Hi Kalle,
>
> ----------------------------------------------------------------------
> Ganapathi Bhat <gbhat@xxxxxxxxxxx> wrote:
>
> > From: Shrenik Shikhare <shrenik@xxxxxxxxxxx>
> >
> > There is a race condition for acquiring rx_proc_lock between rx worker
> > thread and USB RX data interrupt
> > (mwifiex_usb_rx_complete):
> >
> > 1. USB receives an RX data interrupt, queues rx_work 2. rx_work
> > empties rx_data_q, tries to acquire rx_proc_lock (to clear
> > rx_processing flag) 3. While #2 is yet to acquire rx_proc_lock, driver
> > receives continuous RX data interupts(mwifiex_usb_rx_complete)
> > 3. For each interrupt at #3, driver acquires rx_proc_lock(it gets the
> > lock since it is in interrupt context), tries to queue rx_work, but
> > fails to do so since rx_processing is still set(#2) 4. When rx_pending
> > exceeds HIGH_RX_PENDING, driver stops submitting URBs back to USB
> > subsystem and thus firmware stops uploading RX data to driver 5. Now
> > finally #2 will acquire rx_proc_lock, but because of #4, there are no
> > further triggers to schedule rx_work again
> >
> > The above scenario occurs in some platforms where the RX processing is
> > comparitively slower. This results in RX stall in driver, command/TX
> > timeouts in firmware. The above scenario is introduced after commit
> > c7dbdcb2a4e1
> > ("mwifiex: schedule rx_work on RX interrupt for USB")
> >
> > To fix this set a new more_rx_task_flag whenever RX data callback is
> > trying to schedule rx_work but rx_processing is not yet cleared. This
> > will let the current rx_work(which was waiting for
> > rx_proc_lock) to loopback and process newly arrived RX packets.
> >
> > Signed-off-by: Cathy Luo <cluo@xxxxxxxxxxx>
> > Signed-off-by: Ganapathi Bhat <gbhat@xxxxxxxxxxx>
>
> I can't find any commit with id c7dbdcb2a4e1, is it correct?
Correct. Actually the commit id c7dbdcb2a4e1 is the PATCH [1/2] sent in this series.
>
> --
> https://patchwork.kernel.org/patch/10178729/
>
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingp
> atches
Regards,
Ganapathi
