git.openwrt.org Git - openwrt/staging/blocktrron.git/blob

   1 From 18f08bf8df95c687d6fee3d2bb747cbd2fa0b878 Mon Sep 17 00:00:00 2001
   2 From: Jonathan Bell <jonathan@raspberrypi.com>
   3 Date: Thu, 22 Sep 2022 14:55:54 +0100
   4 Subject: [PATCH] usb: xhci: account for num_trbs_free when
   5  invalidating TDs
   6
   7 If a ring has a number of TDs enqueued past the dequeue pointer, and the
   8 URBs corresponding to these TDs are dequeued, then num_trbs_free isn't
   9 updated to show that these TDs have been converted to no-ops and
  10 effectively "freed". This means that num_trbs_free creeps downwards
  11 until the count is exhausted, which then triggers xhci_ring_expansion()
  12 and effectively leaks memory by infinitely growing the transfer ring.
  13
  14 This is commonly encounted through the use of a usb-serial port where
  15 the port is repeatedly opened, read, then closed.
  16
  17 Move the num_trbs_free crediting out of the Set TR Dequeue Pointer
  18 handling and into xhci_invalidate_cancelled_tds().
  19
  20 There is a potential for overestimating the actual space on the ring if
  21 the ring is nearly full and TDs are arbitrarily enqueued by a device
  22 driver while it is dequeueing them, but dequeues are usually batched
  23 during device close/shutdown or endpoint error recovery.
  24
  25 See https://github.com/raspberrypi/linux/issues/5088
  26
  27 Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
  28 ---
  29  drivers/usb/host/xhci-ring.c | 14 +++-----------
  30  1 file changed, 3 insertions(+), 11 deletions(-)
  31
  32 --- a/drivers/usb/host/xhci-ring.c
  33 +++ b/drivers/usb/host/xhci-ring.c
  34 @@ -1035,11 +1035,13 @@ static int xhci_invalidate_cancelled_tds
  35                                                  td->urb->stream_id, td->urb,
  36                                                  cached_td->urb->stream_id, cached_td->urb);
  37                                 cached_td = td;
  38 +                               ring->num_trbs_free += td->num_trbs;
  39                                 break;
  40                         }
  41                 } else {
  42                         td_to_noop(xhci, ring, td, false);
  43                         td->cancel_status = TD_CLEARED;
  44 +                       ring->num_trbs_free += td->num_trbs;
  45                 }
  46         }
  47
  48 @@ -1287,10 +1289,7 @@ static void update_ring_for_set_deq_comp
  49                 unsigned int ep_index)
  50  {
  51         union xhci_trb *dequeue_temp;
  52 -       int num_trbs_free_temp;
  53 -       bool revert = false;
  54
  55 -       num_trbs_free_temp = ep_ring->num_trbs_free;
  56         dequeue_temp = ep_ring->dequeue;
  57
  58         /* If we get two back-to-back stalls, and the first stalled transfer
  59 @@ -1305,8 +1304,6 @@ static void update_ring_for_set_deq_comp
  60         }
  61
  62         while (ep_ring->dequeue != dev->eps[ep_index].queued_deq_ptr) {
  63 -               /* We have more usable TRBs */
  64 -               ep_ring->num_trbs_free++;
  65                 ep_ring->dequeue++;
  66                 if (trb_is_link(ep_ring->dequeue)) {
  67                         if (ep_ring->dequeue ==
  68 @@ -1316,15 +1313,10 @@ static void update_ring_for_set_deq_comp
  69                         ep_ring->dequeue = ep_ring->deq_seg->trbs;
  70                 }
  71                 if (ep_ring->dequeue == dequeue_temp) {
  72 -                       revert = true;
  73 +                       xhci_dbg(xhci, "Unable to find new dequeue pointer\n");
  74                         break;
  75                 }
  76         }
  77 -
  78 -       if (revert) {
  79 -               xhci_dbg(xhci, "Unable to find new dequeue pointer\n");
  80 -               ep_ring->num_trbs_free = num_trbs_free_temp;
  81 -       }
  82  }
  83
  84  /*