rtwn: ensure TX work isn't scheduled during reset / abort

Don't schedule work during reset / abort.  For USB NICs, work
must not be scheduled during a call to rtwn_usb_abort_xfers(),
as then it'll cause the call to usbd_transfer_drain() to hang.

This fixes a hang I've been seeing where the NIC hits a TX timeout
and then the reset/re-init path is called.  If data is scheduled
to be transmitted in that window, the call to usbd_transfer_drain()
would hang and require a hard reboot to recover.

Differential Revision: https://reviews.freebsd.org/D47479

1 files changed, 5 insertions, 0 deletions

diff --git a/sys/dev/rtwn/if_rtwn_tx.c b/sys/dev/rtwn/if_rtwn_tx.c
index f5e97933b314..bf45d14f7edc 100644
--- a/sys/dev/rtwn/if_rtwn_tx.c
+++ b/sys/dev/rtwn/if_rtwn_tx.c
@@ -263,6 +263,11 @@ rtwn_start(struct rtwn_softc *sc)
 	struct mbuf *m;
 
 	RTWN_ASSERT_LOCKED(sc);
+
+	/* Ensure no work is scheduled during reset/teardown */
+	if ((sc->sc_flags & RTWN_RUNNING) == 0)
+		return;
+
 	while ((m = mbufq_dequeue(&sc->sc_snd)) != NULL) {
 		if (sc->qfullmsk != 0) {
 			mbufq_prepend(&sc->sc_snd, m);