carl9170: split up carl9170_handle_mpdu

PATCH Superseded Christian Lamparter 2 participants 3 messages Oct 20, 2012 – Oct 22, 2012 CARL9170 Linux community wireless driver

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Christian Lamparter

author maintainer

2012-10-20 18:00 UTC #0 lore raw

PATCH 1/1 carl9170: split up carl9170_handle_mpdu

carl9170_handle_mpdu is the final part of the rx path of the driver. It splits the raw data streams from the device into skb packets and passes them on to mac80211. As a result of continuous updates, it grew over the years when new code was added by the following commits:
- report A-MPDU status
- fix HT peer BA session corruption
- A-MPDU frame type filter
- ...

This patch splits the routine into two stages. The first stage only deals with the details about extracting and verifying the data from the incoming stream. Whereas the second stage packs it into skbs and passes it on to mac80211.

Reported-by Javier Lopez <[email protected]>

Signed-off-by Christian Lamparter <[email protected]>

---
 drivers/net/wireless/ath/carl9170/rx.c |   48 +++++++++++++++++++++++---------
 1 file changed, 35 insertions(+), 13 deletions(-)

drivers/net/wireless/ath/carl9170/rx.c +35 ~~-13~~

index 9cd93f1..887a4ae 100644
@@ -660,6 +660,38 @@ static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms,
 	return false;
 }
 
+static int carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len,
+				struct ieee80211_rx_status *status)
+{
+	struct sk_buff *skb;
+	int err = 0;
+
+	/* (driver) frame trap handler
+	 *
+	 * Because power-saving mode handing has to be implemented by
+	 * the driver/firmware. We have to check each incoming beacon
+	 * from the associated AP, if there's new data for us (either
+	 * broadcast/multicast or unicast) we have to react quickly.
+	 *
+	 * So, if you have you want to add additional frame trap
+	 * handlers, this would be the perfect place!
+	 */
+
+	carl9170_ps_beacon(ar, buf, len);
+
+	carl9170_ba_check(ar, buf, len);
+
+	skb = carl9170_rx_copy_data(buf, len);
+	if (skb) {
+		memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
+		ieee80211_rx(ar->hw, skb);
+	} else {
+		err = -ENOMEM;
+	}
+
+	return err;
+}
+
 /*
  * If the frame alignment is right (or the kernel has
  * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS), and there

@@ -669,14 +701,12 @@ static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms,
  * mode, and we need to observe the proper ordering,
  * this is non-trivial.
  */
-
-static void carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len)
+static void carl9170_rx_untie_data(struct ar9170 *ar, u8 *buf, int len)
 {
 	struct ar9170_rx_head *head;
 	struct ar9170_rx_macstatus *mac;
 	struct ar9170_rx_phystatus *phy = NULL;
 	struct ieee80211_rx_status status;
-	struct sk_buff *skb;
 	int mpdu_len;
 	u8 mac_status;

@@ -788,18 +818,10 @@ static void carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len)
 	if (phy)
 		carl9170_rx_phy_status(ar, phy, &status);
 
-	carl9170_ps_beacon(ar, buf, mpdu_len);
-
-	carl9170_ba_check(ar, buf, mpdu_len);
-
-	skb = carl9170_rx_copy_data(buf, mpdu_len);
-	if (!skb)
+	if (carl9170_handle_mpdu(ar, buf, mpdu_len, &status))
 		goto drop;
 
-	memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
-	ieee80211_rx(ar->hw, skb);
 	return;
-
 drop:
 	ar->rx_dropped++;
 }

@@ -851,7 +873,7 @@ static void __carl9170_rx(struct ar9170 *ar, u8 *buf, unsigned int len)
 	if (i == 12)
 		carl9170_rx_untie_cmds(ar, buf, len);
 	else
-		carl9170_handle_mpdu(ar, buf, len);
+		carl9170_rx_untie_data(ar, buf, len);
 }
 
 static void carl9170_rx_stream(struct ar9170 *ar, void *buf, unsigned int len)

Signature · 1 line

1.7.10.4

Julian Calaby

2012-10-21 22:20 UTC #1 lore raw

Hi Christian,

drivers/net/wireless/ath/carl9170/rx.c static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms, · line 667

Quoted 13 lines · Christian Lamparter

drivers/net/wireless/ath/carl9170/rx.c +5 -0

index 9cd93f1..887a4ae 100644
@@ -660,6 +660,38 @@ static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms,
        return false;
 }
 
+static int carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len,
+                               struct ieee80211_rx_status *status)
+{
+       struct sk_buff *skb;
+       int err = 0;

Personally, I hate the style of error handling where you have an explicit variable for a return value

Quoted 12 lines

drivers/net/wireless/ath/carl9170/rx.c +12 -0

+
+       /* (driver) frame trap handler
+        *
+        * Because power-saving mode handing has to be implemented by
+        * the driver/firmware. We have to check each incoming beacon
+        * from the associated AP, if there's new data for us (either
+        * broadcast/multicast or unicast) we have to react quickly.
+        *
+        * So, if you have you want to add additional frame trap
+        * handlers, this would be the perfect place!
+        */
+

drivers/net/wireless/ath/carl9170/rx.c static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms, · line 689

Quoted 10 lines

drivers/net/wireless/ath/carl9170/rx.c +10 -0

+       carl9170_ps_beacon(ar, buf, len);
+
+       carl9170_ba_check(ar, buf, len);
+
+       skb = carl9170_rx_copy_data(buf, len);
+       if (skb) {
+               memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
+               ieee80211_rx(ar->hw, skb);
+       } else {
+               err = -ENOMEM;

and then only set it

drivers/net/wireless/ath/carl9170/rx.c static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms, · line 692

Quoted 3 lines

drivers/net/wireless/ath/carl9170/rx.c +3 -0
+       }
+
+       return err;

immediately before you return it.

drivers/net/wireless/ath/carl9170/rx.c static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms, · line 694

Quoted 2 lines

drivers/net/wireless/ath/carl9170/rx.c +2 -0
+}
+

That said, this is my personal preference on the matter - however that style does make the "err" variable somewhat unnecessary as it's only used once. (yes, gcc will optimise it away, but that's not the point)

If you eliminated it, everything from if (skb) { on could be replaced by:

    if (!skb)
        return -ENOMEM;

    memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
    ieee80211_rx(ar->hw, skb);

    return 0;
}

which, IMHO, is much cleaner.

Thanks,

Signature · 5 lines

Julian Calaby

Email: [email protected]
Profile: http://www.google.com/profiles/julian.calaby/
.Plan: http://sites.google.com/site/juliancalaby/

Christian Lamparter

author maintainer

2012-10-22 13:01 UTC #2 lore raw

PATCH v2 1/1 carl9170: split up carl9170_handle_mpdu

Reported-by Javier Lopez <[email protected]>

Signed-off-by Christian Lamparter <[email protected]>

---
Hello Julian,

Quoted 14 lines · Julian Calaby

drivers/net/wireless/ath/carl9170/rx.c
Quoted 10 lines · Christian Lamparter
drivers/net/wireless/ath/carl9170/rx.c +7 -0
+static int carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len,
+                               struct ieee80211_rx_status *status)
+{
+       struct sk_buff *skb;
+       int err = 0;
[...]
+
+       /* (driver) frame trap handler
Personally, I hate the style of error handling where you have an explicit variable for a return value

Well the thinking behind "err" was that a trap handler might want to use it. But ATM noone handler which needs it has been implemented, so yeah why not remove it!

Regards,
Chr

---
 drivers/net/wireless/ath/carl9170/rx.c |   45 +++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 13 deletions(-)

drivers/net/wireless/ath/carl9170/rx.c +32 ~~-13~~

index 9cd93f1..6d22382 100644
@@ -660,6 +660,35 @@ static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms,
 	return false;
 }
 
+static int carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len,
+				struct ieee80211_rx_status *status)
+{
+	struct sk_buff *skb;
+
+	/* (driver) frame trap handler
+	 *
+	 * Because power-saving mode handing has to be implemented by
+	 * the driver/firmware. We have to check each incoming beacon
+	 * from the associated AP, if there's new data for us (either
+	 * broadcast/multicast or unicast) we have to react quickly.
+	 *
+	 * So, if you have you want to add additional frame trap
+	 * handlers, this would be the perfect place!
+	 */
+
+	carl9170_ps_beacon(ar, buf, len);
+
+	carl9170_ba_check(ar, buf, len);
+
+	skb = carl9170_rx_copy_data(buf, len);
+	if (!skb)
+		return -ENOMEM;
+
+	memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
+	ieee80211_rx(ar->hw, skb);
+	return 0;
+}
+
 /*
  * If the frame alignment is right (or the kernel has
  * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS), and there

@@ -669,14 +698,12 @@ static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms,
  * mode, and we need to observe the proper ordering,
  * this is non-trivial.
  */
-
-static void carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len)
+static void carl9170_rx_untie_data(struct ar9170 *ar, u8 *buf, int len)
 {
 	struct ar9170_rx_head *head;
 	struct ar9170_rx_macstatus *mac;
 	struct ar9170_rx_phystatus *phy = NULL;
 	struct ieee80211_rx_status status;
-	struct sk_buff *skb;
 	int mpdu_len;
 	u8 mac_status;

@@ -788,18 +815,10 @@ static void carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len)
 	if (phy)
 		carl9170_rx_phy_status(ar, phy, &status);
 
-	carl9170_ps_beacon(ar, buf, mpdu_len);
-
-	carl9170_ba_check(ar, buf, mpdu_len);
-
-	skb = carl9170_rx_copy_data(buf, mpdu_len);
-	if (!skb)
+	if (carl9170_handle_mpdu(ar, buf, mpdu_len, &status))
 		goto drop;
 
-	memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
-	ieee80211_rx(ar->hw, skb);
 	return;
-
 drop:
 	ar->rx_dropped++;
 }

@@ -851,7 +870,7 @@ static void __carl9170_rx(struct ar9170 *ar, u8 *buf, unsigned int len)
 	if (i == 12)
 		carl9170_rx_untie_cmds(ar, buf, len);
 	else
-		carl9170_handle_mpdu(ar, buf, len);
+		carl9170_rx_untie_data(ar, buf, len);
 }
 
 static void carl9170_rx_stream(struct ar9170 *ar, void *buf, unsigned int len)

Signature · 1 line

1.7.10.4