On Thu, 6 Jun 2019 23:02:08 +0200, Lorenzo Bianconi wrote: > > On Thu, 6 Jun 2019 14:26:12 +0200, Lorenzo Bianconi wrote: > Hi Jakub, > > thx for the fast review :) I guess I'm used to the 24h "review timeout" on netdev :) > > Is this a new thing? I def tested unplugging the dongle under > > traffic, but that must had been in 3.19 days :S > > I do not know if the issue has been introduced in recent kernel, I am > able to trigger it in a vm running > wireless-drivers-next and it has been reported here: > https://bugzilla.kernel.org/show_bug.cgi?id=203249 I see. I'm just worried that we make a mistake here and it will get backported all the way back to very old kernels because of the fixes tag. If old kernels worked perhaps it's not worth disturbing them. > > > Fixes: c869f77d6abb ("add mt7601u driver") > > > Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx> > > > --- > > > I will post a patch to fix tx side as well > > > --- > > > drivers/net/wireless/mediatek/mt7601u/dma.c | 33 ++++++++++----------- > > > 1 file changed, 16 insertions(+), 17 deletions(-) > > > > > > diff --git a/drivers/net/wireless/mediatek/mt7601u/dma.c b/drivers/net/wireless/mediatek/mt7601u/dma.c > > > index f7edeffb2b19..e7703990b291 100644 > > > --- a/drivers/net/wireless/mediatek/mt7601u/dma.c > > > +++ b/drivers/net/wireless/mediatek/mt7601u/dma.c > > > @@ -193,10 +193,20 @@ static void mt7601u_complete_rx(struct urb *urb) > > > struct mt7601u_rx_queue *q = &dev->rx_q; > > > unsigned long flags; > > > > > > - spin_lock_irqsave(&dev->rx_lock, flags); > > > + switch (urb->status) { > > > + case -ECONNRESET: > > > + case -ESHUTDOWN: > > > + case -ENOENT: > > > + return; > > > > So we assume this is non-recoverable? Everything will fail after? > > Because pending is incremented linearly :S That's why there is a > > warning here. > > AFAIK -ECONNRESET/-ENOENT are related to urb unlink/kill while > -ESHUTDOWN is related to device disconnection. > I guess we can assume the device has been removed if we get these errors Makes sense. A bit of an implicit assumption, USB subsystem may break this for us. Let's at least put a comment here so we can go back and know that at the time of committing we did double check? > > > + default: > > > + dev_err_ratelimited(dev->dev, "rx urb failed: %d\n", > > > + urb->status); > > > + /* fall through */ > > > + case 0: > > > + break; > > > + } > > > > > > - if (mt7601u_urb_has_error(urb)) > > > - dev_err(dev->dev, "Error: RX urb failed:%d\n", urb->status); > > > + spin_lock_irqsave(&dev->rx_lock, flags); > > > if (WARN_ONCE(q->e[q->end].urb != urb, "RX urb mismatch")) > > > goto out; > > > > > > @@ -363,19 +373,10 @@ int mt7601u_dma_enqueue_tx(struct mt7601u_dev *dev, struct sk_buff *skb, > > > static void mt7601u_kill_rx(struct mt7601u_dev *dev) > > > { > > > int i; > > > - unsigned long flags; > > > - > > > - spin_lock_irqsave(&dev->rx_lock, flags); > > > > > > - for (i = 0; i < dev->rx_q.entries; i++) { > > > - int next = dev->rx_q.end; > > > - > > > - spin_unlock_irqrestore(&dev->rx_lock, flags); > > > - usb_poison_urb(dev->rx_q.e[next].urb); > > > - spin_lock_irqsave(&dev->rx_lock, flags); > > > - } > > > > Why is there no need to take the lock? Admittedly it's not clear what > > this lock is protecting here :P Perhaps a separate patch to remove the > > unnecessary locking with an explanation? > > usb_poison_urb() can run concurrently with urb completion so I guess > we do not need locks here. > I guess we need to maintain this chunk in the same patch since now > when the device is disconnected > we do not increment dev->rx_q.end. What do you think? Ah, I see! The completion used to run in between the unlock/lock! Now we just poison out of order, because completion doesn't care about ordering for errored URBs. Perhaps worth putting in the commit message?
