[src/trunk]: src/sys/dev/pci vioif(4): remove unnecessary lock acquirement

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

details:   https://anonhg.NetBSD.org/src/rev/59db506035a0
branches:  trunk
changeset: 364609:59db506035a0
user:      yamaguchi <yamaguchi%NetBSD.org@localhost>
date:      Thu Mar 31 06:17:34 2022 +0000

description:
vioif(4): remove unnecessary lock acquirement

The lock was hold to wait for completion of interrupt handlers.
But, they are already stopped by rxq_stopping and txq_stopping
flags.

pointed out by riastradh@n.o, thanks.

diffstat:

 sys/dev/pci/if_vioif.c |  55 +++++++++++++------------------------------------
 1 files changed, 15 insertions(+), 40 deletions(-)

diffs (98 lines):

diff -r 201b9528a405 -r 59db506035a0 sys/dev/pci/if_vioif.c
--- a/sys/dev/pci/if_vioif.c    Thu Mar 31 03:26:33 2022 +0000
+++ b/sys/dev/pci/if_vioif.c    Thu Mar 31 06:17:34 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_vioif.c,v 1.76 2022/03/29 01:57:51 yamaguchi Exp $  */
+/*     $NetBSD: if_vioif.c,v 1.77 2022/03/31 06:17:34 yamaguchi Exp $  */
 
 /*
  * Copyright (c) 2020 The NetBSD Foundation, Inc.
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_vioif.c,v 1.76 2022/03/29 01:57:51 yamaguchi Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_vioif.c,v 1.77 2022/03/31 06:17:34 yamaguchi Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_net_mpsafe.h"
@@ -1211,34 +1211,6 @@
 }
 
 static void
-vioif_stop_rendezvous(struct vioif_softc *sc)
-{
-       struct vioif_txqueue *txq;
-       struct vioif_rxqueue *rxq;
-       int i;
-
-       /*
-        * stop all packet processing:
-        * 1. acquire a lock for queue to wait
-        *    for finish of interrupt handler
-        * 2. stop workqueue for packet processing
-        */
-
-       for (i =0; i < sc->sc_act_nvq_pairs; i++) {
-               txq = &sc->sc_txq[i];
-               rxq = &sc->sc_rxq[i];
-
-               mutex_enter(rxq->rxq_lock);
-               mutex_exit(rxq->rxq_lock);
-               vioif_work_wait(sc->sc_txrx_workqueue, &rxq->rxq_work);
-
-               mutex_enter(txq->txq_lock);
-               mutex_exit(txq->txq_lock);
-               vioif_work_wait(sc->sc_txrx_workqueue, &txq->txq_work);
-       }
-}
-
-static void
 vioif_stop(struct ifnet *ifp, int disable)
 {
        struct vioif_softc *sc = ifp->if_softc;
@@ -1248,31 +1220,34 @@
        struct vioif_ctrlqueue *ctrlq = &sc->sc_ctrlq;
        int i;
 
-       /* Take the locks to ensure that ongoing TX/RX finish */
-       for (i = 0; i < sc->sc_act_nvq_pairs; i++) {
+       /* disable interrupts */
+       vioif_disable_interrupt_vqpairs(sc);
+       if (sc->sc_has_ctrl)
+               virtio_stop_vq_intr(vsc, ctrlq->ctrlq_vq);
+
+       /*
+        * stop all packet processing:
+        * 1. stop interrupt handlers by rxq_stopping and txq_stopping
+        * 2. wait for stoping workqueue for packet processing
+        */
+       for (i =0; i < sc->sc_act_nvq_pairs; i++) {
                txq = &sc->sc_txq[i];
                rxq = &sc->sc_rxq[i];
 
                mutex_enter(rxq->rxq_lock);
                rxq->rxq_stopping = true;
                mutex_exit(rxq->rxq_lock);
+               vioif_work_wait(sc->sc_txrx_workqueue, &rxq->rxq_work);
 
                mutex_enter(txq->txq_lock);
                txq->txq_stopping = true;
                mutex_exit(txq->txq_lock);
+               vioif_work_wait(sc->sc_txrx_workqueue, &txq->txq_work);
        }
 
-       /* disable interrupts */
-       vioif_disable_interrupt_vqpairs(sc);
-
-       if (sc->sc_has_ctrl)
-               virtio_stop_vq_intr(vsc, ctrlq->ctrlq_vq);
-
        /* only way to stop I/O and DMA is resetting... */
        virtio_reset(vsc);
 
-       vioif_stop_rendezvous(sc);
-
        for (i = 0; i < sc->sc_act_nvq_pairs; i++) {
                vioif_rx_queue_clear(&sc->sc_rxq[i]);
                vioif_tx_queue_clear(&sc->sc_txq[i]);