introduce a new kern.autoconf_serial sysctl that can be used by userland

to monitor state changes of the kernel device tree

input from dnd ok dlg@, deraadt@

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index abf9cf0..ff42ebb 100644 (file)
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: kern_sysctl.c,v 1.407 2022/11/05 19:29:46 cheloha Exp $       */
+/*     $OpenBSD: kern_sysctl.c,v 1.408 2022/11/07 14:25:44 robert Exp $        */
 /*     $NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $     */
 
 /*-
@@ -126,6 +126,7 @@ extern long numvnodes;
 extern int allowdt;
 extern int audio_record_enable;
 extern int video_record_enable;
+extern int autoconf_serial;
 
 int allowkmem;
 
@@ -341,6 +342,7 @@ const struct sysctl_bounded_args kern_vars[] = {
 #ifdef PTRACE
        {KERN_GLOBAL_PTRACE, &global_ptrace, 0, 1},
 #endif
+       {KERN_AUTOCONF_SERIAL, &autoconf_serial, SYSCTL_INT_READONLY},
 };
 
 int

diff --git a/sys/kern/subr_autoconf.c b/sys/kern/subr_autoconf.c
index a35b222..4163314 100644 (file)
--- a/sys/kern/subr_autoconf.c
+++ b/sys/kern/subr_autoconf.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: subr_autoconf.c,v 1.96 2022/04/07 09:37:32 tb Exp $   */
+/*     $OpenBSD: subr_autoconf.c,v 1.97 2022/11/07 14:25:44 robert Exp $       */
 /*     $NetBSD: subr_autoconf.c,v 1.21 1996/04/04 06:06:18 cgd Exp $   */
 
 /*
@@ -106,6 +106,11 @@ struct mutex autoconf_attdet_mtx = MUTEX_INITIALIZER(IPL_HIGH);
  */
 int    autoconf_attdet;
 
+/*
+ * Versioned state of the devices tree so that changes can be detected.
+ */
+unsigned int autoconf_serial = 0;
+
 /*
  * Initialize autoconfiguration data structures.  This occurs before console
  * initialization as that might require use of this subsystem.  Furthermore
@@ -419,6 +424,7 @@ config_attach(struct device *parent, void *match, void *aux, cfprint_t print)
        mtx_enter(&autoconf_attdet_mtx);
        if (--autoconf_attdet == 0)
                wakeup(&autoconf_attdet);
+       autoconf_serial++;
        mtx_leave(&autoconf_attdet_mtx);
        return (dev);
 }
@@ -642,6 +648,7 @@ done:
        mtx_enter(&autoconf_attdet_mtx);
        if (++autoconf_attdet == 0)
                wakeup(&autoconf_attdet);
+       autoconf_serial++;
        mtx_leave(&autoconf_attdet_mtx);
        return (rv);
 }

diff --git a/sys/sys/sysctl.h b/sys/sys/sysctl.h
index 8456478..4fa5afd 100644 (file)
--- a/sys/sys/sysctl.h
+++ b/sys/sys/sysctl.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: sysctl.h,v 1.230 2022/11/05 19:29:46 cheloha Exp $    */
+/*     $OpenBSD: sysctl.h,v 1.231 2022/11/07 14:25:44 robert Exp $     */
 /*     $NetBSD: sysctl.h,v 1.16 1996/04/09 20:55:36 cgd Exp $  */
 
 /*
@@ -192,7 +192,8 @@ struct ctlname {
 #define        KERN_UTC_OFFSET         88      /* int: adjust RTC time to UTC */
 #define        KERN_VIDEO              89      /* struct: video properties */
 #define        KERN_CLOCKINTR          90      /* node: clockintr */
-#define        KERN_MAXID              91      /* number of valid kern ids */
+#define        KERN_AUTOCONF_SERIAL    91      /* int: kernel device tree state serial */
+#define        KERN_MAXID              92      /* number of valid kern ids */
 
 #define        CTL_KERN_NAMES { \
        { 0, 0 }, \
@@ -286,6 +287,7 @@ struct ctlname {
        { "utc_offset", CTLTYPE_INT }, \
        { "video", CTLTYPE_STRUCT }, \
        { "clockintr", CTLTYPE_NODE }, \
+       { "autoconf_serial", CTLTYPE_INT }, \
 }
 
 /*