Ed,
On Tue, Sep 25, 2012 at 10:10:14PM +0000, Ed Maste wrote:
E> Author: emaste
E> Date: Tue Sep 25 22:10:14 2012
E> New Revision: 240938
E> URL: http://svn.freebsd.org/changeset/base/240938
E>
E> Log:
E> Avoid INVARIANTS panic destroying an in-use tap(4)
E>
E> The requirement (implied by the KASSERT in tap_destroy) that the tap is
E> closed isn't valid; destroy_dev will block in devdrn while other threads
E> are in d_* functions.
E>
E> Note: if_tun had the same issue, addressed in SVN revisions r186391,
E> r186483 and r186497. The use of the condvar there appears to be
E> redundant with the functionality provided by destroy_dev.
So why did you add condvar to the softc? See it in diff below.
E> Sponsored by: ADARA Networks
E> Reviewed by: dwhite
E> MFC after: 2 weeks
E>
E> Modified:
E> head/sys/net/if_tap.c
E> head/sys/net/if_tapvar.h
E>
E> Modified: head/sys/net/if_tap.c
E>
==============================================================================
E> --- head/sys/net/if_tap.c Tue Sep 25 21:33:36 2012 (r240937)
E> +++ head/sys/net/if_tap.c Tue Sep 25 22:10:14 2012 (r240938)
E> @@ -213,14 +213,10 @@ tap_destroy(struct tap_softc *tp)
E> {
E> struct ifnet *ifp = tp->tap_ifp;
E>
E> - /* Unlocked read. */
E> - KASSERT(!(tp->tap_flags & TAP_OPEN),
E> - ("%s flags is out of sync", ifp->if_xname));
E> -
E> CURVNET_SET(ifp->if_vnet);
E> + destroy_dev(tp->tap_dev);
E> seldrain(&tp->tap_rsel);
E> knlist_destroy(&tp->tap_rsel.si_note);
E> - destroy_dev(tp->tap_dev);
E> ether_ifdetach(ifp);
E> if_free(ifp);
E>
E>
E> Modified: head/sys/net/if_tapvar.h
E>
==============================================================================
E> --- head/sys/net/if_tapvar.h Tue Sep 25 21:33:36 2012 (r240937)
E> +++ head/sys/net/if_tapvar.h Tue Sep 25 22:10:14 2012 (r240938)
E> @@ -64,6 +64,7 @@ struct tap_softc {
E> SLIST_ENTRY(tap_softc) tap_next; /* next device in chain */
E> struct cdev *tap_dev;
E> struct mtx tap_mtx; /* per-softc mutex */
E> + struct cv tap_cv; /* protect ref'd dev destroy */
E> };
E>
E> #endif /* !_NET_IF_TAPVAR_H_ */
--
Totus tuus, Glebius.
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