Hi,
On 2024-09-17 12:15 +03:00, Felix Fietkau wrote:
> On 17.09.24 08:17, Kalle Valo wrote:
>> Lorenzo Bianconi <lorenzo@xxxxxxxxxx> writes:
>>
>>>> Hi,
>>>>
>>>> I ran into some bug messages while testing linux-next on a MT8186
>>>> Magneton Chromebook (mt8186-corsola-magneton-sku393218). It boots
>>>> to the OS, but at least Wi-Fi and Bluetooth are unavailable.
>>>>
>>>> As a start, I tried reverting commit abbd838c579e ("Merge tag
>>>> 'mt76-for-kvalo-2024-09-06' of https://github.com/nbd168/wireless";)
>>>> and it works fine after that. Didn't have time to do a full bisect,
>>>> but will try if nobody has any immediate opinions.
>>>>
>>>> There are a few traces, here's some select lines to catch your attention,
>>>> not sure how informational they are:
>>>>
>>>> [ 16.040525] kernel BUG at net/core/skbuff.c:2268!
>>>> [ 16.040531] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
>>>> [ 16.040803] CPU: 3 UID: 0 PID: 526 Comm: mt76-sdio-txrx Not tainted
>>>> 6.11.0-next-20240916-deb-00002-g7b544e01c649 #1
>>>> [ 16.040897] Call trace:
>>>> [ 16.040899] pskb_expand_head+0x2b0/0x3c0
>>>> [ 16.040905] mt76s_tx_run_queue+0x274/0x410 [mt76_sdio]
>>>> [ 16.040909] mt76s_txrx_worker+0xe4/0xac8 [mt76_sdio]
>>>> [ 16.040914] mt7921s_txrx_worker+0x98/0x1e0 [mt7921s]
>>>> [ 16.040924] __mt76_worker_fn+0x80/0x128 [mt76]
>>>> [ 16.040934] kthread+0xe8/0xf8
>>>> [ 16.040940] ret_from_fork+0x10/0x20
>>>
>>> Hi,
>>>
>>> I guess this issue has been introduced by the following commit:
>>>
>>> commit 3688c18b65aeb2a1f2fde108400afbab129a8cc1
>>> Author: Felix Fietkau <nbd@xxxxxxxx>
>>> Date: Tue Aug 27 11:30:01 2024 +0200
>>>
>>> wifi: mt76: mt7915: retry mcu messages
>>>
>>> In some cases MCU messages can get lost. Instead of failing completely,
>>> attempt to recover by re-sending them.
>>>
>>> Link: https://patch.msgid.link/20240827093011.18621-14-nbd@xxxxxxxx
>>> Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
>>>
>>>
>>> In particular, skb_get() in mt76_mcu_skb_send_and_get_msg() is bumping skb users
>>> refcount (making the skb shared) and pskb_expand_head() (run by __skb_grow() in
>>> mt76s_tx_run_queue()) does not like shared skbs.
>>>
>>> @Felix: any input on it?
>
> Sorry about that. Please try this patch, it should probably resolve this issue:
>
> ---
> --- a/drivers/net/wireless/mediatek/mt76/mcu.c
> +++ b/drivers/net/wireless/mediatek/mt76/mcu.c
> @@ -84,13 +84,15 @@ 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);
> + 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 +107,7 @@ 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;
>
Tested-by: Alper Nebi Yasak <alpernebiyasak@xxxxxxxxx>
Thanks!
