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    Subject[PATCH 3.8 055/124] b43: Fix lockdep splat
    Date
    3.8.13.18 -stable review patch.  If anyone has any objections, please let me know.

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

    From: Larry Finger <Larry.Finger@lwfinger.net>

    commit 09164043f63c947a49797750a09ca1cd7c31108e upstream.

    In https://bugzilla.kernel.org/show_bug.cgi?id=67561, a locking dependency is reported
    when b43 is used with hostapd, and rfkill is used to kill the radio output.

    The lockdep splat (in part) is as follows:

    ======================================================
    [ INFO: possible circular locking dependency detected ]
    3.12.0 #1 Not tainted
    -------------------------------------------------------
    rfkill/10040 is trying to acquire lock:
    (rtnl_mutex){+.+.+.}, at: [<ffffffff8146f282>] rtnl_lock+0x12/0x20

    but task is already holding lock:
    (rfkill_global_mutex){+.+.+.}, at: [<ffffffffa04832ca>] rfkill_fop_write+0x6a/0x170 [rfkill]

    --snip--

    Chain exists of:
    rtnl_mutex --> misc_mtx --> rfkill_global_mutex

    The fix is to move the initialization of the hardware random number generator
    outside the code range covered by the rtnl_mutex.

    Reported-by: yury <urykhy@gmail.com>
    Tested-by: yury <urykhy@gmail.com>
    Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
    Signed-off-by: John W. Linville <linville@tuxdriver.com>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    drivers/net/wireless/b43/main.c | 17 +++++++++++------
    1 file changed, 11 insertions(+), 6 deletions(-)

    diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c
    index 911c4c0..bb421be 100644
    --- a/drivers/net/wireless/b43/main.c
    +++ b/drivers/net/wireless/b43/main.c
    @@ -2415,6 +2415,7 @@ error:

    static int b43_one_core_attach(struct b43_bus_dev *dev, struct b43_wl *wl);
    static void b43_one_core_detach(struct b43_bus_dev *dev);
    +static int b43_rng_init(struct b43_wl *wl);

    static void b43_request_firmware(struct work_struct *work)
    {
    @@ -2466,6 +2467,10 @@ start_ieee80211:
    goto err_one_core_detach;
    wl->hw_registred = true;
    b43_leds_register(wl->current_dev);
    +
    + /* Register HW RNG driver */
    + b43_rng_init(wl);
    +
    goto out;

    err_one_core_detach:
    @@ -4630,9 +4635,6 @@ static void b43_wireless_core_exit(struct b43_wldev *dev)
    if (!dev || b43_status(dev) != B43_STAT_INITIALIZED)
    return;

    - /* Unregister HW RNG driver */
    - b43_rng_exit(dev->wl);
    -
    b43_set_status(dev, B43_STAT_UNINIT);

    /* Stop the microcode PSM. */
    @@ -4775,9 +4777,6 @@ static int b43_wireless_core_init(struct b43_wldev *dev)

    b43_set_status(dev, B43_STAT_INITIALIZED);

    - /* Register HW RNG driver */
    - b43_rng_init(dev->wl);
    -
    out:
    return err;

    @@ -5438,6 +5437,9 @@ static void b43_bcma_remove(struct bcma_device *core)

    b43_one_core_detach(wldev->dev);

    + /* Unregister HW RNG driver */
    + b43_rng_exit(wl);
    +
    b43_leds_unregister(wl);

    ieee80211_free_hw(wl->hw);
    @@ -5515,6 +5517,9 @@ static void b43_ssb_remove(struct ssb_device *sdev)

    b43_one_core_detach(dev);

    + /* Unregister HW RNG driver */
    + b43_rng_exit(wl);
    +
    if (list_empty(&wl->devlist)) {
    b43_leds_unregister(wl);
    /* Last core on the chip unregistered.
    --
    1.8.3.2


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