[PATCH 1/3] ath10k: Ensure there are no stale ar->txqs entries.

[Michal Kazior]

On 19 August 2016 at 03:26,  <greearb at candelatech.com> wrote:
> From: Ben Greear <greearb at candelatech.com>
>
> I was seeing kernel crashes due to accessing freed memory
> while debugging a 9984 firmware that was crashing often.
>
> This patch fixes the crashes.  I am not certain if there
> is a better way or not.
>
> Signed-off-by: Ben Greear <greearb at candelatech.com>
> ---
>  drivers/net/wireless/ath/ath10k/mac.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
> index 5659ef1..916119c 100644
> --- a/drivers/net/wireless/ath/ath10k/mac.c
> +++ b/drivers/net/wireless/ath/ath10k/mac.c
> @@ -4172,8 +4172,10 @@ static void ath10k_mac_txq_init(struct ieee80211_txq *txq)
>  static void ath10k_mac_txq_unref(struct ath10k *ar, struct ieee80211_txq *txq)
>  {
>         struct ath10k_txq *artxq = (void *)txq->drv_priv;
> +       struct ath10k_txq *tmp, *walker;
>         struct ath10k_skb_cb *cb;
>         struct sk_buff *msdu;
> +       struct ieee80211_txq *txq_tmp;
>         int msdu_id;
>
>         if (!txq)
> @@ -4182,6 +4184,14 @@ static void ath10k_mac_txq_unref(struct ath10k *ar, struct ieee80211_txq *txq)
>         spin_lock_bh(&ar->txqs_lock);
>         if (!list_empty(&artxq->list))
>                 list_del_init(&artxq->list);
> +
> +       /* Remove from ar->txqs in case it still exists there. */
> +       list_for_each_entry_safe(walker, tmp, &ar->txqs, list) {
> +               txq_tmp = container_of((void *)walker, struct ieee80211_txq,
> +                                      drv_priv);
> +               if (txq_tmp == txq)
> +                       list_del(&walker->list);
> +       }

How could this even happen? All artxq->list accesses (add/del) are
protected by txqs_lock so this shouldn't happen, no?

Do you perhaps have the logic around txqs reworked in your tree?


Michał