ath: add common ath_rxbuf_alloc() and make ath9k use it

Turns out ath5k and ath9k can share the same helper to
allocates RX skbs. We allocate skbs aligned to the cache line
size. This requirement seems to have come from AR5210; when
this was not done it seems sometimes we'd get bogus data. I'm
also told it may have been a performance enhancement
consideration. In the end I can't be sure we can remove this
on new hardware so just keep this and start sharing it through
ath.ko.

Make ath9k start using this, ath5k is next.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 36 deletions

diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 1a08c694fe5d..61dbdd227444 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -100,38 +100,6 @@ static u64 ath_extend_tsf(struct ath_softc *sc, u32 rstamp)
 	return (tsf & ~0x7fff) | rstamp;
 }
 
-static struct sk_buff *ath_rxbuf_alloc(struct ath_softc *sc, u32 len, gfp_t gfp_mask)
-{
-	struct sk_buff *skb;
-	u32 off;
-
-	/*
-	 * Cache-line-align.  This is important (for the
-	 * 5210 at least) as not doing so causes bogus data
-	 * in rx'd frames.
-	 */
-
-	/* Note: the kernel can allocate a value greater than
-	 * what we ask it to give us. We really only need 4 KB as that
-	 * is this hardware supports and in fact we need at least 3849
-	 * as that is the MAX AMSDU size this hardware supports.
-	 * Unfortunately this means we may get 8 KB here from the
-	 * kernel... and that is actually what is observed on some
-	 * systems :( */
-	skb = __dev_alloc_skb(len + sc->cachelsz - 1, gfp_mask);
-	if (skb != NULL) {
-		off = ((unsigned long) skb->data) % sc->cachelsz;
-		if (off != 0)
-			skb_reserve(skb, sc->cachelsz - off);
-	} else {
-		DPRINTF(sc, ATH_DBG_FATAL,
-			"skbuff alloc of size %u failed\n", len);
-		return NULL;
-	}
-
-	return skb;
-}
-
 /*
  * For Decrypt or Demic errors, we only mark packet status here and always push
  * up the frame up to let mac80211 handle the actual error case, be it no
@@ -336,10 +304,10 @@ int ath_rx_init(struct ath_softc *sc, int nbufs)
 	spin_lock_init(&sc->rx.rxbuflock);
 
 	sc->rx.bufsize = roundup(IEEE80211_MAX_MPDU_LEN,
-				 min(sc->cachelsz, (u16)64));
+				 min(sc->common.cachelsz, (u16)64));
 
 	DPRINTF(sc, ATH_DBG_CONFIG, "cachelsz %u rxbufsize %u\n",
-		sc->cachelsz, sc->rx.bufsize);
+		sc->common.cachelsz, sc->rx.bufsize);
 
 	/* Initialize rx descriptors */
 
@@ -352,7 +320,7 @@ int ath_rx_init(struct ath_softc *sc, int nbufs)
 	}
 
 	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
-		skb = ath_rxbuf_alloc(sc, sc->rx.bufsize, GFP_KERNEL);
+		skb = ath_rxbuf_alloc(&sc->common, sc->rx.bufsize, GFP_KERNEL);
 		if (skb == NULL) {
 			error = -ENOMEM;
 			goto err;
@@ -777,7 +745,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
 
 		/* Ensure we always have an skb to requeue once we are done
 		 * processing the current buffer's skb */
-		requeue_skb = ath_rxbuf_alloc(sc, sc->rx.bufsize, GFP_ATOMIC);
+		requeue_skb = ath_rxbuf_alloc(&sc->common, sc->rx.bufsize, GFP_ATOMIC);
 
 		/* If there is no memory we ignore the current RX'd frame,
 		 * tell hardware it can give us a new frame using the old