On Fri, Feb 4, 2011 at 6:42 PM, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote:
> On Fri, 2011-02-04 at 14:08 +0100, Johannes Berg wrote:
>> > diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
>> > index e059b3a..45f736e 100644
>> > --- a/net/mac80211/mlme.c
>> > +++ b/net/mac80211/mlme.c
>> > @@ -727,13 +727,17 @@ 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))) {
>> > + ifmgd->flags |= IEEE80211_STA_PS_PENDING;
>> > ieee80211_send_nullfunc(local, sdata, 1);
>> > + }
>> >
>> > if (!((local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) &&
>> > (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)) ||
>> > - (ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED)) {
>> > + ((ifmgd->flags & IEEE80211_STA_NULLFUNC_ACKED) &&
>> > + ifmgd->flags & IEEE80211_STA_PS_PENDING)) {
>> > ifmgd->flags &= ~IEEE80211_STA_NULLFUNC_ACKED;
>> > + ifmgd->flags &= ~IEEE80211_STA_PS_PENDING;
>> > local->hw.conf.flags |= IEEE80211_CONF_PS;
>> > ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
>> > }
>> > diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
>> > index 8fbbc7a..e1c2256 100644
>> > --- a/net/mac80211/tx.c
>> > +++ b/net/mac80211/tx.c
>> > @@ -185,6 +185,7 @@ ieee80211_tx_h_dynamic_ps(struct ieee80211_tx_data *tx)
>> > {
>> > struct ieee80211_local *local = tx->local;
>> > struct ieee80211_if_managed *ifmgd;
>> > + struct ieee80211_hdr *hdr;
>> >
>> > /* driver doesn't support power save */
>> > if (!(local->hw.flags & IEEE80211_HW_SUPPORTS_PS))
>> > @@ -233,6 +234,13 @@ ieee80211_tx_h_dynamic_ps(struct ieee80211_tx_data *tx)
>> > && skb_get_queue_mapping(tx->skb) == 0)
>> > return TX_CONTINUE;
>> >
>> > + hdr = (struct ieee80211_hdr *)tx->skb->data;
>> > +
>> > + if (!(ieee80211_is_nullfunc(hdr->frame_control) &&
>> > + ieee80211_has_pm(hdr->frame_control)) &&
>> > + (ifmgd->flags & IEEE80211_STA_PS_PENDING))
>> > + ifmgd->flags &= ~IEEE80211_STA_PS_PENDING;
>> > +
>> > if (local->hw.conf.flags & IEEE80211_CONF_PS) {
>>
>> I don't see how this patch helps anything. Should the last line I quoted
>> be replaced instead by checking if PS was requested? We used to not wait
>> for the ACK -- so waiting for the ACK broke this.
>
> Ok maybe I see how this helps -- but I don't think it's race-free. When
> the PS-pending flag is cleared here, the code above that checks it might
> already have passed and be in the driver callback or so.
When it is in the driver callback, IEEE80211_CONF_PS would have been
set and when this is set, ieee80211_tx_h_dynamic_ps will disable PS
and there wont be any discrepancy in power save states between AP and
the station.
Vivek.
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