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Commit ce662b44 authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

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: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 47086fc5

net/mac80211/ieee80211_i.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

net/mac80211/sta_info.c

+90 −10
Original line number Diff line number Diff line
@@ -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

		int tid;



		/*

		 * 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?

		 * 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.

		 */

		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 */



		/* 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;

	}

net/mac80211/tx.c

+1 −2
Original line number Diff line number Diff line
@@ -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);