[src/trunk]: src/sys/dev/usb usbnet: Refuse to bring interfaces back up once ...

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

details:   https://anonhg.NetBSD.org/src/rev/af89d25ed3c6
branches:  trunk
changeset: 362497:af89d25ed3c6
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Thu Mar 03 05:48:37 2022 +0000

description:
usbnet: Refuse to bring interfaces back up once dying.

Make this happen uniformly across all usbnet drivers, not on a
per-driver basis.

This ensures new activity on the interface can't happen by the time
we have stopped existing activity and waited for it to complete.

diffstat:

 sys/dev/usb/usbnet.c |  23 +++++++++++++++++++++--
 1 files changed, 21 insertions(+), 2 deletions(-)

diffs (58 lines):

diff -r 32263407adc7 -r af89d25ed3c6 sys/dev/usb/usbnet.c
--- a/sys/dev/usb/usbnet.c      Thu Mar 03 05:48:30 2022 +0000
+++ b/sys/dev/usb/usbnet.c      Thu Mar 03 05:48:37 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: usbnet.c,v 1.57 2022/03/03 05:48:30 riastradh Exp $    */
+/*     $NetBSD: usbnet.c,v 1.58 2022/03/03 05:48:37 riastradh Exp $    */
 
 /*
  * Copyright (c) 2019 Matthew R. Green
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: usbnet.c,v 1.57 2022/03/03 05:48:30 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: usbnet.c,v 1.58 2022/03/03 05:48:37 riastradh Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -1289,9 +1289,20 @@
 {
        USBNETHIST_FUNC(); USBNETHIST_CALLED();
        struct usbnet * const un = ifp->if_softc;
+       bool dying;
 
        KASSERTMSG(IFNET_LOCKED(ifp), "%s", ifp->if_xname);
 
+       /*
+        * Prevent anyone from bringing the interface back up once
+        * we're detaching.
+        */
+       mutex_enter(&un->un_pri->unp_core_lock);
+       dying = un->un_pri->unp_dying;
+       mutex_exit(&un->un_pri->unp_core_lock);
+       if (dying)
+               return EIO;
+
        return uno_init(un, ifp);
 }
 
@@ -1572,10 +1583,18 @@
        struct ifnet * const ifp = usbnet_ifp(un);
        struct mii_data * const mii = usbnet_mii(un);
 
+       /*
+        * Prevent new activity.  After we stop the interface, it
+        * cannot be brought back up.
+        */
        mutex_enter(&unp->unp_core_lock);
        unp->unp_dying = true;
        mutex_exit(&unp->unp_core_lock);
 
+       /*
+        * If we're still running on the network, stop and wait for all
+        * asynchronous activity to finish.
+        */
        IFNET_LOCK(ifp);
        if (ifp->if_flags & IFF_RUNNING) {
                usbnet_if_stop(ifp, 1);