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    Subject[89/89] iwlegacy: fix channel switch locking
    2.6.39-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Stanislaw Gruszka <sgruszka@redhat.com>

    commit 51e65257142a87fe46a1ce5c35c86c5baf012614 upstream.

    We use priv->mutex to avoid race conditions between chswitch_done()
    and mac_channel_switch(), when marking channel switch in
    progress. But chswitch_done() can be called in atomic context
    from rx_csa() or with mutex already taken from commit_rxon().

    To fix remove mutex from chswitch_done() and use atomic bitops
    for marking channel switch pending.

    Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
    Signed-off-by: John W. Linville <linville@tuxdriver.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    drivers/net/wireless/iwlegacy/iwl-4965.c | 9 ++------
    drivers/net/wireless/iwlegacy/iwl-core.c | 30 +++++++++++----------------
    drivers/net/wireless/iwlegacy/iwl-core.h | 2 -
    drivers/net/wireless/iwlegacy/iwl-dev.h | 13 -----------
    drivers/net/wireless/iwlegacy/iwl4965-base.c | 19 +++++++++--------
    5 files changed, 28 insertions(+), 45 deletions(-)

    --- a/drivers/net/wireless/iwlegacy/iwl-4965.c
    +++ b/drivers/net/wireless/iwlegacy/iwl-4965.c
    @@ -1218,10 +1218,10 @@ static int iwl4965_commit_rxon(struct iw
    * receive commit_rxon request
    * abort any previous channel switch if still in process
    */
    - if (priv->switch_rxon.switch_in_progress &&
    - (priv->switch_rxon.channel != ctx->staging.channel)) {
    + if (test_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status) &&
    + (priv->switch_channel != ctx->staging.channel)) {
    IWL_DEBUG_11H(priv, "abort channel switch on %d\n",
    - le16_to_cpu(priv->switch_rxon.channel));
    + le16_to_cpu(priv->switch_channel));
    iwl_legacy_chswitch_done(priv, false);
    }

    @@ -1404,9 +1404,6 @@ static int iwl4965_hw_channel_switch(str
    return rc;
    }

    - priv->switch_rxon.channel = cmd.channel;
    - priv->switch_rxon.switch_in_progress = true;
    -
    return iwl_legacy_send_cmd_pdu(priv,
    REPLY_CHANNEL_SWITCH, sizeof(cmd), &cmd);
    }
    --- a/drivers/net/wireless/iwlegacy/iwl-core.c
    +++ b/drivers/net/wireless/iwlegacy/iwl-core.c
    @@ -862,12 +862,8 @@ void iwl_legacy_chswitch_done(struct iwl
    if (test_bit(STATUS_EXIT_PENDING, &priv->status))
    return;

    - if (priv->switch_rxon.switch_in_progress) {
    + if (test_and_clear_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status))
    ieee80211_chswitch_done(ctx->vif, is_success);
    - mutex_lock(&priv->mutex);
    - priv->switch_rxon.switch_in_progress = false;
    - mutex_unlock(&priv->mutex);
    - }
    }
    EXPORT_SYMBOL(iwl_legacy_chswitch_done);

    @@ -879,19 +875,19 @@ void iwl_legacy_rx_csa(struct iwl_priv *
    struct iwl_rxon_context *ctx = &priv->contexts[IWL_RXON_CTX_BSS];
    struct iwl_legacy_rxon_cmd *rxon = (void *)&ctx->active;

    - if (priv->switch_rxon.switch_in_progress) {
    - if (!le32_to_cpu(csa->status) &&
    - (csa->channel == priv->switch_rxon.channel)) {
    - rxon->channel = csa->channel;
    - ctx->staging.channel = csa->channel;
    - IWL_DEBUG_11H(priv, "CSA notif: channel %d\n",
    - le16_to_cpu(csa->channel));
    - iwl_legacy_chswitch_done(priv, true);
    - } else {
    - IWL_ERR(priv, "CSA notif (fail) : channel %d\n",
    + if (!test_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status))
    + return;
    +
    + if (!le32_to_cpu(csa->status) && csa->channel == priv->switch_channel) {
    + rxon->channel = csa->channel;
    + ctx->staging.channel = csa->channel;
    + IWL_DEBUG_11H(priv, "CSA notif: channel %d\n",
    le16_to_cpu(csa->channel));
    - iwl_legacy_chswitch_done(priv, false);
    - }
    + iwl_legacy_chswitch_done(priv, true);
    + } else {
    + IWL_ERR(priv, "CSA notif (fail) : channel %d\n",
    + le16_to_cpu(csa->channel));
    + iwl_legacy_chswitch_done(priv, false);
    }
    }
    EXPORT_SYMBOL(iwl_legacy_rx_csa);
    --- a/drivers/net/wireless/iwlegacy/iwl-core.h
    +++ b/drivers/net/wireless/iwlegacy/iwl-core.h
    @@ -561,7 +561,7 @@ void iwl_legacy_free_geos(struct iwl_pri
    #define STATUS_SCAN_HW 15
    #define STATUS_POWER_PMI 16
    #define STATUS_FW_ERROR 17
    -
    +#define STATUS_CHANNEL_SWITCH_PENDING 18

    static inline int iwl_legacy_is_ready(struct iwl_priv *priv)
    {
    --- a/drivers/net/wireless/iwlegacy/iwl-dev.h
    +++ b/drivers/net/wireless/iwlegacy/iwl-dev.h
    @@ -854,17 +854,6 @@ struct traffic_stats {
    };

    /*
    - * iwl_switch_rxon: "channel switch" structure
    - *
    - * @ switch_in_progress: channel switch in progress
    - * @ channel: new channel
    - */
    -struct iwl_switch_rxon {
    - bool switch_in_progress;
    - __le16 channel;
    -};
    -
    -/*
    * schedule the timer to wake up every UCODE_TRACE_PERIOD milliseconds
    * to perform continuous uCode event logging operation if enabled
    */
    @@ -1115,7 +1104,7 @@ struct iwl_priv {

    struct iwl_rxon_context contexts[NUM_IWL_RXON_CTX];

    - struct iwl_switch_rxon switch_rxon;
    + __le16 switch_channel;

    /* 1st responses from initialize and runtime uCode images.
    * _4965's initialize alive response contains some calibration data. */
    --- a/drivers/net/wireless/iwlegacy/iwl4965-base.c
    +++ b/drivers/net/wireless/iwlegacy/iwl4965-base.c
    @@ -2851,16 +2851,13 @@ void iwl4965_mac_channel_switch(struct i
    goto out_exit;

    if (test_bit(STATUS_EXIT_PENDING, &priv->status) ||
    - test_bit(STATUS_SCANNING, &priv->status))
    + test_bit(STATUS_SCANNING, &priv->status) ||
    + test_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status))
    goto out_exit;

    if (!iwl_legacy_is_associated_ctx(ctx))
    goto out_exit;

    - /* channel switch in progress */
    - if (priv->switch_rxon.switch_in_progress == true)
    - goto out_exit;
    -
    mutex_lock(&priv->mutex);
    if (priv->cfg->ops->lib->set_channel_switch) {

    @@ -2910,16 +2907,20 @@ void iwl4965_mac_channel_switch(struct i
    * at this point, staging_rxon has the
    * configuration for channel switch
    */
    + set_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status);
    + priv->switch_channel = cpu_to_le16(ch);
    if (priv->cfg->ops->lib->set_channel_switch(priv,
    - ch_switch))
    - priv->switch_rxon.switch_in_progress = false;
    + ch_switch)) {
    + clear_bit(STATUS_CHANNEL_SWITCH_PENDING,
    + &priv->status);
    + priv->switch_channel = 0;
    + ieee80211_chswitch_done(ctx->vif, false);
    + }
    }
    }
    out:
    mutex_unlock(&priv->mutex);
    out_exit:
    - if (!priv->switch_rxon.switch_in_progress)
    - ieee80211_chswitch_done(ctx->vif, false);
    IWL_DEBUG_MAC80211(priv, "leave\n");
    }




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