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    Subject[18/34] iwlwifi: fix scan abort
    2.6.32-stable review patch.  If anyone has any objections, please let us know.

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

    From: Stanislaw Gruszka <sgruszka@redhat.com>

    commit d28232b461b8d54b09e59325dbac8b0913ce2049 upstream.

    Fix possible double priv->mutex lock introduced by commit
    a69b03e941abae00380fc6bc1877fb797a1b31e6
    "iwlwifi: cancel scan watchdog in iwl_bg_abort_scan" .
    We can not call cancel_delayed_work_sync(&priv->scan_check) with
    priv->mutex locked because workqueue function iwl_bg_scan_check()
    take that lock internally.

    We do not need to synchronize when canceling priv->scan_check work.
    We can avoid races (sending double abort command or send no
    command at all) using STATUS_SCAN_ABORT bit. Moreover
    current iwl_bg_scan_check() code seems to be broken, as
    we should not send abort commands when currently aborting.

    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/iwlwifi/iwl-scan.c | 18 ++++++++----------
    1 file changed, 8 insertions(+), 10 deletions(-)

    --- a/drivers/net/wireless/iwlwifi/iwl-scan.c
    +++ b/drivers/net/wireless/iwlwifi/iwl-scan.c
    @@ -497,11 +497,10 @@ void iwl_bg_scan_check(struct work_struc
    return;

    mutex_lock(&priv->mutex);
    - if (test_bit(STATUS_SCANNING, &priv->status) ||
    - test_bit(STATUS_SCAN_ABORTING, &priv->status)) {
    - IWL_DEBUG_SCAN(priv, "Scan completion watchdog resetting "
    - "adapter (%dms)\n",
    - jiffies_to_msecs(IWL_SCAN_CHECK_WATCHDOG));
    + if (test_bit(STATUS_SCANNING, &priv->status) &&
    + !test_bit(STATUS_SCAN_ABORTING, &priv->status)) {
    + IWL_DEBUG_SCAN(priv, "Scan completion watchdog (%dms)\n",
    + jiffies_to_msecs(IWL_SCAN_CHECK_WATCHDOG));

    if (!test_bit(STATUS_EXIT_PENDING, &priv->status))
    iwl_send_scan_abort(priv);
    @@ -797,12 +796,11 @@ void iwl_bg_abort_scan(struct work_struc
    !test_bit(STATUS_GEO_CONFIGURED, &priv->status))
    return;

    - mutex_lock(&priv->mutex);
    -
    - cancel_delayed_work_sync(&priv->scan_check);
    - set_bit(STATUS_SCAN_ABORTING, &priv->status);
    - iwl_send_scan_abort(priv);
    + cancel_delayed_work(&priv->scan_check);

    + mutex_lock(&priv->mutex);
    + if (test_bit(STATUS_SCAN_ABORTING, &priv->status))
    + iwl_send_scan_abort(priv);
    mutex_unlock(&priv->mutex);
    }
    EXPORT_SYMBOL(iwl_bg_abort_scan);



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