Requires software tx queueing support. frag_list support (for zero-copy)
is optional.
Signed-off-by: Felix Fietkau <[email protected]>
---
include/net/mac80211.h | 15 ++++
net/mac80211/agg-tx.c | 5 ++
net/mac80211/debugfs.c | 2 +
net/mac80211/ieee80211_i.h | 1 +
net/mac80211/tx.c | 167 +++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 190 insertions(+)
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 5714774..720ccb0 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -709,6 +709,7 @@ enum mac80211_tx_info_flags {
* @IEEE80211_TX_CTRL_PS_RESPONSE: This frame is a response to a poll
* frame (PS-Poll or uAPSD).
* @IEEE80211_TX_CTRL_RATE_INJECT: This frame is injected with rate information
+ * @IEEE80211_TX_CTRL_AMSDU: This frame is an A-MSDU frame
*
* These flags are used in tx_info->control.flags.
*/
@@ -716,6 +717,7 @@ enum mac80211_tx_control_flags {
IEEE80211_TX_CTRL_PORT_CTRL_PROTO = BIT(0),
IEEE80211_TX_CTRL_PS_RESPONSE = BIT(1),
IEEE80211_TX_CTRL_RATE_INJECT = BIT(2),
+ IEEE80211_TX_CTRL_AMSDU = BIT(3),
};
/*
@@ -1731,6 +1733,7 @@ struct ieee80211_sta_rates {
* size is min(max_amsdu_len, 7935) bytes.
* Both additional HT limits must be enforced by the low level driver.
* This is defined by the spec (IEEE 802.11-2012 section 8.3.2.2 NOTE 2).
+ * @max_rc_amsdu_len: Maximum A-MSDU size in bytes recommended by rate control.
* @txq: per-TID data TX queues (if driver uses the TXQ abstraction)
*/
struct ieee80211_sta {
@@ -1751,6 +1754,7 @@ struct ieee80211_sta {
bool mfp;
u8 max_amsdu_subframes;
u16 max_amsdu_len;
+ u16 max_rc_amsdu_len;
struct ieee80211_txq *txq[IEEE80211_NUM_TIDS];
@@ -1964,6 +1968,12 @@ struct ieee80211_txq {
* order and does not need to manage its own reorder buffer or BA session
* timeout.
*
+ * @IEEE80211_HW_TX_AMSDU: Hardware (or driver) supports software aggregated
+ * A-MSDU frames. Requires software tx queueing support.
+ *
+ * @IEEE80211_HW_TX_FRAG_LIST: Hardware (or driver) supports sending frag_list
+ * skbs, needed for zero-copy software A-MSDU.
+ *
* @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
*/
enum ieee80211_hw_flags {
@@ -2001,6 +2011,8 @@ enum ieee80211_hw_flags {
IEEE80211_HW_BEACON_TX_STATUS,
IEEE80211_HW_NEEDS_UNIQUE_STA_ADDR,
IEEE80211_HW_SUPPORTS_REORDERING_BUFFER,
+ IEEE80211_HW_TX_AMSDU,
+ IEEE80211_HW_TX_FRAG_LIST,
/* keep last, obviously */
NUM_IEEE80211_HW_FLAGS
@@ -2073,6 +2085,8 @@ enum ieee80211_hw_flags {
* size is smaller (an example is LinkSys WRT120N with FW v1.0.07
* build 002 Jun 18 2012).
*
+ * @max_tx_fragments: maximum fragments per (A-)MSDU.
+ *
* @offchannel_tx_hw_queue: HW queue ID to use for offchannel TX
* (if %IEEE80211_HW_QUEUE_CONTROL is set)
*
@@ -2127,6 +2141,7 @@ struct ieee80211_hw {
u8 max_rate_tries;
u8 max_rx_aggregation_subframes;
u8 max_tx_aggregation_subframes;
+ u8 max_tx_fragments;
u8 offchannel_tx_hw_queue;
u8 radiotap_mcs_details;
u16 radiotap_vht_details;
diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index 4932e9f..42fa810 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -935,6 +935,7 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
size_t len)
{
struct tid_ampdu_tx *tid_tx;
+ struct ieee80211_txq *txq;
u16 capab, tid;
u8 buf_size;
bool amsdu;
@@ -945,6 +946,10 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local,
buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;
buf_size = min(buf_size, local->hw.max_tx_aggregation_subframes);
+ txq = sta->sta.txq[tid];
+ if (!amsdu && txq)
+ set_bit(IEEE80211_TXQ_NO_AMSDU, &to_txq_info(txq)->flags);
+
mutex_lock(&sta->ampdu_mlme.mtx);
tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c
index e433d0c..847779d 100644
--- a/net/mac80211/debugfs.c
+++ b/net/mac80211/debugfs.c
@@ -127,6 +127,8 @@ static const char *hw_flag_names[NUM_IEEE80211_HW_FLAGS + 1] = {
FLAG(BEACON_TX_STATUS),
FLAG(NEEDS_UNIQUE_STA_ADDR),
FLAG(SUPPORTS_REORDERING_BUFFER),
+ FLAG(TX_AMSDU),
+ FLAG(TX_FRAG_LIST),
/* keep last for the build bug below */
(void *)0x1
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a49c103..e68d8db 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -799,6 +799,7 @@ struct mac80211_qos_map {
enum txq_info_flags {
IEEE80211_TXQ_STOP,
IEEE80211_TXQ_AMPDU,
+ IEEE80211_TXQ_NO_AMSDU,
};
struct txq_info {
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 7bb67fa9..a4108b7 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1324,6 +1324,10 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
out:
spin_unlock_bh(&txqi->queue.lock);
+ if (skb && skb_has_frag_list(skb) &&
+ !ieee80211_hw_check(&local->hw, TX_FRAG_LIST))
+ skb_linearize(skb);
+
return skb;
}
EXPORT_SYMBOL(ieee80211_tx_dequeue);
@@ -2766,6 +2770,165 @@ void ieee80211_clear_fast_xmit(struct sta_info *sta)
kfree_rcu(fast_tx, rcu_head);
}
+static int ieee80211_amsdu_pad(struct sk_buff *skb, int subframe_len)
+{
+ int amsdu_len = subframe_len + sizeof(struct ethhdr);
+ int padding = (4 - amsdu_len) & 3;
+
+ if (padding)
+ memset(skb_put(skb, padding), 0, padding);
+
+ return padding;
+}
+
+static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
+ struct ieee80211_fast_tx *fast_tx,
+ struct sk_buff *skb)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+ struct ieee80211_hdr *hdr;
+ struct ethhdr amsdu_hdr;
+ int hdr_len = fast_tx->hdr_len - sizeof(rfc1042_header);
+ int subframe_len = skb->len - hdr_len;
+ void *data;
+ u8 *qc;
+
+ if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
+ return false;
+
+ if (info->control.flags & IEEE80211_TX_CTRL_AMSDU)
+ return true;
+
+ if (skb_headroom(skb) < sizeof(amsdu_hdr) || skb_tailroom(skb) < 3) {
+ I802_DEBUG_INC(local->tx_expand_skb_head);
+
+ if (pskb_expand_head(skb, sizeof(amsdu_hdr), 3, GFP_ATOMIC)) {
+ wiphy_debug(local->hw.wiphy,
+ "failed to reallocate TX buffer\n");
+ return false;
+ }
+ }
+
+ subframe_len += ieee80211_amsdu_pad(skb, subframe_len);
+
+ amsdu_hdr.h_proto = cpu_to_be16(subframe_len);
+ memcpy(amsdu_hdr.h_source, skb->data + fast_tx->sa_offs, ETH_ALEN);
+ memcpy(amsdu_hdr.h_dest, skb->data + fast_tx->da_offs, ETH_ALEN);
+
+ data = skb_push(skb, sizeof(amsdu_hdr));
+ memmove(data, data + sizeof(amsdu_hdr), hdr_len);
+ memcpy(data + hdr_len, &amsdu_hdr, sizeof(amsdu_hdr));
+
+ hdr = data;
+ qc = ieee80211_get_qos_ctl(hdr);
+ *qc |= IEEE80211_QOS_CTL_A_MSDU_PRESENT;
+
+ info->control.flags |= IEEE80211_TX_CTRL_AMSDU;
+
+ return true;
+}
+
+static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
+ struct sta_info *sta,
+ struct ieee80211_fast_tx *fast_tx,
+ struct sk_buff *skb)
+{
+ struct ieee80211_local *local = sdata->local;
+ u8 tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
+ struct ieee80211_txq *txq = sta->sta.txq[tid];
+ struct txq_info *txqi;
+ struct sk_buff **frag_tail, *head;
+ int subframe_len = skb->len - ETH_ALEN;
+ u8 max_subframes = sta->sta.max_amsdu_subframes;
+ int max_frags = local->hw.max_tx_fragments;
+ int max_amsdu_len = sta->sta.max_amsdu_len;
+ __be16 len;
+ void *data;
+ bool ret = false;
+ int n = 1, nfrags;
+
+ if (!ieee80211_hw_check(&local->hw, TX_AMSDU))
+ return false;
+
+ if (!txq)
+ return false;
+
+ txqi = to_txq_info(txq);
+ if (test_bit(IEEE80211_TXQ_NO_AMSDU, &txqi->flags))
+ return false;
+
+ if (sta->sta.max_rc_amsdu_len)
+ max_amsdu_len = min_t(int, max_amsdu_len,
+ sta->sta.max_rc_amsdu_len);
+
+ spin_lock_bh(&txqi->queue.lock);
+
+ head = skb_peek_tail(&txqi->queue);
+ if (!head)
+ goto out;
+
+ if (skb->len + head->len > max_amsdu_len)
+ goto out;
+
+ /*
+ * HT A-MPDU limits maximum MPDU size to 4095 bytes. Since aggregation
+ * sessions are started/stopped without txq flush, use the limit here
+ * to avoid having to de-aggregate later.
+ */
+ if (skb->len + head->len > 4095 &&
+ !sta->sta.vht_cap.vht_supported)
+ goto out;
+
+ if (!ieee80211_amsdu_prepare_head(sdata, fast_tx, head))
+ goto out;
+
+ nfrags = 1 + skb_shinfo(skb)->nr_frags;
+ nfrags += 1 + skb_shinfo(head)->nr_frags;
+ frag_tail = &skb_shinfo(head)->frag_list;
+ while (*frag_tail) {
+ nfrags += 1 + skb_shinfo(*frag_tail)->nr_frags;
+ frag_tail = &(*frag_tail)->next;
+ n++;
+ }
+
+ if (max_subframes && n > max_subframes)
+ goto out;
+
+ if (max_frags && nfrags > max_frags)
+ goto out;
+
+ if (skb_headroom(skb) < 8 || skb_tailroom(skb) < 3) {
+ I802_DEBUG_INC(local->tx_expand_skb_head);
+
+ if (pskb_expand_head(skb, 8, 3, GFP_ATOMIC)) {
+ wiphy_debug(local->hw.wiphy,
+ "failed to reallocate TX buffer\n");
+ goto out;
+ }
+ }
+
+ subframe_len += ieee80211_amsdu_pad(skb, subframe_len);
+
+ ret = true;
+ data = skb_push(skb, ETH_ALEN + 2);
+ memmove(data, data + ETH_ALEN + 2, 2 * ETH_ALEN);
+
+ data += 2 * ETH_ALEN;
+ len = cpu_to_be16(subframe_len);
+ memcpy(data, &len, 2);
+ memcpy(data + 2, rfc1042_header, ETH_ALEN);
+
+ head->len += skb->len;
+ head->data_len += skb->len;
+ *frag_tail = skb;
+
+out:
+ spin_unlock_bh(&txqi->queue.lock);
+
+ return ret;
+}
+
static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
struct net_device *dev, struct sta_info *sta,
struct ieee80211_fast_tx *fast_tx,
@@ -2820,6 +2983,10 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
ieee80211_tx_stats(dev, skb->len + extra_head);
+ if ((hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) &&
+ ieee80211_amsdu_aggregate(sdata, sta, fast_tx, skb))
+ return true;
+
/* will not be crypto-handled beyond what we do here, so use false
* as the may-encrypt argument for the resize to not account for
* more room than we already have in 'extra_head'
--
2.2.2
On 2016-02-23 12:25, Johannes Berg wrote:
> On Thu, 2016-02-18 at 19:39 +0100, Felix Fietkau wrote:
>> Requires software tx queueing support. frag_list support (for zero-
>> copy) is optional.
>
> "optional" ;-)
>
>> @@ -1751,6 +1754,7 @@ struct ieee80211_sta {
>> bool mfp;
>> u8 max_amsdu_subframes;
>> u16 max_amsdu_len;
>> + u16 max_rc_amsdu_len;
>
> I may have missed this, but I didn't see you initialize this to
> something. I think that's probably a bad idea, since you've now created
> a situation in which a driver wanting to use txq support needs to also
> use minstrel or update this field...
It's initialized to 0 by default, in which case it does not limit the
A-MSDU size. The driver does not need to set it, but it really should.
> Apart from that, I'm not sure that having a field here that works like
> this is a good idea at all - all the other fields in the vicinity kinda
> go from mac80211 to the driver, where here you have something that
> potentially goes from the driver to mac80211. Perhaps we can find a
> better way of doing this?
Didn't find a better place to put it. Got any ideas?
>> + * @IEEE80211_HW_TX_AMSDU: Hardware (or driver) supports software
>> aggregated
>> + * A-MSDU frames. Requires software tx queueing support.
>
> Or at least document that it also requires integration with the
> max_rc_amsdu_len thing.
Will do.
>> + * @max_tx_fragments: maximum fragments per (A-)MSDU.
>
> "fragments" is a bit unclear - I guess this should refer to fraglist
> length only? Or is it meant to apply as a limit to the sum of pieces in
> the fraglist? I think that should be clarified.
Sum of 1 (head) + n_frags for each skb in the fraglist.
>> + txq = sta->sta.txq[tid];
>> + if (!amsdu && txq)
>> + set_bit(IEEE80211_TXQ_NO_AMSDU, &to_txq_info(txq)-
>> >flags);
>
> Did you intentionally not clear this on aggregation stop?
Yes. If A-MSDU in A-MPDU is not supported, dealing with starting and
stopping of A-MPDU sessions leaves all kinds of nasty corner cases
(since the txq is not flushed between sessions). In that case it's
better to just leave it disabled from that point on.
>> + if (skb_headroom(skb) < sizeof(amsdu_hdr) ||
>> skb_tailroom(skb) < 3) {
>> + I802_DEBUG_INC(local->tx_expand_skb_head);
>> +
>> + if (pskb_expand_head(skb, sizeof(amsdu_hdr), 3,
>> GFP_ATOMIC)) {
>
> You should be able to precalculate the amount of padding needed based
> on the length of the skb, so why statically use 3 here?
I guess I forgot to change that after I got the code working.
>> + if (skb_headroom(skb) < 8 || skb_tailroom(skb) < 3) {
>> + I802_DEBUG_INC(local->tx_expand_skb_head);
>> +
>> + if (pskb_expand_head(skb, 8, 3, GFP_ATOMIC)) {
>
> similarly here? Where does the 8 come from?
rfc1042_header + A-MSDU length field.
>> @@ -2820,6 +2983,10 @@ static bool ieee80211_xmit_fast(struct
>> ieee80211_sub_if_data *sdata,
>>
>> ieee80211_tx_stats(dev, skb->len + extra_head);
>>
>> + if ((hdr->frame_control &
>> cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) &&
>> + ieee80211_amsdu_aggregate(sdata, sta, fast_tx, skb))
>> + return true;
>
> Only on xmit_fast?
Yes. I'm relying on fast_tx fields to simplify dealing with headers and
to avoid adding extra checks for all kinds of stuff like no software
crypto, which ieee80211_check_fast_xmit already handles.
- Felix
On Thu, 2016-02-18 at 19:39 +0100, Felix Fietkau wrote:
> Requires software tx queueing support. frag_list support (for zero-
> copy)
> is optional.
>
Come to think of it, a commit message that explains what it does and
how it works would be nice :)
johannes
On 2016-02-23 14:05, Johannes Berg wrote:
>> Yes. If A-MSDU in A-MPDU is not supported, dealing with starting and
>> stopping of A-MPDU sessions leaves all kinds of nasty corner cases
>> (since the txq is not flushed between sessions). In that case it's
>> better to just leave it disabled from that point on.
>
> Fair enough. You should be able to deal with it with the SSN, but that
> might be difficult.
>
> Actually, mac80211 on its own assigns the seqno so frames already on
> the txq would not become part of the session, so we should be OK
> without much effort?
seqno is assigned on txq dequeue, not enqueue.
- Felix
Prevents excessive A-MSDU aggregation at low data rates or bad
conditions.
Signed-off-by: Felix Fietkau <[email protected]>
---
net/mac80211/rc80211_minstrel_ht.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 3928dbd..ad8859c 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -882,6 +882,39 @@ minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
ratetbl->rate[offset].flags = flags;
}
+static int
+minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)
+{
+ int group = mi->max_prob_rate / MCS_GROUP_RATES;
+ const struct mcs_group *g = &minstrel_mcs_groups[group];
+ int rate = mi->max_prob_rate % MCS_GROUP_RATES;
+
+ /* Disable A-MSDU if max_prob_rate is bad */
+ if (mi->groups[group].rates[rate].prob_ewma < MINSTREL_FRAC(50, 100))
+ return 1;
+
+ /* If the rate is slower than single-stream MCS1, make A-MSDU limit small */
+ if (g->duration[rate] > MCS_DURATION(1, 0, 52))
+ return 500;
+
+ /*
+ * If the rate is slower than single-stream MCS4, limit A-MSDU to usual
+ * data packet size
+ */
+ if (g->duration[rate] > MCS_DURATION(1, 0, 104))
+ return 1500;
+
+ /*
+ * If the rate is slower than single-stream MCS7, limit A-MSDU to twice
+ * the usual data packet size
+ */
+ if (g->duration[rate] > MCS_DURATION(1, 0, 260))
+ return 3000;
+
+ /* unlimited */
+ return 0;
+}
+
static void
minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
{
@@ -906,6 +939,7 @@ minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
}
+ mi->sta->max_rc_amsdu_len = minstrel_ht_get_max_amsdu_len(mi);
rates->rate[i].idx = -1;
rate_control_set_rates(mp->hw, mi->sta, rates);
}
--
2.2.2
On Tue, 2016-02-23 at 13:12 +0100, Felix Fietkau wrote:
>
> It's initialized to 0 by default, in which case it does not limit the
> A-MSDU size. The driver does not need to set it, but it really
> should.
Right, but this is problematic as Emmanuel had pointed out, when
scaling down you run into problems. Not sure we want that as the
default when the driver doesn't do anything?
Documenting it as we discussed should be good enough though I guess.
> > Apart from that, I'm not sure that having a field here that works
> > like
> > this is a good idea at all - all the other fields in the vicinity
> > kinda
> > go from mac80211 to the driver, where here you have something that
> > potentially goes from the driver to mac80211. Perhaps we can find a
> > better way of doing this?
> Didn't find a better place to put it. Got any ideas?
Not off the top of my head, sorry.
> > > + * @max_tx_fragments: maximum fragments per (A-)MSDU.
> >
> > "fragments" is a bit unclear - I guess this should refer to
> > fraglist
> > length only? Or is it meant to apply as a limit to the sum of
> > pieces in
> > the fraglist? I think that should be clarified.
> Sum of 1 (head) + n_frags for each skb in the fraglist.
Clarify the comment? :)
> Yes. If A-MSDU in A-MPDU is not supported, dealing with starting and
> stopping of A-MPDU sessions leaves all kinds of nasty corner cases
> (since the txq is not flushed between sessions). In that case it's
> better to just leave it disabled from that point on.
Fair enough. You should be able to deal with it with the SSN, but that
might be difficult.
Actually, mac80211 on its own assigns the seqno so frames already on
the txq would not become part of the session, so we should be OK
without much effort?
> Yes. I'm relying on fast_tx fields to simplify dealing with headers
> and to avoid adding extra checks for all kinds of stuff like no
> software crypto, which ieee80211_check_fast_xmit already handles.
>
Ok, makes sense.
johannes
On Thu, 2016-02-18 at 19:39 +0100, Felix Fietkau wrote:
> Requires software tx queueing support. frag_list support (for zero-
> copy) is optional.
"optional" ;-)
> @@ -1751,6 +1754,7 @@ struct ieee80211_sta {
> bool mfp;
> u8 max_amsdu_subframes;
> u16 max_amsdu_len;
> + u16 max_rc_amsdu_len;
I may have missed this, but I didn't see you initialize this to
something. I think that's probably a bad idea, since you've now created
a situation in which a driver wanting to use txq support needs to also
use minstrel or update this field...
Apart from that, I'm not sure that having a field here that works like
this is a good idea at all - all the other fields in the vicinity kinda
go from mac80211 to the driver, where here you have something that
potentially goes from the driver to mac80211. Perhaps we can find a
better way of doing this?
> + * @IEEE80211_HW_TX_AMSDU: Hardware (or driver) supports software
> aggregated
> + * A-MSDU frames. Requires software tx queueing support.
Or at least document that it also requires integration with the
max_rc_amsdu_len thing.
> + * @max_tx_fragments: maximum fragments per (A-)MSDU.
"fragments" is a bit unclear - I guess this should refer to fraglist
length only? Or is it meant to apply as a limit to the sum of pieces in
the fraglist? I think that should be clarified.
> + txq = sta->sta.txq[tid];
> + if (!amsdu && txq)
> + set_bit(IEEE80211_TXQ_NO_AMSDU, &to_txq_info(txq)-
> >flags);
Did you intentionally not clear this on aggregation stop?
> + if (skb_headroom(skb) < sizeof(amsdu_hdr) ||
> skb_tailroom(skb) < 3) {
> + I802_DEBUG_INC(local->tx_expand_skb_head);
> +
> + if (pskb_expand_head(skb, sizeof(amsdu_hdr), 3,
> GFP_ATOMIC)) {
You should be able to precalculate the amount of padding needed based
on the length of the skb, so why statically use 3 here?
> + if (skb_headroom(skb) < 8 || skb_tailroom(skb) < 3) {
> + I802_DEBUG_INC(local->tx_expand_skb_head);
> +
> + if (pskb_expand_head(skb, 8, 3, GFP_ATOMIC)) {
similarly here? Where does the 8 come from?
> @@ -2820,6 +2983,10 @@ static bool ieee80211_xmit_fast(struct
> ieee80211_sub_if_data *sdata,
>
> ieee80211_tx_stats(dev, skb->len + extra_head);
>
> + if ((hdr->frame_control &
> cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) &&
> + ieee80211_amsdu_aggregate(sdata, sta, fast_tx, skb))
> + return true;
Only on xmit_fast?
johannes