On Fri, Jan 27, 2012 at 11:02 AM, Helmut Schaa
<helmut.schaa@xxxxxxxxxxxxxx> wrote:
> If the driver blocked this specific STA with the help of
> ieee80211_sta_block_awake we won't clear WLAN_STA_PS_STA later but
> still decrement num_sta_ps. Hence, the next data frame from this
> STA will trigger ap_sta_ps_end again and also decrement num_sta_ps
> again leading to an incorrect num_sta_ps counter.
>
> This can result in problems with powersaving clients not waking up
> from PS because the TIM calculation might be skipped due to the
> incorrect num_sta_ps counter.
John, I need to send a v2 for this since it introduces a warning:
net/mac80211/rx.c: In function ‘ap_sta_ps_end’:
net/mac80211/rx.c:1148:32: warning: unused variable ‘sdata’ [-Wunused-variable]
Helmut
> Signed-off-by: Helmut Schaa <helmut.schaa@xxxxxxxxxxxxxx>
> ---
> net/mac80211/rx.c | 1 -
> net/mac80211/sta_info.c | 4 +++-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
> index 3567586..f89617a 100644
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -1147,7 +1147,6 @@ static void ap_sta_ps_end(struct sta_info *sta)
> {
> struct ieee80211_sub_if_data *sdata = sta->sdata;
>
> - atomic_dec(&sdata->bss->num_sta_ps);
>
> #ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
> printk(KERN_DEBUG "%s: STA %pM aid %d exits power save mode\n",
> diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
> index 70a0de3..92b894c 100644
> --- a/net/mac80211/sta_info.c
> +++ b/net/mac80211/sta_info.c
> @@ -1007,9 +1007,11 @@ EXPORT_SYMBOL(ieee80211_find_sta);
> static void clear_sta_ps_flags(void *_sta)
> {
> struct sta_info *sta = _sta;
> + struct ieee80211_sub_if_data *sdata = sta->sdata;
>
> clear_sta_flag(sta, WLAN_STA_PS_DRIVER);
> - clear_sta_flag(sta, WLAN_STA_PS_STA);
> + if (test_and_clear_sta_flag(sta, WLAN_STA_PS_STA))
> + atomic_dec(&sdata->bss->num_sta_ps);
> }
>
> /* powersave support code */
> --
> 1.7.7
>
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