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    Subject[PATCH 4.9 079/222] ath9k: Fix a locking bug in ath9k_add_interface()
    Date
    From: Dan Carpenter <dan.carpenter@oracle.com>

    [ Upstream commit 461cf036057477805a8a391e5fd0f5264a5e56a8 ]

    We tried to revert commit d9c52fd17cb4 ("ath9k: fix tx99 with monitor
    mode interface") but accidentally missed part of the locking change.

    The lock has to be held earlier so that we're holding it when we do
    "sc->tx99_vif = vif;" and also there in the current code there is a
    stray unlock before we have taken the lock.

    Fixes: 6df0580be8bc ("ath9k: add back support for using active monitor interfaces for tx99")
    Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
    Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/wireless/ath/ath9k/main.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
    index f6151a00041d6..abc997427bae5 100644
    --- a/drivers/net/wireless/ath/ath9k/main.c
    +++ b/drivers/net/wireless/ath/ath9k/main.c
    @@ -1249,6 +1249,7 @@ static int ath9k_add_interface(struct ieee80211_hw *hw,
    struct ath_vif *avp = (void *)vif->drv_priv;
    struct ath_node *an = &avp->mcast_node;

    + mutex_lock(&sc->mutex);
    if (IS_ENABLED(CONFIG_ATH9K_TX99)) {
    if (sc->cur_chan->nvifs >= 1) {
    mutex_unlock(&sc->mutex);
    @@ -1257,8 +1258,6 @@ static int ath9k_add_interface(struct ieee80211_hw *hw,
    sc->tx99_vif = vif;
    }

    - mutex_lock(&sc->mutex);
    -
    ath_dbg(common, CONFIG, "Attach a VIF of type: %d\n", vif->type);
    sc->cur_chan->nvifs++;

    --
    2.20.1


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