[src/trunk]: src/sys/dev/usb xhci(4): Handle race between software abort and ...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b926ded0b6e0
branches:  trunk
changeset: 366107:b926ded0b6e0
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat May 14 19:44:37 2022 +0000

description:
xhci(4): Handle race between software abort and hardware stall.

diffstat:

 sys/dev/usb/xhci.c |  30 ++++++++++++++++++++++++++----
 1 files changed, 26 insertions(+), 4 deletions(-)

diffs (58 lines):

diff -r 53359113608e -r b926ded0b6e0 sys/dev/usb/xhci.c
--- a/sys/dev/usb/xhci.c        Sat May 14 19:44:26 2022 +0000
+++ b/sys/dev/usb/xhci.c        Sat May 14 19:44:37 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: xhci.c,v 1.165 2022/05/14 19:44:26 riastradh Exp $     */
+/*     $NetBSD: xhci.c,v 1.166 2022/05/14 19:44:37 riastradh Exp $     */
 
 /*
  * Copyright (c) 2013 Jonathan A. Kollasch
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xhci.c,v 1.165 2022/05/14 19:44:26 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xhci.c,v 1.166 2022/05/14 19:44:37 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -2253,6 +2253,10 @@
        struct xhci_ring * const tr = xs->xs_xr[dci];
        struct usbd_xfer *xfer;
 
+       XHCIHIST_FUNC();
+       XHCIHIST_CALLARGS("sc=%#jx pipe=%#jx",
+           (uintptr_t)sc, (uintptr_t)pipe, 0, 0);
+
        mutex_enter(&sc->sc_lock);
 
        xhci_pipe_restart(pipe);
@@ -2263,8 +2267,26 @@
         */
        tr->is_halted = false;
        xfer = SIMPLEQ_FIRST(&pipe->up_queue);
-       if (xfer)
-               (*pipe->up_methods->upm_start)(xfer);
+       if (xfer) {
+               /*
+                * If the first xfer of the queue is not in progress,
+                * though, there may be a concurrent software abort
+                * that has already cancelled it and is now in the
+                * middle of a concurrent xhci_pipe_restart waiting to
+                * reacquire the pipe (bus) lock.  So only restart the
+                * xfer if it's still USBD_IN_PROGRESS.
+                *
+                * Either way, xfers on the queue can't be in
+                * USBD_NOT_STARTED.
+                */
+               KASSERT(xfer->ux_status != USBD_NOT_STARTED);
+               if (xfer->ux_status == USBD_IN_PROGRESS) {
+                       (*pipe->up_methods->upm_start)(xfer);
+               } else {
+                       DPRINTF("pipe restart race xfer=%#jx status=%jd",
+                           (uintptr_t)xfer, xfer->ux_status, 0, 0);
+               }
+       }
 
        mutex_exit(&sc->sc_lock);
 }