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Fri, 13 Aug 2021 10:00:37 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: wat) by smtp.codeaurora.org (Postfix) with ESMTPSA id 10E49C433F1; Fri, 13 Aug 2021 10:00:34 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Fri, 13 Aug 2021 18:00:34 +0800 From: wat@codeaurora.org To: undisclosed-recipients:; Subject: Re: [PATCH] usb: xhci-ring: set all cancelled_td's cancel_status to TD_CLEARING_CACHE In-Reply-To: <39525c12-e8f3-8587-5714-5a22ca1e8e4f@linux.intel.com> References: <1628822604-29239-1-git-send-email-wat@codeaurora.org> <39525c12-e8f3-8587-5714-5a22ca1e8e4f@linux.intel.com> Message-ID: X-Sender: wat@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 2021-08-13 17:09, Mathias Nyman wrote: > On 13.8.2021 11.44, wat@codeaurora.org wrote: >> On 2021-08-13 15:25, Ikjoon Jang wrote: >>> Hi, >>> >>> On Fri, Aug 13, 2021 at 10:44 AM Tao Wang wrote: >>>> >>>> USB SSD may fail to unmount if disconnect during data transferring. >>>> >>>> it stuck in usb_kill_urb() due to urb use_count will not become >>>> zero, >>>> this means urb giveback is not happen. >>>> in xhci_handle_cmd_set_deq() will giveback urb if td's cancel_status >>>> equal to TD_CLEARING_CACHE, >>>> but in xhci_invalidate_cancelled_tds(), only last canceled td's >>>> cancel_status change to TD_CLEARING_CACHE, >>>> thus giveback only happen to last urb. >>>> >>>> this change set all cancelled_td's cancel_status to >>>> TD_CLEARING_CACHE >>>> rather than the last one, so all urb can giveback. >>>> >>>> Signed-off-by: Tao Wang >>>> --- >>>>  drivers/usb/host/xhci-ring.c | 24 ++++++++++++------------ >>>>  1 file changed, 12 insertions(+), 12 deletions(-) >>>> >>>> diff --git a/drivers/usb/host/xhci-ring.c >>>> b/drivers/usb/host/xhci-ring.c >>>> index 8fea44b..c7dd7c0 100644 >>>> --- a/drivers/usb/host/xhci-ring.c >>>> +++ b/drivers/usb/host/xhci-ring.c >>>> @@ -960,19 +960,19 @@ static int >>>> xhci_invalidate_cancelled_tds(struct xhci_virt_ep *ep) >>>>                         td_to_noop(xhci, ring, td, false); >>>>                         td->cancel_status = TD_CLEARED; >>>>                 } >>>> -       } >>>> -       if (cached_td) { >>>> -               cached_td->cancel_status = TD_CLEARING_CACHE; >>>> - >>>> -               err = xhci_move_dequeue_past_td(xhci, slot_id, >>>> ep->ep_index, >>>> -                                               >>>> cached_td->urb->stream_id, >>>> -                                               cached_td); >>>> -               /* Failed to move past cached td, try just setting >>>> it noop */ >>>> -               if (err) { >>>> -                       td_to_noop(xhci, ring, cached_td, false); >>>> -                       cached_td->cancel_status = TD_CLEARED; >>>> +               if (cached_td) { >>>> +                       cached_td->cancel_status = >>>> TD_CLEARING_CACHE; >>>> + >>>> +                       err = xhci_move_dequeue_past_td(xhci, >>>> slot_id, ep->ep_index, >>>> +                                                       >>>> cached_td->urb->stream_id, >>>> +                                                       cached_td); >>>> +                       /* Failed to move past cached td, try just >>>> setting it noop */ >>>> +                       if (err) { >>>> +                               td_to_noop(xhci, ring, cached_td, >>>> false); >>>> +                               cached_td->cancel_status = >>>> TD_CLEARED; >>>> +                       } >>>> +                       cached_td = NULL; >>>>                 } >>>> -               cached_td = NULL; >>> >>> I think we can call xhci_move_dequeue_past_td() just once to >>> the last halted && cancelled TD in a ring. >>> >>> But that might need to compare two TDs to see which one is >>> the latter, I'm not sure how to do this well. :-/ >>> >>> if (!cached_td || cached_td < td) >>>   cached_td = td; >>> >> >> thanks, I think you are correct that we can call >> xhci_move_dequeue_past_td() just once to >>  the last halted && cancelled TD in a ring, >> but the set status "cached_td->cancel_status = TD_CLEARING_CACHE;" >> should be every cancelled TD. >> I am not very good at td and ring, I have a question why we need to >> compare two TDs to see which one is the latter. > > I'm debugging the exact same issue. > For normal endpoints (no streams) it should be enough to set > cancel_td->cancel_status = TD_CLEARING_CACHE > in the TD_DIRTY and TD_HALTED case. > > We don't need to move the dq past the last cancelled TD as other > cancelled TDs are set to no-op, and > the command to move the dq will flush the xHC controllers TD cache and > read the no-ops. > (just make sure we call xhci_move_dequeue_past_td() _after_ > overwriting cancelled TDs with no-op) > > Streams get trickier as each endpoint has several rings, and we might > need to move the dq pointer for > many stream rings on that endpoint. This needs more work as we > shouldn't start the endpoint before all > the all move dq commands complete. i.e. the current ep->ep_state &= > ~SET_DEQ_PENDING isn't enough. > > -Mathias ok, thanks, please tell me if you have a great solution after debugging, I still need to learn from you.