diff mbox

ath10k: fix bug in masking of TID value

Message ID 20180615120153.4677-1-erik.stromdahl@gmail.com (mailing list archive)
State Accepted
Commit d1a566bec5887988cd7e4b7cf98b05e1ff7a0f8a
Delegated to: Kalle Valo
Headers show

Commit Message

Erik Stromdahl June 15, 2018, 12:01 p.m. UTC
Although the TID mask is 0xf, the modulus operation does still not
produce identical results as the bitwise and operator.

If the TID is 15, the modulus operation will "convert" it to 0, whereas
the bitwise and will keep it as 15.

Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
---
 drivers/net/wireless/ath/ath10k/htt_tx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Kalle Valo June 15, 2018, 12:58 p.m. UTC | #1
Erik Stromdahl <erik.stromdahl@gmail.com> writes:

> Although the TID mask is 0xf, the modulus operation does still not
> produce identical results as the bitwise and operator.
>
> If the TID is 15, the modulus operation will "convert" it to 0, whereas
> the bitwise and will keep it as 15.
>
> Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
> ---
>  drivers/net/wireless/ath/ath10k/htt_tx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
> index 89157c5b5e5f..be5b52aaffa6 100644
> --- a/drivers/net/wireless/ath/ath10k/htt_tx.c
> +++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
> @@ -1056,7 +1056,7 @@ static u8 ath10k_htt_tx_get_tid(struct sk_buff *skb, bool is_eth)
>  	if (!is_eth && ieee80211_is_mgmt(hdr->frame_control))
>  		return HTT_DATA_TX_EXT_TID_MGMT;
>  	else if (cb->flags & ATH10K_SKB_F_QOS)
> -		return skb->priority % IEEE80211_QOS_CTL_TID_MASK;
> +		return skb->priority & IEEE80211_QOS_CTL_TID_MASK;

I guess you just found this during code review? If yes, I'll add that to
the commit log.
Erik Stromdahl June 15, 2018, 7:38 p.m. UTC | #2
Hi Kalle,

On 06/15/2018 02:58 PM, Kalle Valo wrote:
> Erik Stromdahl <erik.stromdahl@gmail.com> writes:
> 
>> Although the TID mask is 0xf, the modulus operation does still not
>> produce identical results as the bitwise and operator.
>>
>> If the TID is 15, the modulus operation will "convert" it to 0, whereas
>> the bitwise and will keep it as 15.
>>
>> Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
>> ---
>>   drivers/net/wireless/ath/ath10k/htt_tx.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
>> index 89157c5b5e5f..be5b52aaffa6 100644
>> --- a/drivers/net/wireless/ath/ath10k/htt_tx.c
>> +++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
>> @@ -1056,7 +1056,7 @@ static u8 ath10k_htt_tx_get_tid(struct sk_buff *skb, bool is_eth)
>>   	if (!is_eth && ieee80211_is_mgmt(hdr->frame_control))
>>   		return HTT_DATA_TX_EXT_TID_MGMT;
>>   	else if (cb->flags & ATH10K_SKB_F_QOS)
>> -		return skb->priority % IEEE80211_QOS_CTL_TID_MASK;
>> +		return skb->priority & IEEE80211_QOS_CTL_TID_MASK;
> 
> I guess you just found this during code review? If yes, I'll add that to
> the commit log.
> 
Correct, I kind of stumbled upon it while working with TX bundling for SDIO.

--
Erik
Kalle Valo June 28, 2018, 9:55 a.m. UTC | #3
Erik Stromdahl <erik.stromdahl@gmail.com> wrote:

> Although the TID mask is 0xf, the modulus operation does still not
> produce identical results as the bitwise and operator. If the TID is 15, the
> modulus operation will "convert" it to 0, whereas the bitwise and will keep it
> as 15.
> 
> This was found during code review.
> 
> Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

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

d1a566bec588 ath10k: fix bug in masking of TID value
diff mbox

Patch

diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
index 89157c5b5e5f..be5b52aaffa6 100644
--- a/drivers/net/wireless/ath/ath10k/htt_tx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
@@ -1056,7 +1056,7 @@  static u8 ath10k_htt_tx_get_tid(struct sk_buff *skb, bool is_eth)
 	if (!is_eth && ieee80211_is_mgmt(hdr->frame_control))
 		return HTT_DATA_TX_EXT_TID_MGMT;
 	else if (cb->flags & ATH10K_SKB_F_QOS)
-		return skb->priority % IEEE80211_QOS_CTL_TID_MASK;
+		return skb->priority & IEEE80211_QOS_CTL_TID_MASK;
 	else
 		return HTT_DATA_TX_EXT_TID_NON_QOS_MCAST_BCAST;
 }