Re: [Oops] EIP is at ath5k_hw_reset+0x391/0xc82 [ath5k] (2.6.23, latest wireless git)

[Patrick McHardy <kaber@trash.net>]

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Frank de Lange wrote:
> Just got an Atheros-based card from eBay, stuffed it into my Thinkpad
> T23 (ignoring the complaints about two ethernet cards being installed)
> and got myself this Oops:
> 
> BUG: unable to handle kernel NULL pointer dereference at virtual address
> 00000000
>  [...]
> CPU:    0
>    Not tainted VLI
> EFLAGS: 00010246   (2.6.23-t23-01 #3)
> EIP is at ath5k_hw_reset+0x391/0xc82 [ath5k]


I had the same Oops with the internal card of a Thinkpad T42.
The reason is that the rate table lookup for MODE_ATHEROS_TURBOG
returns NULL because the capability bit is not set. I haven't
tracked down the cause yet, but this patch fixes the Oops for me.

On a related issue, the same card can receive packets fine,
but all packets sent are received with the first 16 bytes of
ethernet and IP header missing (the remaining data is fine).
I didn't find the cause for this either, the packet appears
to be fine up to the tx function. Anyone have a hint where to
continue looking? Could this be related to the missing
capability bit and an incorrect rate table being used?

lspci -vvv:

02:02.0 Ethernet controller: Atheros Communications, Inc. AR5212
802.11abg NIC (rev 01)
        Subsystem: AMBIT Microsystem Corp. Unknown device 0408
        Control: I/O- Mem+ BusMaster- SpecCycle- MemWINV+ VGASnoop-
ParErr- Stepping- SERR+ FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
        Interrupt: pin A routed to IRQ 11
        Region 0: Memory at c0210000 (32-bit, non-prefetchable) [size=64K]
        Capabilities: [44] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=2 PME-

iwconfig output:

ath0      IEEE 802.11b  ESSID:"wlan"
          Mode:Managed  Frequency:2.412 GHz  Access Point: Not-Associated
          Tx-Power=27 dBm
          Retry min limit:7   RTS thr:off   Fragment thr=2346 B
          Encryption key:[...]
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

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diff --git a/drivers/net/wireless/ath5k/hw.c b/drivers/net/wireless/ath5k/hw.c
index ae4c5b5..8018af5 100644
--- a/drivers/net/wireless/ath5k/hw.c
+++ b/drivers/net/wireless/ath5k/hw.c
@@ -499,9 +499,10 @@ const struct ath5k_rate_table *ath5k_hw_get_rate_table(struct ath_hw *hal,
 {
 	AR5K_TRACE;
 
+#if 0
 	if (!test_bit(mode, hal->ah_capabilities.cap_mode))
 		return NULL;
-
+#endif
 	/* Get rate tables */
 	switch (mode) {
 	case MODE_IEEE80211A: