On 10/14/2010 02:52 PM, Björn Smedman wrote:
2010/10/13 Björn Smedman<bjorn.smedman@xxxxxxxxxxx>:
Hi Ben,
First of all keep up the good work. :)
On Wed, Oct 13, 2010 at 6:39 PM, Ben Greear<greearb@xxxxxxxxxxxxxxx> wrote:
[snip]
Either way, it seems safer to null out the bf_ampdu field after
the memory is consumed..it could prevent some tricky bugs later.
I think this is a good idea. But it probably wont be enough to null
out bf_mpdu. You also need to look at bf_buf_addr (which if I
understand correctly is the physical address the DMA engine will
actually write RXed frames to) and bf_dmacontext (which seems in most
cases to hold an identical address and may in fact be where the DMA
engine will really write the frame).
I took another look at the code. It turns out both bf_buf_addr and
bf_dmacontext are in fact meaningless to the DMA. Instead each bf
holds a pointer (bf_desc) to the real DMA descriptor which in turn
holds the address (ds_data) where the DMA will really (really this
time) write the frame. There is also a field to hold the virtual
address of the same place (ds_vdata).
It's a little too much work for me to set up the testbed you have Ben
but would be interesting to see what happens if you set
bf->bf_desc->ds_{data,vdata} = 0 as well. No?
I tried the patch below, and it didn't seem to help. Might even
have hurt..as it died on divide-by-zero error:
Call Trace:
[<c075e490>] ? printk+0xf/0x17
[<c075e37e>] panic+0x50/0x153
[<c07619db>] oops_end+0x92/0xa1
[<c04051cc>] die+0x53/0x59
[<c07612a3>] do_trap+0x89/0xa2
[<c0403b12>] ? do_divide_error+0x0/0x78
[<c0403b80>] do_divide_error+0x6e/0x78
[<faef811e>] ? ath9k_hw_ani_monitor+0x37/0x40e [ath9k_hw]
[<fb1f77d9>] ? ath9k_ioread32+0x25/0x5b [ath9k]
[<c045553a>] ? trace_hardirqs_off+0xb/0xd
[<c0581210>] ? trace_hardirqs_off_thunk+0xc/0x10
[<c076103f>] error_code+0x5f/0x70
[<c0403b12>] ? do_divide_error+0x0/0x78
[<faef811e>] ? ath9k_hw_ani_monitor+0x37/0x40e [ath9k_hw]
[<fb1fa783>] ath_ani_calibrate+0x143/0x20b [ath9k]
[<c043d58f>] run_timer_softirq+0x14f/0x1e7
That might be an existing bug, however...
Thanks,
Ben
diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 0c917e5..8fba13d 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -737,4 +737,6 @@ bool ath_mac80211_start_queue(struct ath_softc *sc, u16 skb_queue);
void ath_start_rfkill_poll(struct ath_softc *sc);
extern void ath9k_rfkill_poll_state(struct ieee80211_hw *hw);
+void ath_clear_dma_ptrs(struct ath_buf *bf);
+
#endif /* ATH9K_H */
diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index 97d471f..cc406f9 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -139,7 +139,7 @@ static struct ath_buf *ath_beacon_generate(struct ieee80211_hw *hw,
dma_unmap_single(sc->dev, bf->bf_buf_addr,
skb->len, DMA_TO_DEVICE);
dev_kfree_skb_any(skb);
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
}
/* Get a new beacon from mac80211 */
@@ -167,8 +167,7 @@ static struct ath_buf *ath_beacon_generate(struct ieee80211_hw *hw,
skb->len, DMA_TO_DEVICE);
if (unlikely(dma_mapping_error(sc->dev, bf->bf_buf_addr))) {
dev_kfree_skb_any(skb);
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
ath_print(common, ATH_DBG_FATAL,
"dma_mapping_error on beaconing\n");
return NULL;
@@ -256,8 +255,7 @@ int ath_beacon_alloc(struct ath_wiphy *aphy, struct ieee80211_vif *vif)
dma_unmap_single(sc->dev, bf->bf_buf_addr,
skb->len, DMA_TO_DEVICE);
dev_kfree_skb_any(skb);
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
}
/* NB: the beacon data buffer must be 32-bit aligned. */
@@ -302,8 +300,7 @@ int ath_beacon_alloc(struct ath_wiphy *aphy, struct ieee80211_vif *vif)
skb->len, DMA_TO_DEVICE);
if (unlikely(dma_mapping_error(sc->dev, bf->bf_buf_addr))) {
dev_kfree_skb_any(skb);
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
ath_print(common, ATH_DBG_FATAL,
"dma_mapping_error on beacon alloc\n");
return -ENOMEM;
@@ -329,8 +326,7 @@ void ath_beacon_return(struct ath_softc *sc, struct ath_vif *avp)
dma_unmap_single(sc->dev, bf->bf_buf_addr,
skb->len, DMA_TO_DEVICE);
dev_kfree_skb_any(skb);
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
}
list_add_tail(&bf->list, &sc->beacon.bbuf);
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index bcd3892..1722a21 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -213,6 +213,17 @@ static void ath_update_survey_stats(struct ath_softc *sc)
ath_update_survey_nf(sc, pos);
}
+void ath_clear_dma_ptrs(struct ath_buf *bf)
+{
+ struct ath_desc *ds = bf->bf_desc;
+ bf->bf_buf_addr = 0;
+ bf->bf_mpdu = NULL;
+ if (ds) {
+ ds->ds_data = 0;
+ ds->ds_vdata = NULL;
+ }
+}
+
/*
* Set/change channels. If the channel is really being changed, it's done
* by reseting the chip. To accomplish this we must first cleanup any pending
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index fd778d2..5afb46f 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -269,8 +269,7 @@ static int ath_rx_edma_init(struct ath_softc *sc, int nbufs)
if (unlikely(dma_mapping_error(sc->dev,
bf->bf_buf_addr))) {
dev_kfree_skb_any(skb);
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
ath_print(common, ATH_DBG_FATAL,
"dma_mapping_error() on RX init\n");
error = -ENOMEM;
@@ -360,8 +359,7 @@ int ath_rx_init(struct ath_softc *sc, int nbufs)
if (unlikely(dma_mapping_error(sc->dev,
bf->bf_buf_addr))) {
dev_kfree_skb_any(skb);
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
ath_print(common, ATH_DBG_FATAL,
"dma_mapping_error() on RX init\n");
error = -ENOMEM;
@@ -396,8 +394,7 @@ void ath_rx_cleanup(struct ath_softc *sc)
common->rx_bufsize,
DMA_FROM_DEVICE);
dev_kfree_skb(skb);
- bf->bf_buf_addr = 0;
- bf->bf_mpdu = NULL;
+ ath_clear_dma_ptrs(bf);
}
}
@@ -1741,8 +1738,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
if (unlikely(dma_mapping_error(sc->dev,
bf->bf_buf_addr))) {
dev_kfree_skb_any(requeue_skb);
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
ath_print(common, ATH_DBG_FATAL,
"dma_mapping_error() on RX\n");
ath_rx_send_to_mac80211(hw, sc, skb, rxs);
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index a5e5f27..e86f59c 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1644,8 +1644,7 @@ static int ath_tx_setup_buffer(struct ieee80211_hw *hw, struct ath_buf *bf,
bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
skb->len, DMA_TO_DEVICE);
if (unlikely(dma_mapping_error(sc->dev, bf->bf_buf_addr))) {
- bf->bf_mpdu = NULL;
- bf->bf_buf_addr = 0;
+ ath_clear_dma_ptrs(bf);
ath_print(ath9k_hw_common(sc->sc_ah), ATH_DBG_FATAL,
"dma_mapping_error() on TX\n");
return -ENOMEM;
@@ -1915,7 +1914,6 @@ static void ath_tx_complete_buf(struct ath_softc *sc, struct ath_buf *bf,
}
dma_unmap_single(sc->dev, bf->bf_buf_addr, skb->len, DMA_TO_DEVICE);
- bf->bf_buf_addr = 0;
if (bf->bf_state.bfs_paprd) {
if (time_after(jiffies,
@@ -1931,7 +1929,7 @@ static void ath_tx_complete_buf(struct ath_softc *sc, struct ath_buf *bf,
/* At this point, skb (bf->bf_mpdu) is consumed...make sure we don't
* accidentally reference it later.
*/
- bf->bf_mpdu = NULL;
+ ath_clear_dma_ptrs(bf);
/*
* Return the list of ath_buf of this mpdu to free queue
/Björn
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--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
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