame
         * 2. requeueing the same buffer to h/w
         */
        dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
                        common->rx_bufsize,
                        DMA_FROM_DEVICE);

        return bf;
}


int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
{
        struct ath_buf *bf;
        struct sk_buff *skb = NULL, *requeue_skb;
        struct ieee80211_rx_status *rxs;
        struct ath_hw *ah = sc->sc_ah;
        struct ath_common *common = ath9k_hw_common(ah);
        /*
         * The hw can techncically differ from common->hw when using ath9k
         * virtual wiphy so to account for that we iterate over the active
         * wiphys and find the appropriate wiphy and therefore hw.
         */
        struct ieee80211_hw *hw = NULL;
        struct ieee80211_hdr *hdr;
        int retval;
        bool decrypt_error = false;
        struct ath_rx_status rs;
        enum ath9k_rx_qtype qtype;
        bool edma = !!(ah->caps.hw_caps & ATH9K_HW_CAP_EDMA);
        int dma_type;

        if (edma)
                dma_type = DMA_FROM_DEVICE;
        else
                dma_type = DMA_BIDIRECTIONAL;

        qtype = hp ? ATH9K_RX_QUEUE_HP : ATH9K_RX_QUEUE_LP;
        spin_lock_bh(&sc->rx.rxbuflock);

        do {
                /* If handling rx interrupt and flush is in progress => exit */
                if ((sc->sc_flags & SC_OP_RXFLUSH) && (flush == 0))
                        break;

                memset(&rs, 0, sizeof(rs));
                if (edma)
                        bf = ath_edma_get_next_rx_buf(sc, &rs, qtype);
                else
                        bf = ath_get_next_rx_buf(sc, &rs);

                if (!bf)
                        break;

                skb = bf->bf_mpdu;
                if (!skb)
                        continue;

                hdr = (struct ieee80211_hdr *) skb->data;
                rxs =  IEEE80211_SKB_RXCB(skb);

                hw = ath_get_virt_hw(sc, hdr);

                ath_debug_stat_rx(sc, &rs);

                /*
                 * If we're asked to flush receive queue, directly
                 * chain it back at the queue without processing it.
                 */
                if (flush)
                        goto requeue;

                retval = ath9k_cmn_rx_skb_preprocess(common, hw, skb, &rs,
                                                     rxs, &decrypt_error);
                if (retval)
                        goto requeue;

                /* Ensure we always have an skb to requeue once we are done
                 * processing the current buffer's skb */
                requeue_skb = ath_rxbuf_alloc(common, common->rx_bufsize, GFP_ATOMIC);

                /* If there is no memory we ignore the current RX'd frame,
                 * tell hardware it can give us a new frame using the old
                 * skb and put it at the tail of the sc->rx.rxbuf list for
                 * processing. */
                if (!requeue_skb)
                        goto requeue;

                /* Unmap the frame */
                dma_unmap_single(sc->dev, bf->bf_buf_addr,
                                 common->rx_bufsize,
                                 dma_type);

                skb_put(skb, rs.rs_datalen + ah->caps.rx_status_len);
                if (ah->caps.rx_status_len)
                        skb_pull(skb, ah->caps.rx_status_len);

                ath9k_cmn_rx_skb_postprocess(common, skb, &rs,
                                             rxs, decrypt_error);

                /* We will now give hardware our shiny new allocated skb */
                bf->bf_mpdu = requeue_skb;
                bf->bf_buf_addr = dma_map_single(sc->dev, requeue_skb->data,
                                                 common->rx_bufsize,
                                                 dma_type);
                if (unlikely(dma_mapping_error(sc->dev,
                          bf->bf_buf_addr))) {
                        dev_kfree_skb_any(requeue_skb);
                        bf->bf_mpdu = NULL;
                        ath_print(common, ATH_DBG_FATAL,
                                  "dma_mapping_error() on RX\n");
                        ath_rx_send_to_mac80211(hw, sc, skb, rxs);
                        break;
                }
                bf->bf_dmacontext = bf->bf_buf_addr;

                /*
                 * change the default rx antenna if rx diversity chooses the
                 * other antenna 3 times in a row.
                 */
                if (sc->rx.defant != rs.rs_antenna) {
                        if (++sc->rx.rxotherant >= 3)
                                ath_setdefantenna(sc, rs.rs_antenna);
                } else {
                        sc->rx.rxotherant = 0;
                }

                if (unlikely(sc->ps_flags & (PS_WAIT_FOR_BEACON |
                                             PS_WAIT_FOR_CAB |
                                             PS_WAIT_FOR_PSPOLL_DATA)))
                        ath_rx_ps(sc, skb);

                ath_rx_send_to_mac80211(hw, sc, skb, rxs);

requeue:
                if (edma) {
                        list_add_tail(&bf->list, &sc->rx.rxbuf);
                        ath_rx_edma_buf_link(sc, qtype);
                } else {
                        list_move_tail(&bf->list, &sc->rx.rxbuf);
                        ath_rx_buf_link(sc, bf);
                }
        } while (1);

        spin_unlock_bh(&sc->rx.rxbuflock);

        return 0;
}