mac80211: move TX info into skb->cb

This patch converts mac80211 and all drivers to have transmit
information and status in skb->cb rather than allocating extra
memory for it and copying all the data around. To make it fit,
a union is used where only data that is necessary for all steps
is kept outside of the union.

A number of fixes were done by Ivo, as well as the rt2x00 part
of this patch.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 43 insertions, 135 deletions

diff --git a/drivers/net/wireless/zd1211rw/zd_mac.c b/drivers/net/wireless/zd1211rw/zd_mac.c
index 99c508c09e5..edb1aefb4ad 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.c
+++ b/drivers/net/wireless/zd1211rw/zd_mac.c
@@ -224,36 +224,6 @@ out:
         return r;
 }
 
-/**
- * clear_tx_skb_control_block - clears the control block of tx skbuffs
- * @skb: a &struct sk_buff pointer
- *
- * This clears the control block of skbuff buffers, which were transmitted to
- * the device. Notify that the function is not thread-safe, so prevent
- * multiple calls.
- */
-static void clear_tx_skb_control_block(struct sk_buff *skb)
-{
-        struct zd_tx_skb_control_block *cb =
-                (struct zd_tx_skb_control_block *)skb->cb;
-
-        kfree(cb->control);
-        cb->control = NULL;
-}
-
-/**
- * kfree_tx_skb - frees a tx skbuff
- * @skb: a &struct sk_buff pointer
- *
- * Frees the tx skbuff. Frees also the allocated control structure in the
- * control block if necessary.
- */
-static void kfree_tx_skb(struct sk_buff *skb)
-{
-        clear_tx_skb_control_block(skb);
-        dev_kfree_skb_any(skb);
-}
-
 static void zd_op_stop(struct ieee80211_hw *hw)
 {
         struct zd_mac *mac = zd_hw_mac(hw);
@@ -276,40 +246,15 @@ static void zd_op_stop(struct ieee80211_hw *hw)
 
 
         while ((skb = skb_dequeue(ack_wait_queue)))
-                kfree_tx_skb(skb);
-}
-
-/**
- * init_tx_skb_control_block - initializes skb control block
- * @skb: a &sk_buff pointer
- * @dev: pointer to the mac80221 device
- * @control: mac80211 tx control applying for the frame in @skb
- *
- * Initializes the control block of the skbuff to be transmitted.
- */
-static int init_tx_skb_control_block(struct sk_buff *skb,
-                                     struct ieee80211_hw *hw,
-                                     struct ieee80211_tx_control *control)
-{
-        struct zd_tx_skb_control_block *cb =
-                (struct zd_tx_skb_control_block *)skb->cb;
-
-        ZD_ASSERT(sizeof(*cb) <= sizeof(skb->cb));
-        memset(cb, 0, sizeof(*cb));
-        cb->hw= hw;
-        cb->control = kmalloc(sizeof(*control), GFP_ATOMIC);
-        if (cb->control == NULL)
-                return -ENOMEM;
-        memcpy(cb->control, control, sizeof(*control));
-
-        return 0;
+                dev_kfree_skb_any(skb);
 }
 
 /**
  * tx_status - reports tx status of a packet if required
  * @hw - a &struct ieee80211_hw pointer
  * @skb - a sk-buffer
- * @status - the tx status of the packet without control information
+ * @flags: extra flags to set in the TX status info
+ * @ackssi: ACK signal strength
  * @success - True for successfull transmission of the frame
  *
  * This information calls ieee80211_tx_status_irqsafe() if required by the
@@ -319,18 +264,17 @@ static int init_tx_skb_control_block(struct sk_buff *skb,
  * If no status information has been requested, the skb is freed.
  */
 static void tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
-                      struct ieee80211_tx_status *status,
-                      bool success)
+                      u32 flags, int ackssi, bool success)
 {
-        struct zd_tx_skb_control_block *cb = (struct zd_tx_skb_control_block *)
-                skb->cb;
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+
+        memset(&info->status, 0, sizeof(info->status));
 
-        ZD_ASSERT(cb->control != NULL);
-        memcpy(&status->control, cb->control, sizeof(status->control));
         if (!success)
-                status->excessive_retries = 1;
-        clear_tx_skb_control_block(skb);
-        ieee80211_tx_status_irqsafe(hw, skb, status);
+                info->status.excessive_retries = 1;
+        info->flags |= flags;
+        info->status.ack_signal = ackssi;
+        ieee80211_tx_status_irqsafe(hw, skb);
 }
 
 /**
@@ -345,15 +289,12 @@ void zd_mac_tx_failed(struct ieee80211_hw *hw)
 {
         struct sk_buff_head *q = &zd_hw_mac(hw)->ack_wait_queue;
         struct sk_buff *skb;
-        struct ieee80211_tx_status status;
 
         skb = skb_dequeue(q);
         if (skb == NULL)
                 return;
 
-        memset(&status, 0, sizeof(status));
-
-        tx_status(hw, skb, &status, 0);
+        tx_status(hw, skb, 0, 0, 0);
 }
 
 /**
@@ -368,28 +309,20 @@ void zd_mac_tx_failed(struct ieee80211_hw *hw)
  */
 void zd_mac_tx_to_dev(struct sk_buff *skb, int error)
 {
-        struct zd_tx_skb_control_block *cb =
-                (struct zd_tx_skb_control_block *)skb->cb;
-        struct ieee80211_hw *hw = cb->hw;
-
-        if (likely(cb->control)) {
-                skb_pull(skb, sizeof(struct zd_ctrlset));
-                if (unlikely(error ||
-                    (cb->control->flags & IEEE80211_TXCTL_NO_ACK)))
-                {
-                        struct ieee80211_tx_status status;
-                        memset(&status, 0, sizeof(status));
-                        tx_status(hw, skb, &status, !error);
-                } else {
-                        struct sk_buff_head *q =
-                                &zd_hw_mac(hw)->ack_wait_queue;
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+        struct ieee80211_hw *hw = info->driver_data[0];
 
-                        skb_queue_tail(q, skb);
-                        while (skb_queue_len(q) > ZD_MAC_MAX_ACK_WAITERS)
-                                zd_mac_tx_failed(hw);
-                }
+        skb_pull(skb, sizeof(struct zd_ctrlset));
+        if (unlikely(error ||
+            (info->flags & IEEE80211_TX_CTL_NO_ACK))) {
+                tx_status(hw, skb, 0, 0, !error);
         } else {
-                kfree_tx_skb(skb);
+                struct sk_buff_head *q =
+                        &zd_hw_mac(hw)->ack_wait_queue;
+
+                skb_queue_tail(q, skb);
+                while (skb_queue_len(q) > ZD_MAC_MAX_ACK_WAITERS)
+                        zd_mac_tx_failed(hw);
         }
 }
 
@@ -454,7 +387,7 @@ static void cs_set_control(struct zd_mac *mac, struct zd_ctrlset *cs,
         cs->control = 0;
 
         /* First fragment */
-        if (flags & IEEE80211_TXCTL_FIRST_FRAGMENT)
+        if (flags & IEEE80211_TX_CTL_FIRST_FRAGMENT)
                 cs->control |= ZD_CS_NEED_RANDOM_BACKOFF;
 
         /* Multicast */
@@ -466,10 +399,10 @@ static void cs_set_control(struct zd_mac *mac, struct zd_ctrlset *cs,
             (IEEE80211_FTYPE_CTL|IEEE80211_STYPE_PSPOLL))
                 cs->control |= ZD_CS_PS_POLL_FRAME;
 
-        if (flags & IEEE80211_TXCTL_USE_RTS_CTS)
+        if (flags & IEEE80211_TX_CTL_USE_RTS_CTS)
                 cs->control |= ZD_CS_RTS;
 
-        if (flags & IEEE80211_TXCTL_USE_CTS_PROTECT)
+        if (flags & IEEE80211_TX_CTL_USE_CTS_PROTECT)
                 cs->control |= ZD_CS_SELF_CTS;
 
         /* FIXME: Management frame? */
@@ -516,8 +449,7 @@ void zd_mac_config_beacon(struct ieee80211_hw *hw, struct sk_buff *beacon)
 }
 
 static int fill_ctrlset(struct zd_mac *mac,
-                        struct sk_buff *skb,
-                        struct ieee80211_tx_control *control)
+                        struct sk_buff *skb)
 {
         int r;
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
@@ -526,18 +458,19 @@ static int fill_ctrlset(struct zd_mac *mac,
         struct ieee80211_rate *txrate;
         struct zd_ctrlset *cs = (struct zd_ctrlset *)
                 skb_push(skb, sizeof(struct zd_ctrlset));
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 
         ZD_ASSERT(frag_len <= 0xffff);
 
-        txrate = ieee80211_get_tx_rate(mac->hw, control);
+        txrate = ieee80211_get_tx_rate(mac->hw, info);
 
         cs->modulation = txrate->hw_value;
-        if (control->flags & IEEE80211_TXCTL_SHORT_PREAMBLE)
+        if (info->flags & IEEE80211_TX_CTL_SHORT_PREAMBLE)
                 cs->modulation = txrate->hw_value_short;
 
         cs->tx_length = cpu_to_le16(frag_len);
 
-        cs_set_control(mac, cs, hdr, control->flags);
+        cs_set_control(mac, cs, hdr, info->flags);
 
         packet_length = frag_len + sizeof(struct zd_ctrlset) + 10;
         ZD_ASSERT(packet_length <= 0xffff);
@@ -582,24 +515,21 @@ static int fill_ctrlset(struct zd_mac *mac,
  * control block of the skbuff will be initialized. If necessary the incoming
  * mac80211 queues will be stopped.
  */
-static int zd_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb,
-                     struct ieee80211_tx_control *control)
+static int zd_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 {
         struct zd_mac *mac = zd_hw_mac(hw);
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
         int r;
 
-        r = fill_ctrlset(mac, skb, control);
+        r = fill_ctrlset(mac, skb);
         if (r)
                 return r;
 
-        r = init_tx_skb_control_block(skb, hw, control);
-        if (r)
-                return r;
+        info->driver_data[0] = hw;
+
         r = zd_usb_tx(&mac->chip.usb, skb);
-        if (r) {
-                clear_tx_skb_control_block(skb);
+        if (r)
                 return r;
-        }
         return 0;
 }
 
@@ -637,13 +567,8 @@ static int filter_ack(struct ieee80211_hw *hw, struct ieee80211_hdr *rx_hdr,
                 tx_hdr = (struct ieee80211_hdr *)skb->data;
                 if (likely(!compare_ether_addr(tx_hdr->addr2, rx_hdr->addr1)))
                 {
-                        struct ieee80211_tx_status status;
-
-                        memset(&status, 0, sizeof(status));
-                        status.flags = IEEE80211_TX_STATUS_ACK;
-                        status.ack_signal = stats->signal;
                         __skb_unlink(skb, q);
-                        tx_status(hw, skb, &status, 1);
+                        tx_status(hw, skb, IEEE80211_TX_STAT_ACK, stats->signal, 1);
                         goto out;
                 }
         }
@@ -947,8 +872,7 @@ static void zd_op_bss_info_changed(struct ieee80211_hw *hw,
 }
 
 static int zd_op_beacon_update(struct ieee80211_hw *hw,
-                               struct sk_buff *skb,
-                               struct ieee80211_tx_control *ctl)
+                               struct sk_buff *skb)
 {
         struct zd_mac *mac = zd_hw_mac(hw);
         zd_mac_config_beacon(hw, skb);
diff --git a/drivers/net/wireless/zd1211rw/zd_mac.h b/drivers/net/wireless/zd1211rw/zd_mac.h
index 71170244d2c..18c1d56d3dd 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.h
+++ b/drivers/net/wireless/zd1211rw/zd_mac.h
@@ -149,22 +149,6 @@ struct housekeeping {
         struct delayed_work link_led_work;
 };
 
-/**
- * struct zd_tx_skb_control_block - control block for tx skbuffs
- * @control: &struct ieee80211_tx_control pointer
- * @context: context pointer
- *
- * This structure is used to fill the cb field in an &sk_buff to transmit.
- * The control field is NULL, if there is no requirement from the mac80211
- * stack to report about the packet ACK. This is the case if the flag
- * IEEE80211_TXCTL_NO_ACK is not set in &struct ieee80211_tx_control.
- */
-struct zd_tx_skb_control_block {
-        struct ieee80211_tx_control *control;
-        struct ieee80211_hw *hw;
-        void *context;
-};
-
 #define ZD_MAC_STATS_BUFFER_SIZE 16
 
 #define ZD_MAC_MAX_ACK_WAITERS 10
diff --git a/drivers/net/wireless/zd1211rw/zd_usb.c b/drivers/net/wireless/zd1211rw/zd_usb.c
index 12e24f04ddd..c8a0b34aecc 100644
--- a/drivers/net/wireless/zd1211rw/zd_usb.c
+++ b/drivers/net/wireless/zd1211rw/zd_usb.c
@@ -869,7 +869,7 @@ static void tx_urb_complete(struct urb *urb)
 {
         int r;
         struct sk_buff *skb;
-        struct zd_tx_skb_control_block *cb;
+        struct ieee80211_tx_info *info;
         struct zd_usb *usb;
 
         switch (urb->status) {
@@ -893,8 +893,8 @@ free_urb:
          * grab 'usb' pointer before handing off the skb (since
          * it might be freed by zd_mac_tx_to_dev or mac80211)
          */
-        cb = (struct zd_tx_skb_control_block *)skb->cb;
-        usb = &zd_hw_mac(cb->hw)->chip.usb;
+        info = IEEE80211_SKB_CB(skb);
+        usb = &zd_hw_mac(info->driver_data[0])->chip.usb;
         zd_mac_tx_to_dev(skb, urb->status);
         free_tx_urb(usb, urb);
         tx_dec_submitted_urbs(usb);