[PATCH] wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()

[PATCH] wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()

[Toke Høiland-Jørgensen]

This partially reverts commit e161d4b60ae3a5356e07202e0bfedb5fad82c6aa.

Turns out the channelmap variable is not actually read-only, it's modified
through the MCI_GPM_CLR_CHANNEL_BIT() macro further down in the function,
so making it read-only causes page faults when that code is hit.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217183
Fixes: e161d4b60ae3 ("wifi: ath9k: Make arrays prof_prio and channelmap static const")
Cc: stable@vger.kernel.org
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
---
 drivers/net/wireless/ath/ath9k/mci.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/mci.c b/drivers/net/wireless/ath/ath9k/mci.c
index 3363fc4e8966..a0845002d6fe 100644
--- a/drivers/net/wireless/ath/ath9k/mci.c
+++ b/drivers/net/wireless/ath/ath9k/mci.c
@@ -646,9 +646,7 @@ void ath9k_mci_update_wlan_channels(struct ath_softc *sc, bool allow_all)
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath9k_hw_mci *mci = &ah->btcoex_hw.mci;
 	struct ath9k_channel *chan = ah->curchan;
-	static const u32 channelmap[] = {
-		0x00000000, 0xffff0000, 0xffffffff, 0x7fffffff
-	};
+	u32 channelmap[] = {0x00000000, 0xffff0000, 0xffffffff, 0x7fffffff};
 	int i;
 	s16 chan_start, chan_end;
 	u16 wlan_chan;
-- 
2.40.0

Re: [PATCH] wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()

[Kalle Valo]

Toke Høiland-Jørgensen <toke@toke.dk> writes:

> This partially reverts commit e161d4b60ae3a5356e07202e0bfedb5fad82c6aa.
>
> Turns out the channelmap variable is not actually read-only, it's modified
> through the MCI_GPM_CLR_CHANNEL_BIT() macro further down in the function,
> so making it read-only causes page faults when that code is hit.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217183
> Fixes: e161d4b60ae3 ("wifi: ath9k: Make arrays prof_prio and channelmap static const")
> Cc: stable@vger.kernel.org
> Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

I guess the casting in MCI_GPM_CLR_CHANNEL_BIT() hide this and made it
impossible for the compiler to detect it? A perfect example why I hate
casting :)

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH] wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()

[Toke Høiland-Jørgensen]

Kalle Valo <kvalo@kernel.org> writes:

> Toke Høiland-Jørgensen <toke@toke.dk> writes:
>
>> This partially reverts commit e161d4b60ae3a5356e07202e0bfedb5fad82c6aa.
>>
>> Turns out the channelmap variable is not actually read-only, it's modified
>> through the MCI_GPM_CLR_CHANNEL_BIT() macro further down in the function,
>> so making it read-only causes page faults when that code is hit.
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217183
>> Fixes: e161d4b60ae3 ("wifi: ath9k: Make arrays prof_prio and channelmap static const")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
>
> I guess the casting in MCI_GPM_CLR_CHANNEL_BIT() hide this and made it
> impossible for the compiler to detect it? A perfect example why I hate
> casting :)

Yup, exactly. I was also assuming the compiler would catch it, but yay, C! :/

Anyway, cf the bugzilla this was a pretty bad regression for 6.2, so
would be good to move this along reasonably quickly (although I guess we
just missed the -net PR for rc7)...

-Toke

Re: [PATCH] wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()

[Kalle Valo]

Toke Høiland-Jørgensen <toke@toke.dk> wrote:

> This partially reverts commit e161d4b60ae3a5356e07202e0bfedb5fad82c6aa.
> 
> Turns out the channelmap variable is not actually read-only, it's modified
> through the MCI_GPM_CLR_CHANNEL_BIT() macro further down in the function,
> so making it read-only causes page faults when that code is hit.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217183
> Fixes: e161d4b60ae3 ("wifi: ath9k: Make arrays prof_prio and channelmap static const")
> Cc: stable@vger.kernel.org
> Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>

Patch applied to ath-next branch of ath.git, thanks.

b956e3110a79 wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20230413214118.153781-1-toke@toke.dk/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH] wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()

[Colin King (gmail)]

On 19/04/2023 15:24, Kalle Valo wrote:
> Toke Høiland-Jørgensen <toke@toke.dk> wrote:
> 
>> This partially reverts commit e161d4b60ae3a5356e07202e0bfedb5fad82c6aa.
>>
>> Turns out the channelmap variable is not actually read-only, it's modified
>> through the MCI_GPM_CLR_CHANNEL_BIT() macro further down in the function,
>> so making it read-only causes page faults when that code is hit.
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217183
>> Fixes: e161d4b60ae3 ("wifi: ath9k: Make arrays prof_prio and channelmap static const")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
>> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
> 
> Patch applied to ath-next branch of ath.git, thanks.
> 
> b956e3110a79 wifi: ath9k: Don't mark channelmap stack variable read-only in ath9k_mci_update_wlan_channels()
> 

Thanks. Apologies for the regression. My bad.