Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx> wrote: > The USB driver uses four USB Request Blocks for RX. Before submitting > one, it allocates a 32768 byte skb for the RX data. This allocation can > fail, maybe due to temporary memory fragmentation. When the allocation > fails, the corresponding URB is never submitted again. After four such > allocation failures, all RX stops because the driver is not requesting > data from the device anymore. > > Don't allocate a 32768 byte skb when submitting a USB Request Block > (which happens very often). Instead preallocate 8 such skbs, and reuse > them over and over. If all 8 are busy, allocate a new one. This is > pretty rare. If the allocation fails, use a work to try again later. > When there are enough free skbs again, free the excess skbs. > > Also, use WQ_BH for the RX workqueue. With a normal or high priority > workqueue the skbs are processed too slowly when the system is even a > little busy, like when opening a new page in a browser, and the driver > runs out of free skbs and allocates a lot of new ones. > > This is more or less what the out-of-tree Realtek drivers do, except > they use a tasklet instead of a BH workqueue. > > Tested with RTL8723DU, RTL8821AU, RTL8812AU, RTL8812BU, RTL8822CU, > RTL8811CU. > > Closes: https://lore.kernel.org/linux-wireless/6e7ecb47-7ea0-433a-a19f-05f88a2edf6b@xxxxxxxxx/ > Signed-off-by: Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx> Acked-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx> > > - error = usb_submit_urb(rxcb->rx_urb, GFP_ATOMIC); > + error = usb_submit_urb(rxcb->rx_urb, gfp); > if (error) { > - kfree_skb(rxcb->rx_skb); > + skb_queue_tail(&rtwusb->rx_free_queue, rxcb->rx_skb); > + > if (error != -ENODEV) > rtw_err(rtwdev, "Err sending rx data urb %d\n", > error); Looking into usb_submit_urb(), I think ENODEV means USB device becomes unavailable. For this case, it seems well for rxcb missed to attach RX URB anymore, not 'goto try_later'. > + > + if (error == -ENOMEM) > + goto try_later; > + } > + > + return; > + > +try_later: > + rxcb->rx_skb = NULL; > + queue_work(rtwusb->rxwq, &rtwusb->rx_urb_work); > +}
