[src/trunk]: src/sys/dev/usb Don't hold softc lock when calling ucom_read

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

details:   https://anonhg.NetBSD.org/src/rev/b0619b907fd8
branches:  trunk
changeset: 819698:b0619b907fd8
user:      skrll <skrll%NetBSD.org@localhost>
date:      Wed Dec 14 15:11:29 2016 +0000

description:
Don't hold softc lock when calling ucom_read

PR/51714: uftdi (on xhci): mutex_vector_enter: locking against myself

diffstat:

 sys/dev/usb/ucom.c |  14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diffs (42 lines):

diff -r 46cfa407a94e -r b0619b907fd8 sys/dev/usb/ucom.c
--- a/sys/dev/usb/ucom.c        Wed Dec 14 14:01:10 2016 +0000
+++ b/sys/dev/usb/ucom.c        Wed Dec 14 15:11:29 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ucom.c,v 1.117 2016/12/04 10:12:35 skrll Exp $ */
+/*     $NetBSD: ucom.c,v 1.118 2016/12/14 15:11:29 skrll Exp $ */
 
 /*
  * Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ucom.c,v 1.117 2016/12/04 10:12:35 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ucom.c,v 1.118 2016/12/14 15:11:29 skrll Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -1608,6 +1608,7 @@
                return;
        }
 
+       mutex_exit(&sc->sc_lock);
        if (sc->sc_methods->ucom_read != NULL) {
                sc->sc_methods->ucom_read(sc->sc_parent, sc->sc_portno,
                    &cp, &cc);
@@ -1617,6 +1618,15 @@
 
        ub->ub_len = cc;
 
+       mutex_enter(&sc->sc_lock);
+       if (sc->sc_dying) {
+               if (--sc->sc_refcnt < 0)
+                       cv_broadcast(&sc->sc_detachcv);
+               mutex_exit(&sc->sc_lock);
+               DPRINTF("... dying", 0, 0, 0, 0);
+               return;
+       }
+
        SIMPLEQ_INSERT_TAIL(&sc->sc_ibuff_full, ub, ub_link);
 
        ucom_read_complete(sc);