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Commit cb71d9ba authored by Luis R. Rodriguez's avatar Luis R. Rodriguez Committed by John W. Linville
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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: default avatarLuis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 24689c85

drivers/net/wireless/ath9k/recv.c

+26 −31
Original line number Diff line number Diff line
@@ -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);