On Wed, 2011-02-23 at 13:04 +0530, Vivek Natarajan wrote:
> There is a race on sending a data frame before the tx completion
> of nullfunc frame for enabling power save. As the data quickly
> follows the nullfunc frame, the AP thinks that the station is out
> of power save and continues to send the frames. Whereas in the
> station, the nullfunc ack will be processed after the tx completion
> of data frame and mac80211 goes to powersave. Thus the power
> save state mismatch between the station and the AP causes some
> data loss and some applications fail because of that. This patch
> fixes this issue.
>
> Signed-off-by: Vivek Natarajan <vnatarajan@xxxxxxxxxxx>
> ---
> net/mac80211/mlme.c | 14 +++++++++++++-
> net/mac80211/status.c | 2 --
> 2 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index 7b3f9df..abb0116 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -738,9 +738,19 @@ void ieee80211_dynamic_ps_enable_work(struct work_struct *work)
> return;
>
> if ((local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK) &&
> - (!(ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)))
> + (!(ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED))) {
> + netif_tx_stop_all_queues(sdata->dev);
> + /*
> + * Flush all the frames queued in the driver before
> + * going to power save
> + */
> + drv_flush(local, false);
> ieee80211_send_nullfunc(local, sdata, 1);
>
> + /* Flush once again to get the tx status of nullfunc frame */
> + drv_flush(local, false);
> + }
> +
> if (!((local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) &&
> (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)) ||
> (ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)) {
> @@ -748,6 +758,8 @@ void ieee80211_dynamic_ps_enable_work(struct work_struct *work)
> local->hw.conf.flags |= IEEE80211_CONF_PS;
> ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
> }
> +
> + netif_tx_start_all_queues(sdata->dev);
> }
>
> void ieee80211_dynamic_ps_timer(unsigned long data)
> diff --git a/net/mac80211/status.c b/net/mac80211/status.c
> index 010a559..8651851 100644
> --- a/net/mac80211/status.c
> +++ b/net/mac80211/status.c
> @@ -318,8 +318,6 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
> if (info->flags & IEEE80211_TX_STAT_ACK) {
> local->ps_sdata->u.mgd.flags |=
> IEEE80211_STA_NULLFUNC_ACKED;
> - ieee80211_queue_work(&local->hw,
> - &local->dynamic_ps_enable_work);
Is the patch still correct if you don't remove this? I realise it won't
usually be necessary, but I think we don't flush the TX status tasklet
on flush right now so in theory there could be a race there that this
code would clean up after, right?
johannes
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