[src/trunk]: src/sys/dev/scsipi The mutex passed to cv_wait must also be held...

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

details:   https://anonhg.NetBSD.org/src/rev/57282f17f27e
branches:  trunk
changeset: 349670:57282f17f27e
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Sun Dec 18 13:59:14 2016 +0000

description:
The mutex passed to cv_wait must also be held when calling cv_broadcast.
Also optimizing mutex handling in completion thread.

>From nick@.

diffstat:

 sys/dev/scsipi/scsipi_base.c |  16 ++++++----------
 1 files changed, 6 insertions(+), 10 deletions(-)

diffs (87 lines):

diff -r 93ad51c721e2 -r 57282f17f27e sys/dev/scsipi/scsipi_base.c
--- a/sys/dev/scsipi/scsipi_base.c      Sun Dec 18 12:02:37 2016 +0000
+++ b/sys/dev/scsipi/scsipi_base.c      Sun Dec 18 13:59:14 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: scsipi_base.c,v 1.170 2016/12/16 15:00:52 mlelstv Exp $        */
+/*     $NetBSD: scsipi_base.c,v 1.171 2016/12/18 13:59:14 mlelstv Exp $        */
 
 /*-
  * Copyright (c) 1998, 1999, 2000, 2002, 2003, 2004 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: scsipi_base.c,v 1.170 2016/12/16 15:00:52 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: scsipi_base.c,v 1.171 2016/12/18 13:59:14 mlelstv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_scsi.h"
@@ -1462,8 +1462,8 @@
         * completion queue, and wake up the completion thread.
         */
        TAILQ_INSERT_TAIL(&chan->chan_complete, xs, channel_q);
+       cv_broadcast(chan_cv_complete(chan));
        mutex_exit(chan_mtx(chan));
-       cv_broadcast(chan_cv_complete(chan));
 
  out:
        /*
@@ -2138,21 +2138,17 @@
 
        mutex_enter(chan_mtx(chan));
        chan->chan_flags |= SCSIPI_CHAN_TACTIVE;
-       mutex_exit(chan_mtx(chan));
        for (;;) {
-               mutex_enter(chan_mtx(chan));
                xs = TAILQ_FIRST(&chan->chan_complete);
                if (xs == NULL && chan->chan_tflags  == 0) {
                        /* nothing to do; wait */
                        cv_wait(chan_cv_complete(chan), chan_mtx(chan));
-                       mutex_exit(chan_mtx(chan));
                        continue;
                }
                if (chan->chan_tflags & SCSIPI_CHANT_CALLBACK) {
                        /* call chan_callback from thread context */
                        chan->chan_tflags &= ~SCSIPI_CHANT_CALLBACK;
                        chan->chan_callback(chan, chan->chan_callback_arg);
-                       mutex_exit(chan_mtx(chan));
                        continue;
                }
                if (chan->chan_tflags & SCSIPI_CHANT_GROWRES) {
@@ -2164,6 +2160,7 @@
                        scsipi_channel_thaw(chan, 1);
                        if (chan->chan_tflags & SCSIPI_CHANT_GROWRES)
                                kpause("scsizzz", FALSE, hz/10, NULL);
+                       mutex_enter(chan_mtx(chan));
                        continue;
                }
                if (chan->chan_tflags & SCSIPI_CHANT_KICK) {
@@ -2171,10 +2168,10 @@
                        chan->chan_tflags &= ~SCSIPI_CHANT_KICK;
                        mutex_exit(chan_mtx(chan));
                        scsipi_run_queue(chan);
+                       mutex_enter(chan_mtx(chan));
                        continue;
                }
                if (chan->chan_tflags & SCSIPI_CHANT_SHUTDOWN) {
-                       mutex_exit(chan_mtx(chan));
                        break;
                }
                if (xs) {
@@ -2191,8 +2188,6 @@
                         * for some reason.
                         */
                        scsipi_run_queue(chan);
-               } else {
-                       mutex_exit(chan_mtx(chan));
                }
        }
 
@@ -2200,6 +2195,7 @@
 
        /* In case parent is waiting for us to exit. */
        cv_broadcast(chan_cv_thread(chan));
+       mutex_exit(chan_mtx(chan));
 
        kthread_exit(0);
 }