On 11/20/19 1:03 PM, Felix Fietkau wrote:
> On 2019-11-20 12:59, Markus Theil wrote:
>> On 11/20/19 12:46 PM, Felix Fietkau wrote:
>>> Fixes potential RCU issues and avoids calling ieee80211_rx_napi with softirq
>>> enabled.
>>>
>>> Reported-by: Markus Theil <markus.theil@xxxxxxxxxxxxx>
>>> Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
>>> ---
>>> drivers/net/wireless/mediatek/mt76/dma.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
>>> index 6173c80189ba..ed0ee2d4a452 100644
>>> --- a/drivers/net/wireless/mediatek/mt76/dma.c
>>> +++ b/drivers/net/wireless/mediatek/mt76/dma.c
>>> @@ -528,7 +528,7 @@ mt76_dma_rx_poll(struct napi_struct *napi, int budget)
>>> dev = container_of(napi->dev, struct mt76_dev, napi_dev);
>>> qid = napi - dev->napi;
>>>
>>> - rcu_read_lock();
>>> + rcu_read_lock_bh();
>>>
>>> do {
>>> cur = mt76_dma_rx_process(dev, &dev->q_rx[qid], budget - done);
>>> @@ -536,7 +536,7 @@ mt76_dma_rx_poll(struct napi_struct *napi, int budget)
>>> done += cur;
>>> } while (cur && done < budget);
>>>
>>> - rcu_read_unlock();
>>> + rcu_read_unlock_bh();
>>>
>>> if (done < budget && napi_complete(napi))
>>> dev->drv->rx_poll_complete(dev, qid);
>> This patch is incomplete. The same problem exists for usb. I'll send a fix for that.
> How so? On usb, it is called from a tasklet already.
>
> - Felix
I've noticed the bug I reported on USB devices. I've only seen that mt76_rx_aggr_reorder_work also accesses mt76_rx_complete.
Maybe it only worked for me by accident. Of course, the tasklet should not run in parallel with multiple instances.
Markus
