Revert r267961, r267973:

These changes prevent sysctl(8) from returning proper output,
such as:

 1) no output from sysctl(8)
 2) erroneously returning ENOMEM with tools like truss(1)
    or uname(1)
 truss: can not get etype: Cannot allocate memory

1 files changed, 44 insertions, 149 deletions

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index cb5a266e4e21..fec4aeabe1f5 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -98,13 +98,10 @@ static struct sx sysctlmemlock;
 
 static int sysctl_root(SYSCTL_HANDLER_ARGS);
 
-/* Root list */
-struct sysctl_oid_list sysctl__children = SLIST_HEAD_INITIALIZER(&sysctl__children);
+struct sysctl_oid_list sysctl__children; /* root list */
 
 static int	sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del,
 		    int recurse);
-static int	sysctl_old_kernel(struct sysctl_req *, const void *, size_t);
-static int	sysctl_new_kernel(struct sysctl_req *, void *, size_t);
 
 static struct sysctl_oid *
 sysctl_find_oidname(const char *name, struct sysctl_oid_list *list)
@@ -139,118 +136,6 @@ sysctl_unlock(void)
 	SYSCTL_XUNLOCK();
 }
 
-static int
-sysctl_root_handler_locked(struct sysctl_oid *oid, void *arg1, intptr_t arg2,
-    struct sysctl_req *req)
-{
-	int error;
-
-	oid->oid_running++;
-	SYSCTL_XUNLOCK();
-
-	if (!(oid->oid_kind & CTLFLAG_MPSAFE))
-		mtx_lock(&Giant);
-	error = oid->oid_handler(oid, arg1, arg2, req);
-	if (!(oid->oid_kind & CTLFLAG_MPSAFE))
-		mtx_unlock(&Giant);
-
-	SYSCTL_XLOCK();
-	oid->oid_running--;
-	if (oid->oid_running == 0 && (oid->oid_kind & CTLFLAG_DYING) != 0)
-		wakeup(&oid->oid_running);
-
-	return (error);
-}
-
-static void
-sysctl_load_tunable_by_oid_locked(struct sysctl_oid *oidp)
-{
-	struct sysctl_req req;
-	struct sysctl_oid *curr;
-	char *penv;
-	char path[64];
-	ssize_t rem = sizeof(path);
-	ssize_t len;
-	int val_int;
-	long val_long;
-	int64_t val_64;
-	int error;
-
-	path[--rem] = 0;
-
-	for (curr = oidp; curr != NULL; curr = SYSCTL_PARENT(curr)) {
-		len = strlen(curr->oid_name);
-		rem -= len;
-		if (curr != oidp)
-			rem -= 1;
-		if (rem < 0) {
-			printf("OID path exceeds %d bytes\n", (int)sizeof(path));
-			return;
-		}
-		memcpy(path + rem, curr->oid_name, len);
-		if (curr != oidp)
-			path[rem + len] = '.';
-	}
-
-	penv = getenv(path + rem);
-	if (penv == NULL)
-		return;
-
-	memset(&req, 0, sizeof(req));
-
-	req.td = curthread;
-	req.oldfunc = sysctl_old_kernel;
-	req.newfunc = sysctl_new_kernel;
-	req.lock = REQ_UNWIRED;
-
-	switch (oidp->oid_kind & CTLTYPE) {
-	case CTLTYPE_INT:
-		val_int = strtoq(penv, NULL, 0);
-		req.newlen = sizeof(val_int);
-		req.newptr = &val_int;
-		break;
-	case CTLTYPE_UINT:
-		val_int = strtouq(penv, NULL, 0);
-		req.newlen = sizeof(val_int);
-		req.newptr = &val_int;
-		break;
-	case CTLTYPE_LONG:
-		val_long = strtoq(penv, NULL, 0);
-		req.newlen = sizeof(val_long);
-		req.newptr = &val_long;
-		break;
-	case CTLTYPE_ULONG:
-		val_long = strtouq(penv, NULL, 0);
-		req.newlen = sizeof(val_long);
-		req.newptr = &val_long;
-		break;
-	case CTLTYPE_S64:
-		val_64 = strtoq(penv, NULL, 0);
-		req.newlen = sizeof(val_64);
-		req.newptr = &val_64;
-		break;
-	case CTLTYPE_U64:
-		val_64 = strtouq(penv, NULL, 0);
-		req.newlen = sizeof(val_64);
-		req.newptr = &val_64;
-		break;
-	case CTLTYPE_STRING:
-		req.newlen = strlen(penv);
-		req.newptr = penv;
-		break;
-	default:
-		freeenv(penv);
-		return;
-	}
-	error = sysctl_root_handler_locked(oidp, oidp->oid_arg1,
-	    oidp->oid_arg2, &req);
-	if (error != 0) {
-		printf("Setting sysctl '%s' to '%s' failed: %d\n",
-		    path, penv, error);
-	}
-	freeenv(penv);
-}
-
 void
 sysctl_register_oid(struct sysctl_oid *oidp)
 {
@@ -307,15 +192,6 @@ sysctl_register_oid(struct sysctl_oid *oidp)
 		SLIST_INSERT_AFTER(q, oidp, oid_link);
 	else
 		SLIST_INSERT_HEAD(parent, oidp, oid_link);
-
-	if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE &&
-#ifdef VIMAGE
-	    (oidp->oid_kind & CTLFLAG_VNET) == 0 &&
-#endif
-	    (oidp->oid_kind & CTLFLAG_TUN) != 0 &&
-	    (oidp->oid_kind & CTLFLAG_NOFETCH) == 0) {
-		sysctl_load_tunable_by_oid_locked(oidp);
-	}
 }
 
 void
@@ -547,6 +423,8 @@ sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del, int recurse)
 				if (error)
 					return (error);
 			}
+			if (del)
+				free(SYSCTL_CHILDREN(oidp), M_SYSCTLOID);
 		}
 	}
 	if (oidp->oid_refcnt > 1 ) {
@@ -611,16 +489,24 @@ sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
 	}
 	oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
 	oidp->oid_parent = parent;
-	SLIST_INIT(&oidp->oid_children);
+	SLIST_NEXT(oidp, oid_link) = NULL;
 	oidp->oid_number = number;
 	oidp->oid_refcnt = 1;
 	oidp->oid_name = strdup(name, M_SYSCTLOID);
 	oidp->oid_handler = handler;
 	oidp->oid_kind = CTLFLAG_DYN | kind;
-	oidp->oid_arg1 = arg1;
-	oidp->oid_arg2 = arg2;
+	if ((kind & CTLTYPE) == CTLTYPE_NODE) {
+		/* Allocate space for children */
+		SYSCTL_CHILDREN_SET(oidp, malloc(sizeof(struct sysctl_oid_list),
+		    M_SYSCTLOID, M_WAITOK));
+		SLIST_INIT(SYSCTL_CHILDREN(oidp));
+		oidp->oid_arg2 = arg2;
+	} else {
+		oidp->oid_arg1 = arg1;
+		oidp->oid_arg2 = arg2;
+	}
 	oidp->oid_fmt = fmt;
-	if (descr != NULL)
+	if (descr)
 		oidp->oid_descr = strdup(descr, M_SYSCTLOID);
 	/* Update the context, if used */
 	if (clist != NULL)
@@ -691,7 +577,7 @@ sysctl_register_all(void *arg)
 		sysctl_register_oid(*oidp);
 	SYSCTL_XUNLOCK();
 }
-SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_FIRST, sysctl_register_all, 0);
+SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_ANY, sysctl_register_all, 0);
 
 /*
  * "Staff-functions"
@@ -739,7 +625,7 @@ sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
 				printf(" Node\n");
 				if (!oidp->oid_handler) {
 					sysctl_sysctl_debug_dump_node(
-					    SYSCTL_CHILDREN(oidp), i + 2);
+						oidp->oid_arg1, i+2);
 				}
 				break;
 			case CTLTYPE_INT:    printf(" Int\n"); break;
@@ -1207,28 +1093,26 @@ sysctl_handle_64(SYSCTL_HANDLER_ARGS)
 int
 sysctl_handle_string(SYSCTL_HANDLER_ARGS)
 {
+	int error=0;
+	char *tmparg;
 	size_t outlen;
-	int error = 0;
 
-	/* check for zero-length buffer */
-	if (arg2 == 0)
-		return (ENOMEM);
-
-	if (req->oldptr != NULL) {
-		char *tmparg;
-
-		/* try to make a coherent snapshot of the string */
-		tmparg = malloc(arg2, M_SYSCTLTMP, M_WAITOK);
-		memcpy(tmparg, arg1, arg2);
-
-		outlen = strnlen(tmparg, arg2 - 1) + 1;
-		error = SYSCTL_OUT(req, tmparg, outlen);
+	/*
+	 * Attempt to get a coherent snapshot by copying to a
+	 * temporary kernel buffer.
+	 */
+retry:
+	outlen = strlen((char *)arg1)+1;
+	tmparg = malloc(outlen, M_SYSCTLTMP, M_WAITOK);
 
+	if (strlcpy(tmparg, (char *)arg1, outlen) >= outlen) {
 		free(tmparg, M_SYSCTLTMP);
-	} else {
-		outlen = strnlen((char *)arg1, arg2 - 1) + 1;
-		error = SYSCTL_OUT(req, NULL, outlen);
+		goto retry;
 	}
+
+	error = SYSCTL_OUT(req, tmparg, outlen);
+	free(tmparg, M_SYSCTLTMP);
+
 	if (error || !req->newptr)
 		return (error);
 
@@ -1239,6 +1123,7 @@ sysctl_handle_string(SYSCTL_HANDLER_ARGS)
 		error = SYSCTL_IN(req, arg1, arg2);
 		((char *)arg1)[arg2] = '\0';
 	}
+
 	return (error);
 }
 
@@ -1604,14 +1489,24 @@ sysctl_root(SYSCTL_HANDLER_ARGS)
 	if (error != 0)
 		return (error);
 #endif
+	oid->oid_running++;
+	SYSCTL_XUNLOCK();
 #ifdef VIMAGE
 	if ((oid->oid_kind & CTLFLAG_VNET) && arg1 != NULL)
 		arg1 = (void *)(curvnet->vnet_data_base + (uintptr_t)arg1);
 #endif
-	error = sysctl_root_handler_locked(oid, arg1, arg2, req);
+	if (!(oid->oid_kind & CTLFLAG_MPSAFE))
+		mtx_lock(&Giant);
+	error = oid->oid_handler(oid, arg1, arg2, req);
+	if (!(oid->oid_kind & CTLFLAG_MPSAFE))
+		mtx_unlock(&Giant);
 
 	KFAIL_POINT_ERROR(_debug_fail_point, sysctl_running, error);
 
+	SYSCTL_XLOCK();
+	oid->oid_running--;
+	if (oid->oid_running == 0 && (oid->oid_kind & CTLFLAG_DYING) != 0)
+		wakeup(&oid->oid_running);
 	return (error);
 }