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ath9k: correct expected max RX buffer size

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We should only tell the hardware its capable of DMA'ing
to us only what we asked dev_alloc_skb(). Prior to this
it is possible a large RX'd frame could have corrupted
DMA data but for us but we were saved only because we
were previously also pci_map_single()'ing the same large
value. The issue prior to this though was we were unmapping
a smaller amount which the prior DMA patch fixed.

Signed-off-by: Bennyam Malavazi <Bennyam.Malavazi@atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Luis R. Rodriguez 2008-11-20 17:15:13 -08:00 committed by John W. Linville
parent ca0c7e5101
commit b4b6cda229
1 changed files with 11 additions and 2 deletions
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13
drivers/net/wireless/ath9k/recv.c
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@ -49,10 +49,12 @@ static void ath_rx_buf_link(struct ath_softc *sc, struct ath_buf *bf)
ASSERT(skb != NULL);
ds->ds_vdata = skb->data;
/* setup rx descriptors */
/* setup rx descriptors. The sc_rxbufsize here tells the harware
* how much data it can DMA to us and that we are prepared
* to process */
ath9k_hw_setuprxdesc(ah,
ds,
skb_tailroom(skb), /* buffer size */
sc->sc_rxbufsize,
0);
if (sc->sc_rxlink == NULL)
@ -398,6 +400,13 @@ static struct sk_buff *ath_rxbuf_alloc(struct ath_softc *sc,
* 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->sc_cachelsz - 1);
if (skb != NULL) {
off = ((unsigned long) skb->data) % sc->sc_cachelsz;