[src/trunk]: src/sys/kern Make sure we hold alldevs_mtx for access to alldevs...

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

details:   https://anonhg.NetBSD.org/src/rev/a799da8fcf93
branches:  trunk
changeset: 822427:a799da8fcf93
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Mar 20 00:30:03 2017 +0000

description:
Make sure we hold alldevs_mtx for access to alldevs in deviter.

- Extend alldevs_mtx section in deviter_init.
- Assert ownership of alldevs_mtx in private functions:
  . deviter_reinit
  . deviter_next1
  . deviter_next2
- Acquire alldevs_mtx in deviter_next.

(alldevs_mtx is not relevant to the struct deviter object, which is
private to the caller who must guarantee exclusive access to it.)

diffstat:

 sys/kern/subr_autoconf.c |  29 ++++++++++++++++++++---------
 1 files changed, 20 insertions(+), 9 deletions(-)

diffs (116 lines):

diff -r 0dd75c61e17b -r a799da8fcf93 sys/kern/subr_autoconf.c
--- a/sys/kern/subr_autoconf.c  Sun Mar 19 23:47:46 2017 +0000
+++ b/sys/kern/subr_autoconf.c  Mon Mar 20 00:30:03 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_autoconf.c,v 1.247 2016/07/19 07:44:03 msaitoh Exp $ */
+/* $NetBSD: subr_autoconf.c,v 1.248 2017/03/20 00:30:03 riastradh Exp $ */
 
 /*
  * Copyright (c) 1996, 2000 Christopher G. Demetriou
@@ -77,7 +77,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.247 2016/07/19 07:44:03 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.248 2017/03/20 00:30:03 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
@@ -2781,17 +2781,15 @@
 
        memset(di, 0, sizeof(*di));
 
-       mutex_enter(&alldevs_mtx);
        if ((flags & DEVITER_F_SHUTDOWN) != 0)
                flags |= DEVITER_F_RW;
 
+       mutex_enter(&alldevs_mtx);
        if ((flags & DEVITER_F_RW) != 0)
                alldevs_nwrite++;
        else
                alldevs_nread++;
        di->di_gen = alldevs_gen++;
-       mutex_exit(&alldevs_mtx);
-
        di->di_flags = flags;
 
        switch (di->di_flags & (DEVITER_F_LEAVES_FIRST|DEVITER_F_ROOT_FIRST)) {
@@ -2814,11 +2812,14 @@
        }
 
        deviter_reinit(di);
+       mutex_exit(&alldevs_mtx);
 }
 
 static void
 deviter_reinit(deviter_t *di)
 {
+
+       KASSERT(mutex_owned(&alldevs_mtx));
        if ((di->di_flags & DEVITER_F_RW) != 0)
                di->di_prev = TAILQ_LAST(&alldevs, devicelist);
        else
@@ -2828,6 +2829,7 @@
 device_t
 deviter_first(deviter_t *di, deviter_flags_t flags)
 {
+
        deviter_init(di, flags);
        return deviter_next(di);
 }
@@ -2837,6 +2839,8 @@
 {
        device_t dv;
 
+       KASSERT(mutex_owned(&alldevs_mtx));
+
        dv = di->di_prev;
 
        if (dv == NULL)
@@ -2855,6 +2859,8 @@
 {
        device_t dv;
 
+       KASSERT(mutex_owned(&alldevs_mtx));
+
        do {
                dv = deviter_next2(di);
        } while (dv != NULL && !deviter_visits(di, dv));
@@ -2867,9 +2873,11 @@
 {
        device_t dv = NULL;
 
+       mutex_enter(&alldevs_mtx);
        switch (di->di_flags & (DEVITER_F_LEAVES_FIRST|DEVITER_F_ROOT_FIRST)) {
        case 0:
-               return deviter_next1(di);
+               dv = deviter_next1(di);
+               break;
        case DEVITER_F_LEAVES_FIRST:
                while (di->di_curdepth >= 0) {
                        if ((dv = deviter_next1(di)) == NULL) {
@@ -2878,7 +2886,7 @@
                        } else if (dv->dv_depth == di->di_curdepth)
                                break;
                }
-               return dv;
+               break;
        case DEVITER_F_ROOT_FIRST:
                while (di->di_curdepth <= di->di_maxdepth) {
                        if ((dv = deviter_next1(di)) == NULL) {
@@ -2887,10 +2895,13 @@
                        } else if (dv->dv_depth == di->di_curdepth)
                                break;
                }
-               return dv;
+               break;
        default:
-               return NULL;
+               break;
        }
+       mutex_exit(&alldevs_mtx);
+
+       return dv;
 }
 
 void