Re: [PATCH] wifi: mt76: do not increase mcu skb refcount if retry is not supported

[Kalle Valo <kvalo@kernel.org>]

Muhammad Usama Anjum <Usama.Anjum@collabora.com> writes:

> On 9/17/24 4:09 PM, Felix Fietkau wrote:
>
>> If mcu_skb_prepare_msg is not implemented, incrementing skb refcount does not
>> work for mcu message retry. In some cases (e.g. on SDIO), shared skbs can trigger
>> a BUG_ON, crashing the system.
>> Fix this by only incrementing refcount if retry is actually supported.
>> 
>> Fixes: 3688c18b65ae ("wifi: mt76: mt7915: retry mcu messages")
>> Reported-by: Nícolas F. R. A. Prado <nfraprado@collabora.com> #KernelCI
>> Tested-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>> ---
>>  drivers/net/wireless/mediatek/mt76/mcu.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/net/wireless/mediatek/mt76/mcu.c b/drivers/net/wireless/mediatek/mt76/mcu.c
>> index 98da82b74094..3353012e8542 100644
>> --- a/drivers/net/wireless/mediatek/mt76/mcu.c
>> +++ b/drivers/net/wireless/mediatek/mt76/mcu.c
>> @@ -84,13 +84,16 @@ int mt76_mcu_skb_send_and_get_msg(struct mt76_dev *dev, struct sk_buff *skb,
>>  	mutex_lock(&dev->mcu.mutex);
>>  
>>  	if (dev->mcu_ops->mcu_skb_prepare_msg) {
>> +		orig_skb = skb;
>>  		ret = dev->mcu_ops->mcu_skb_prepare_msg(dev, skb, cmd, &seq);
>>  		if (ret < 0)
>>  			goto out;
>>  	}
>>  
>>  retry:
>> -	orig_skb = skb_get(skb);
>> +	/* orig skb might be needed for retry, mcu_skb_send_msg consumes it */
>> +	if (orig_skb)
>> +		skb_get(orig_skb);
>>  	ret = dev->mcu_ops->mcu_skb_send_msg(dev, skb, cmd, &seq);
>>  	if (ret < 0)
>>  		goto out;
>> @@ -105,7 +108,7 @@ int mt76_mcu_skb_send_and_get_msg(struct mt76_dev *dev, struct sk_buff *skb,
>>  	do {
>>  		skb = mt76_mcu_get_response(dev, expires);
>>  		if (!skb && !test_bit(MT76_MCU_RESET, &dev->phy.state) &&
>> -		    retry++ < dev->mcu_ops->max_retry) {
>> +		    orig_skb && retry++ < dev->mcu_ops->max_retry) {
>>  			dev_err(dev->dev, "Retry message %08x (seq %d)\n",
>>  				cmd, seq);
>>  			skb = orig_skb;
> This patch is in next from 5 weeks. As 3688c18b65ae ("wifi: mt76: mt7915: retry mcu messages") is
> already in the mainline, why this fix hasn't been included in mainline? I thought fixes are included
> as soon as possible in mainline RCs. Am I missing something? 
>
> Are we planning to include this fix in next release instead of current one?

The commit is now in wireless tree:

34b695481084 wifi: mt76: do not increase mcu skb refcount if retry is not supported

With good luck it will be in v6.12-rc5 but no guarantees.

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