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ath9k: Handle -ENOMEM on RX gracefully 

We would get an oops on RX on -ENOMEM by passing
NULL to the hardware on ath_rx_buf_link(). The oops
would look something like this:

ath_rx_tasklet+0x515/0x53b
ath9k_tasklet+0x48
tasklet_action
__do_softirq
irq_exit
do_IRQ

RIP: ath_rx_buf_link+0x3a

We correct this by handling the requeue directly on
the ath_rx_tasklet() and trying to allocate an skb
*prior* to sending up the last hardware processed
skb. If we run out of memory this gauranteees we have
skbs to work with while it simply drops new received
frames.

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 2008-11-21 17:41:33 -08:00 committed by John W. Linville
parent 24689c8590
commit cb71d9bafb
1 changed files with 26 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
drivers/net/wireless/ath9k/recv.c
View File

@ -81,29 +81,6 @@ static struct sk_buff *ath_rxbuf_alloc(struct ath_softc *sc, u32 len)
return skb;
}
static void ath_rx_requeue(struct ath_softc *sc, struct ath_buf *bf)
{
struct sk_buff *skb;
ASSERT(bf != NULL);
if (bf->bf_mpdu == NULL) {
skb = ath_rxbuf_alloc(sc, sc->sc_rxbufsize);
if (skb != NULL) {
bf->bf_mpdu = skb;
bf->bf_buf_addr = pci_map_single(sc->pdev, skb->data,
skb_end_pointer(skb) - skb->head,
PCI_DMA_FROMDEVICE);
bf->bf_dmacontext = bf->bf_buf_addr;
}
}
list_move_tail(&bf->list, &sc->sc_rxbuf);
ath_rx_buf_link(sc, bf);
}
static int ath_rate2idx(struct ath_softc *sc, int rate)
{
int i = 0, cur_band, n_rates;
@ -445,7 +422,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
struct ath_buf *bf;
struct ath_desc *ds;
struct sk_buff *skb = NULL;
struct sk_buff *skb = NULL, *requeue_skb;
struct ieee80211_rx_status rx_status;
struct ath_hal *ah = sc->sc_ah;
struct ieee80211_hdr *hdr;
@ -522,17 +499,28 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
* chain it back at the queue without processing it.
*/
if (flush)
goto rx_next;
goto requeue;
if (!ds->ds_rxstat.rs_datalen)
goto rx_next;
goto requeue;
/* The status portion of the descriptor could get corrupted. */
if (sc->sc_rxbufsize < ds->ds_rxstat.rs_datalen)
goto rx_next;
goto requeue;
if (!ath_rx_prepare(skb, ds, &rx_status, &decrypt_error, sc))
goto rx_next;
goto requeue;
/* 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->sc_rxbufsize);
/* If there is no memory we ignore the current RX'd frame,
* tell hardware it can give us a new frame using the old
* skb and put it at the tail of the sc->sc_rxbuf list for
* processing. */
if (!requeue_skb)
goto requeue;
/* Sync and unmap the frame */
pci_dma_sync_single_for_cpu(sc->pdev, bf->bf_buf_addr,
@ -569,7 +557,13 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
/* Send the frame to mac80211 */
__ieee80211_rx(sc->hw, skb, &rx_status);
bf->bf_mpdu = NULL;
/* We will now give hardware our shiny new allocated skb */
bf->bf_mpdu = requeue_skb;
bf->bf_buf_addr = pci_map_single(sc->pdev, requeue_skb->data,
sc->sc_rxbufsize,
PCI_DMA_FROMDEVICE);
bf->bf_dmacontext = bf->bf_buf_addr;
/*
* change the default rx antenna if rx diversity chooses the
@ -581,8 +575,9 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
} else {
sc->sc_rxotherant = 0;
}
rx_next:
ath_rx_requeue(sc, bf);
requeue:
list_move_tail(&bf->list, &sc->sc_rxbuf);
ath_rx_buf_link(sc, bf);
} while (1);
spin_unlock_bh(&sc->sc_rxbuflock);