diff options
author | Johannes Berg <johannes@sipsolutions.net> | 2008-02-20 22:59:33 (GMT) |
---|---|---|
committer | John W. Linville <linville@tuxdriver.com> | 2008-02-29 20:41:32 (GMT) |
commit | d46e144b65bf053b25d134ec9f52a38e63e04bb4 (patch) | |
tree | 95a3e4ea7660511375f71c54335045a5d1441b1a /net/mac80211/ieee80211.c | |
parent | d97cf01576e1867d26b5c8de360380f815a1b7df (diff) | |
download | linux-fsl-qoriq-d46e144b65bf053b25d134ec9f52a38e63e04bb4.tar.xz |
mac80211: rework TX filtered frame code
This reworks the code for TX filtered frames, splitting it out to
a new function to handle those cases, making the clear instruction
a flag and renaming a few things to be easier to understand and
less Atheros hardware specific. Finally, it also makes the comments
explain more.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net/mac80211/ieee80211.c')
-rw-r--r-- | net/mac80211/ieee80211.c | 121 |
1 files changed, 79 insertions, 42 deletions
diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c index 7df1479..a00858d 100644 --- a/net/mac80211/ieee80211.c +++ b/net/mac80211/ieee80211.c @@ -1178,6 +1178,77 @@ no_key: } } +static void ieee80211_handle_filtered_frame(struct ieee80211_local *local, + struct sta_info *sta, + struct sk_buff *skb, + struct ieee80211_tx_status *status) +{ + sta->tx_filtered_count++; + + /* + * Clear the TX filter mask for this STA when sending the next + * packet. If the STA went to power save mode, this will happen + * happen when it wakes up for the next time. + */ + sta->flags |= WLAN_STA_CLEAR_PS_FILT; + + /* + * This code races in the following way: + * + * (1) STA sends frame indicating it will go to sleep and does so + * (2) hardware/firmware adds STA to filter list, passes frame up + * (3) hardware/firmware processes TX fifo and suppresses a frame + * (4) we get TX status before having processed the frame and + * knowing that the STA has gone to sleep. + * + * This is actually quite unlikely even when both those events are + * processed from interrupts coming in quickly after one another or + * even at the same time because we queue both TX status events and + * RX frames to be processed by a tasklet and process them in the + * same order that they were received or TX status last. Hence, there + * is no race as long as the frame RX is processed before the next TX + * status, which drivers can ensure, see below. + * + * Note that this can only happen if the hardware or firmware can + * actually add STAs to the filter list, if this is done by the + * driver in response to set_tim() (which will only reduce the race + * this whole filtering tries to solve, not completely solve it) + * this situation cannot happen. + * + * To completely solve this race drivers need to make sure that they + * (a) don't mix the irq-safe/not irq-safe TX status/RX processing + * functions and + * (b) always process RX events before TX status events if ordering + * can be unknown, for example with different interrupt status + * bits. + */ + if (sta->flags & WLAN_STA_PS && + skb_queue_len(&sta->tx_filtered) < STA_MAX_TX_BUFFER) { + ieee80211_remove_tx_extra(local, sta->key, skb, + &status->control); + skb_queue_tail(&sta->tx_filtered, skb); + return; + } + + if (!(sta->flags & WLAN_STA_PS) && + !(status->control.flags & IEEE80211_TXCTL_REQUEUE)) { + /* Software retry the packet once */ + status->control.flags |= IEEE80211_TXCTL_REQUEUE; + ieee80211_remove_tx_extra(local, sta->key, skb, + &status->control); + dev_queue_xmit(skb); + return; + } + + if (net_ratelimit()) + printk(KERN_DEBUG "%s: dropped TX filtered frame, " + "queue_len=%d PS=%d @%lu\n", + wiphy_name(local->hw.wiphy), + skb_queue_len(&sta->tx_filtered), + !!(sta->flags & WLAN_STA_PS), jiffies); + dev_kfree_skb(skb); +} + void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb, struct ieee80211_tx_status *status) { @@ -1202,11 +1273,16 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb, sta = sta_info_get(local, hdr->addr1); if (sta) { if (sta->flags & WLAN_STA_PS) { - /* The STA is in power save mode, so assume + /* + * The STA is in power save mode, so assume * that this TX packet failed because of that. */ status->excessive_retries = 0; status->flags |= IEEE80211_TX_STATUS_TX_FILTERED; + ieee80211_handle_filtered_frame(local, sta, + skb, status); + sta_info_put(sta); + return; } sta_info_put(sta); } @@ -1216,47 +1292,8 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb, struct sta_info *sta; sta = sta_info_get(local, hdr->addr1); if (sta) { - sta->tx_filtered_count++; - - /* Clear the TX filter mask for this STA when sending - * the next packet. If the STA went to power save mode, - * this will happen when it is waking up for the next - * time. */ - sta->clear_dst_mask = 1; - - /* TODO: Is the WLAN_STA_PS flag always set here or is - * the race between RX and TX status causing some - * packets to be filtered out before 80211.o gets an - * update for PS status? This seems to be the case, so - * no changes are likely to be needed. */ - if (sta->flags & WLAN_STA_PS && - skb_queue_len(&sta->tx_filtered) < - STA_MAX_TX_BUFFER) { - ieee80211_remove_tx_extra(local, sta->key, - skb, - &status->control); - skb_queue_tail(&sta->tx_filtered, skb); - } else if (!(sta->flags & WLAN_STA_PS) && - !(status->control.flags & IEEE80211_TXCTL_REQUEUE)) { - /* Software retry the packet once */ - status->control.flags |= IEEE80211_TXCTL_REQUEUE; - ieee80211_remove_tx_extra(local, sta->key, - skb, - &status->control); - dev_queue_xmit(skb); - } else { - if (net_ratelimit()) { - printk(KERN_DEBUG "%s: dropped TX " - "filtered frame queue_len=%d " - "PS=%d @%lu\n", - wiphy_name(local->hw.wiphy), - skb_queue_len( - &sta->tx_filtered), - !!(sta->flags & WLAN_STA_PS), - jiffies); - } - dev_kfree_skb(skb); - } + ieee80211_handle_filtered_frame(local, sta, skb, + status); sta_info_put(sta); return; } |