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mac80211: send (QoS) Null if no buffered frames 

For PS-poll, there's a possible race between
us expiring a frame and the station polling
for it -- send it a null frame in that case.

For uAPSD, the standard says that we have to
send a frame in each SP, so send null if we
don't have any other frames.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Johannes Berg 2011-09-29 16:04:34 +02:00 committed by John W. Linville
parent 47086fc51a
commit ce662b44ce
3 changed files with 94 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
net/mac80211/ieee80211_i.h
View File

@ -1272,6 +1272,7 @@ void mac80211_ev_michael_mic_failure(struct ieee80211_sub_if_data *sdata, int ke
struct ieee80211_hdr *hdr, const u8 *tsc,
gfp_t gfp);
void ieee80211_set_wmm_default(struct ieee80211_sub_if_data *sdata);
void ieee80211_xmit(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb);
void ieee80211_tx_skb(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb);
void ieee802_11_parse_elems(u8 *start, size_t len,
struct ieee802_11_elems *elems);

104
net/mac80211/sta_info.c
View File

@ -24,6 +24,7 @@
#include "sta_info.h"
#include "debugfs_sta.h"
#include "mesh.h"
#include "wme.h"
/**
* DOC: STA information lifetime rules
@ -247,10 +248,16 @@ static void sta_unblock(struct work_struct *wk)
ieee80211_sta_ps_deliver_wakeup(sta);
else if (test_and_clear_sta_flags(sta, WLAN_STA_PSPOLL)) {
clear_sta_flags(sta, WLAN_STA_PS_DRIVER);
local_bh_disable();
ieee80211_sta_ps_deliver_poll_response(sta);
local_bh_enable();
} else if (test_and_clear_sta_flags(sta, WLAN_STA_UAPSD)) {
clear_sta_flags(sta, WLAN_STA_PS_DRIVER);
local_bh_disable();
ieee80211_sta_ps_deliver_uapsd(sta);
local_bh_enable();
} else
clear_sta_flags(sta, WLAN_STA_PS_DRIVER);
}
@ -1157,6 +1164,70 @@ void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
}
static void ieee80211_send_null_response(struct ieee80211_sub_if_data *sdata,
struct sta_info *sta, int tid,
bool uapsd)
{
struct ieee80211_local *local = sdata->local;
struct ieee80211_qos_hdr *nullfunc;
struct sk_buff *skb;
int size = sizeof(*nullfunc);
__le16 fc;
bool qos = test_sta_flags(sta, WLAN_STA_WME);
struct ieee80211_tx_info *info;
if (qos) {
fc = cpu_to_le16(IEEE80211_FTYPE_DATA |
IEEE80211_STYPE_QOS_NULLFUNC |
IEEE80211_FCTL_FROMDS);
} else {
size -= 2;
fc = cpu_to_le16(IEEE80211_FTYPE_DATA |
IEEE80211_STYPE_NULLFUNC |
IEEE80211_FCTL_FROMDS);
}
skb = dev_alloc_skb(local->hw.extra_tx_headroom + size);
if (!skb)
return;
skb_reserve(skb, local->hw.extra_tx_headroom);
nullfunc = (void *) skb_put(skb, size);
nullfunc->frame_control = fc;
nullfunc->duration_id = 0;
memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
memcpy(nullfunc->addr2, sdata->vif.addr, ETH_ALEN);
memcpy(nullfunc->addr3, sdata->vif.addr, ETH_ALEN);
if (qos) {
skb->priority = tid;
skb_set_queue_mapping(skb, ieee802_1d_to_ac[tid]);
nullfunc->qos_ctrl = cpu_to_le16(tid);
if (uapsd)
nullfunc->qos_ctrl |=
cpu_to_le16(IEEE80211_QOS_CTL_EOSP);
}
info = IEEE80211_SKB_CB(skb);
/*
* Tell TX path to send this frame even though the
* STA may still remain is PS mode after this frame
* exchange.
*/
info->flags |= IEEE80211_TX_CTL_POLL_RESPONSE;
if (uapsd)
info->flags |= IEEE80211_TX_STATUS_EOSP |
IEEE80211_TX_CTL_REQ_TX_STATUS;
ieee80211_xmit(sdata, skb);
}
static void
ieee80211_sta_ps_deliver_response(struct sta_info *sta,
int n_frames, u8 ignored_acs,
@ -1228,19 +1299,28 @@ ieee80211_sta_ps_deliver_response(struct sta_info *sta,
}
if (!found) {
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
/*
* FIXME: This can be the result of a race condition between
* us expiring a frame and the station polling for it.
* Should we send it a null-func frame indicating we
* have nothing buffered for it?
*/
if (reason == IEEE80211_FRAME_RELEASE_PSPOLL)
printk(KERN_DEBUG "%s: STA %pM sent PS Poll even "
"though there are no buffered frames for it\n",
sdata->name, sta->sta.addr);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
int tid;
/*
* For PS-Poll, this can only happen due to a race condition
* when we set the TIM bit and the station notices it, but
* before it can poll for the frame we expire it.
*
* For uAPSD, this is said in the standard (11.2.1.5 h):
* At each unscheduled SP for a non-AP STA, the AP shall
* attempt to transmit at least one MSDU or MMPDU, but no
* more than the value specified in the Max SP Length field
* in the QoS Capability element from delivery-enabled ACs,
* that are destined for the non-AP STA.
*
* Since we have no other MSDU/MMPDU, transmit a QoS null frame.
*/
/* This will evaluate to 1, 3, 5 or 7. */
tid = 7 - ((ffs(~ignored_acs) - 1) << 1);
ieee80211_send_null_response(sdata, sta, tid,
reason == IEEE80211_FRAME_RELEASE_UAPSD);
return;
}

3
net/mac80211/tx.c
View File

@ -1520,8 +1520,7 @@ static int ieee80211_skb_resize(struct ieee80211_sub_if_data *sdata,
return 0;
}
static void ieee80211_xmit(struct ieee80211_sub_if_data *sdata,
struct sk_buff *skb)
void ieee80211_xmit(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
{
struct ieee80211_local *local = sdata->local;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);