When driver fail to reset card ah->curchan value stay NULL. When
later driver try to update tx power it oops by using ah->curchan
(calltrace is shown below).
This problem were reported at various places and for some it was
fixed by making ath9k_hw_chip_reset() do not fail. I have this bug
report on some oldish RHEL kernel with AR9285, however it's hard to
debug where reset fail when kernel OOPS, so I think this patch
should be applied. Hopefully ah->curchan is not used unconditionally
on other places until is initialized on ath9k_config().
ath: phy0: Chip reset failed
ath: phy0: Unable to reset hardware; reset status -22 (freq 2412 MHz)
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<f8a35585>] ath9k_hw_set_txpowerlimit+0x25/0x80 [ath9k_hw]
Oops: 0000 [#1] SMP
<snip>
Call Trace:
[<f8aac1aa>] ? ath9k_cmn_update_txpow+0x1a/0x30 [ath9k_common]
[<f8cf4f4e>] ? ath_complete_reset+0x4e/0x130 [ath9k]
[<f8cf54d7>] ? ath9k_start+0x127/0x1e0 [ath9k]
[<f8c2e52f>] ? ieee80211_do_open+0x30f/0x910 [mac80211]
[<c07bd96d>] ? dev_open+0x8d/0xf0
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
---
drivers/net/wireless/ath/ath9k/common.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/common.c b/drivers/net/wireless/ath/ath9k/common.c
index c67d0e0..099f3d4 100644
--- a/drivers/net/wireless/ath/ath9k/common.c
+++ b/drivers/net/wireless/ath/ath9k/common.c
@@ -369,7 +369,7 @@ void ath9k_cmn_update_txpow(struct ath_hw *ah, u16 cur_txpow,
{
struct ath_regulatory *reg = ath9k_hw_regulatory(ah);
- if (reg->power_limit != new_txpow)
+ if (ah->curchan && reg->power_limit != new_txpow)
ath9k_hw_set_txpowerlimit(ah, new_txpow, false);
/* read back in case value is clamped */
--
1.7.1
