Extend the meaning of the CTLFLAG_TUN flag to automatically check if

there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.

Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.

MFC after:	2 weeks
Sponsored by:	Mellanox Technologies

1 files changed, 149 insertions, 44 deletions

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index fec4aea..cb5a266 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -98,10 +98,13 @@ static struct sx sysctlmemlock;
 
 static int sysctl_root(SYSCTL_HANDLER_ARGS);
 
-struct sysctl_oid_list sysctl__children; /* root list */
+/* Root list */
+struct sysctl_oid_list sysctl__children = SLIST_HEAD_INITIALIZER(&sysctl__children);
 
 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)
@@ -136,6 +139,118 @@ 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)
 {
@@ -192,6 +307,15 @@ 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
@@ -423,8 +547,6 @@ 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 ) {
@@ -489,24 +611,16 @@ 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_NEXT(oidp, oid_link) = NULL;
+	SLIST_INIT(&oidp->oid_children);
 	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;
-	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_arg1 = arg1;
+	oidp->oid_arg2 = arg2;
 	oidp->oid_fmt = fmt;
-	if (descr)
+	if (descr != NULL)
 		oidp->oid_descr = strdup(descr, M_SYSCTLOID);
 	/* Update the context, if used */
 	if (clist != NULL)
@@ -577,7 +691,7 @@ sysctl_register_all(void *arg)
 		sysctl_register_oid(*oidp);
 	SYSCTL_XUNLOCK();
 }
-SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_ANY, sysctl_register_all, 0);
+SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_FIRST, sysctl_register_all, 0);
 
 /*
  * "Staff-functions"
@@ -625,7 +739,7 @@ sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
 				printf(" Node\n");
 				if (!oidp->oid_handler) {
 					sysctl_sysctl_debug_dump_node(
-						oidp->oid_arg1, i+2);
+					    SYSCTL_CHILDREN(oidp), i + 2);
 				}
 				break;
 			case CTLTYPE_INT:    printf(" Int\n"); break;
@@ -1093,26 +1207,28 @@ sysctl_handle_64(SYSCTL_HANDLER_ARGS)
 int
 sysctl_handle_string(SYSCTL_HANDLER_ARGS)
 {
-	int error=0;
-	char *tmparg;
 	size_t outlen;
+	int error = 0;
 
-	/*
-	 * 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);
+	/* check for zero-length buffer */
+	if (arg2 == 0)
+		return (ENOMEM);
 
-	if (strlcpy(tmparg, (char *)arg1, outlen) >= outlen) {
-		free(tmparg, M_SYSCTLTMP);
-		goto retry;
-	}
+	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);
 
-	error = SYSCTL_OUT(req, tmparg, outlen);
-	free(tmparg, M_SYSCTLTMP);
+		outlen = strnlen(tmparg, arg2 - 1) + 1;
+		error = SYSCTL_OUT(req, tmparg, outlen);
 
+		free(tmparg, M_SYSCTLTMP);
+	} else {
+		outlen = strnlen((char *)arg1, arg2 - 1) + 1;
+		error = SYSCTL_OUT(req, NULL, outlen);
+	}
 	if (error || !req->newptr)
 		return (error);
 
@@ -1123,7 +1239,6 @@ retry:
 		error = SYSCTL_IN(req, arg1, arg2);
 		((char *)arg1)[arg2] = '\0';
 	}
-
 	return (error);
 }
 
@@ -1489,24 +1604,14 @@ 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
-	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);
+	error = sysctl_root_handler_locked(oid, arg1, arg2, req);
 
 	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);
 }