[PATCH 1/2] ath9k: Fix kernel panic caused by invalid rate index access.

[PATCH 1/2] ath9k: Fix kernel panic caused by invalid rate index access.

[Senthil Balasubramanian]

With the recent tx status optimization in mac80211, we bail out as
and and when invalid rate index is found. So the behavior of resetting
rate idx to -1 and count to 0 has changed for the rate indexes that
were not part of the driver's retry series.

This has resulted in ath9k using incorrect rate table index which
caused the system to panic. Ideally ath9k need to loop only for the
indexes that were part of the retry series and so simply use hw->max_rates
as the loop counter.

Pasted the stack trace of the panic issue for reference.

[  754.093192] BUG: unable to handle kernel paging request at ffff88046a9025b0
[  754.093256] IP: [<ffffffffa02eac49>] ath_tx_status+0x209/0x2f0 [ath9k]
[  754.094888] Call Trace:
[  754.094903]  <IRQ>
[  754.094928]  [<ffffffffa051f883>] ieee80211_tx_status+0x203/0x9e0 [mac80211]
[  754.094975]  [<ffffffffa053e305>] ? __ieee80211_wake_queue+0x125/0x140 [mac80211]
[  754.095017]  [<ffffffffa02e66c9>] ath_tx_complete_buf+0x1b9/0x370 [ath9k]
[  754.095054]  [<ffffffffa02e6fcf>] ath_tx_complete_aggr+0x51f/0xb50 [ath9k]
[  754.095098]  [<ffffffffa05382a3>] ? ieee80211_prepare_and_rx_handle+0x173/0xab0 [mac80211]
[  754.095148]  [<ffffffff81350e62>] ? _raw_spin_unlock_irqrestore+0x32/0x40
[  754.095186]  [<ffffffffa02e9735>] ath_tx_tasklet+0x365/0x4b0 [ath9k]
[  754.095224]  [<ffffffff8107a2a2>] ? clockevents_program_event+0x62/0xa0
[  754.095261]  [<ffffffffa02e2628>] ath9k_tasklet+0x168/0x1c0 [ath9k]
[  754.095298]  [<ffffffff8105599b>] tasklet_action+0x6b/0xe0
[  754.095331]  [<ffffffff81056278>] __do_softirq+0x98/0x120
[  754.095361]  [<ffffffff8100cd5c>] call_softirq+0x1c/0x30
[  754.095393]  [<ffffffff8100efb5>] do_softirq+0x65/0xa0
[  754.095423]  [<ffffffff810563fd>] irq_exit+0x8d/0x90
[  754.095453]  [<ffffffff8100ebc1>] do_IRQ+0x61/0xe0
[  754.095482]  [<ffffffff81351413>] ret_from_intr+0x0/0x15
[  754.095513]  <EOI>
[  754.095531]  [<ffffffff81014375>] ? native_sched_clock+0x15/0x70
[  754.096475]  [<ffffffffa02bcfa6>] ? acpi_idle_enter_bm+0x24d/0x285 [processor]
[  754.096475]  [<ffffffffa02bcf9f>] ? acpi_idle_enter_bm+0x246/0x285 [processor]
[  754.096475]  [<ffffffff8127fab2>] cpuidle_idle_call+0x82/0x100
[  754.096475]  [<ffffffff8100a236>] cpu_idle+0xa6/0xf0
[  754.096475]  [<ffffffff81339bc1>] rest_init+0x91/0xa0
[  754.096475]  [<ffffffff814efccd>] start_kernel+0x3fd/0x408
[  754.096475]  [<ffffffff814ef347>] x86_64_start_reservations+0x132/0x136
[  754.096475]  [<ffffffff814ef451>] x86_64_start_kernel+0x106/0x115
[  754.096475] RIP  [<ffffffffa02eac49>] ath_tx_status+0x209/0x2f0 [ath9k]

Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
---
 drivers/net/wireless/ath/ath9k/rc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/rc.c b/drivers/net/wireless/ath/ath9k/rc.c
index 960d717..a3241cd 100644
--- a/drivers/net/wireless/ath/ath9k/rc.c
+++ b/drivers/net/wireless/ath/ath9k/rc.c
@@ -1328,7 +1328,7 @@ static void ath_tx_status(void *priv, struct ieee80211_supported_band *sband,
 
 	hdr = (struct ieee80211_hdr *)skb->data;
 	fc = hdr->frame_control;
-	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
+	for (i = 0; i < sc->hw->max_rates; i++) {
 		struct ieee80211_tx_rate *rate = &tx_info->status.rates[i];
 		if (!rate->count)
 			break;
-- 
1.7.3.4

[PATCH 2/2] ath9k: Fix TX queue stuck issue.

[Senthil Balasubramanian]

commit 86271e460a66003dc1f4cbfd845adafb790b7587 introduced a
regression that caused mac80211 queues in stopped state.

ath_drain_all_txq is called in driver flush which would reset
the stopped flag and the mac80211 queues were never started
after that. iperf traffic is completely stalled due to this issue.

Restart the mac80211 queues in driver flush only if the txqs were
drained.

Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
---
 drivers/net/wireless/ath/ath9k/main.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 115f162..5248257 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -2160,6 +2160,8 @@ static void ath9k_flush(struct ieee80211_hw *hw, bool drop)
 	if (!ath_drain_all_txq(sc, false))
 		ath_reset(sc, false);
 
+	ieee80211_wake_queues(hw);
+
 out:
 	ieee80211_queue_delayed_work(hw, &sc->tx_complete_work, 0);
 	mutex_unlock(&sc->mutex);
-- 
1.7.3.4

Re: [PATCH 1/2] ath9k: Fix kernel panic caused by invalid rate index access.

[Helmut Schaa]

Hi,

Am Mittwoch, 23. März 2011 schrieb Senthil Balasubramanian:
> With the recent tx status optimization in mac80211, we bail out as
> and and when invalid rate index is found. So the behavior of resetting
> rate idx to -1 and count to 0 has changed for the rate indexes that
> were not part of the driver's retry series.
> 
> This has resulted in ath9k using incorrect rate table index which
> caused the system to panic. Ideally ath9k need to loop only for the
> indexes that were part of the retry series and so simply use hw->max_rates
> as the loop counter.

Sorry for the trouble. I didn't consider rc algorithms
outside of net/mac80211/ ...

> ---
>  drivers/net/wireless/ath/ath9k/rc.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath9k/rc.c b/drivers/net/wireless/ath/ath9k/rc.c
> index 960d717..a3241cd 100644
> --- a/drivers/net/wireless/ath/ath9k/rc.c
> +++ b/drivers/net/wireless/ath/ath9k/rc.c
> @@ -1328,7 +1328,7 @@ static void ath_tx_status(void *priv, struct ieee80211_supported_band *sband,
>  
>  	hdr = (struct ieee80211_hdr *)skb->data;
>  	fc = hdr->frame_control;
> -	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
> +	for (i = 0; i < sc->hw->max_rates; i++) {
>  		struct ieee80211_tx_rate *rate = &tx_info->status.rates[i];
>  		if (!rate->count)
>  			break;

You could also just change that check to

	if (rate->idx < 0)
		break;

instead as mac80211 already assumes the tx status rates array is terminated
by the driver by setting the idx to -1.

Helmut