Revamp the mechanism for enumerating and calling shared objects'

init and fini functions.  Now the code is very careful to hold no
locks when calling these functions.  Thus the dynamic linker cannot
be re-entered with a lock already held.

Remove the tolerance for recursive locking that I added in revision
1.2 of dllockinit.c.  Recursive locking shouldn't happen any more.

Mozilla and JDK users: I'd appreciate confirmation that things still
work right (or at least the same) with these changes.

6 files changed, 187 insertions, 139 deletions

diff --git a/libexec/rtld-elf/alpha/lockdflt.c b/libexec/rtld-elf/alpha/lockdflt.c
index c92695001bd7..f9dbc5d66a3f 100644
--- a/libexec/rtld-elf/alpha/lockdflt.c
+++ b/libexec/rtld-elf/alpha/lockdflt.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright 1999 John D. Polstra.
+ * Copyright 1999, 2000 John D. Polstra.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -51,11 +51,8 @@ void
 lockdflt_acquire(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
-    sigset_t old_mask;
-
-    sigprocmask(SIG_BLOCK, &l->lock_mask, &old_mask);
-    if (l->depth == 0)
-	l->old_mask = old_mask;
+    sigprocmask(SIG_BLOCK, &l->lock_mask, &l->old_mask);
+    assert(l->depth == 0);
     l->depth++;
 }
 
@@ -84,15 +81,7 @@ void
 lockdflt_release(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
+    assert(l->depth == 1);
     l->depth--;
-    assert(l->depth >= 0);
-    if (l->depth == 0)
-	sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
-}
-
-void
-lockdflt_init(void)
-{
-    dllockinit(NULL, lockdflt_create, lockdflt_acquire, lockdflt_acquire,
-      lockdflt_release, lockdflt_destroy, NULL);
+    sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
 }
diff --git a/libexec/rtld-elf/amd64/lockdflt.c b/libexec/rtld-elf/amd64/lockdflt.c
index c92695001bd7..f9dbc5d66a3f 100644
--- a/libexec/rtld-elf/amd64/lockdflt.c
+++ b/libexec/rtld-elf/amd64/lockdflt.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright 1999 John D. Polstra.
+ * Copyright 1999, 2000 John D. Polstra.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -51,11 +51,8 @@ void
 lockdflt_acquire(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
-    sigset_t old_mask;
-
-    sigprocmask(SIG_BLOCK, &l->lock_mask, &old_mask);
-    if (l->depth == 0)
-	l->old_mask = old_mask;
+    sigprocmask(SIG_BLOCK, &l->lock_mask, &l->old_mask);
+    assert(l->depth == 0);
     l->depth++;
 }
 
@@ -84,15 +81,7 @@ void
 lockdflt_release(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
+    assert(l->depth == 1);
     l->depth--;
-    assert(l->depth >= 0);
-    if (l->depth == 0)
-	sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
-}
-
-void
-lockdflt_init(void)
-{
-    dllockinit(NULL, lockdflt_create, lockdflt_acquire, lockdflt_acquire,
-      lockdflt_release, lockdflt_destroy, NULL);
+    sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
 }
diff --git a/libexec/rtld-elf/i386/lockdflt.c b/libexec/rtld-elf/i386/lockdflt.c
index c92695001bd7..f9dbc5d66a3f 100644
--- a/libexec/rtld-elf/i386/lockdflt.c
+++ b/libexec/rtld-elf/i386/lockdflt.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright 1999 John D. Polstra.
+ * Copyright 1999, 2000 John D. Polstra.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -51,11 +51,8 @@ void
 lockdflt_acquire(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
-    sigset_t old_mask;
-
-    sigprocmask(SIG_BLOCK, &l->lock_mask, &old_mask);
-    if (l->depth == 0)
-	l->old_mask = old_mask;
+    sigprocmask(SIG_BLOCK, &l->lock_mask, &l->old_mask);
+    assert(l->depth == 0);
     l->depth++;
 }
 
@@ -84,15 +81,7 @@ void
 lockdflt_release(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
+    assert(l->depth == 1);
     l->depth--;
-    assert(l->depth >= 0);
-    if (l->depth == 0)
-	sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
-}
-
-void
-lockdflt_init(void)
-{
-    dllockinit(NULL, lockdflt_create, lockdflt_acquire, lockdflt_acquire,
-      lockdflt_release, lockdflt_destroy, NULL);
+    sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
 }
diff --git a/libexec/rtld-elf/lockdflt.c b/libexec/rtld-elf/lockdflt.c
index c92695001bd7..f9dbc5d66a3f 100644
--- a/libexec/rtld-elf/lockdflt.c
+++ b/libexec/rtld-elf/lockdflt.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright 1999 John D. Polstra.
+ * Copyright 1999, 2000 John D. Polstra.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -51,11 +51,8 @@ void
 lockdflt_acquire(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
-    sigset_t old_mask;
-
-    sigprocmask(SIG_BLOCK, &l->lock_mask, &old_mask);
-    if (l->depth == 0)
-	l->old_mask = old_mask;
+    sigprocmask(SIG_BLOCK, &l->lock_mask, &l->old_mask);
+    assert(l->depth == 0);
     l->depth++;
 }
 
@@ -84,15 +81,7 @@ void
 lockdflt_release(void *lock)
 {
     LockDflt *l = (LockDflt *)lock;
+    assert(l->depth == 1);
     l->depth--;
-    assert(l->depth >= 0);
-    if (l->depth == 0)
-	sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
-}
-
-void
-lockdflt_init(void)
-{
-    dllockinit(NULL, lockdflt_create, lockdflt_acquire, lockdflt_acquire,
-      lockdflt_release, lockdflt_destroy, NULL);
+    sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
 }
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 5bcd390a6232..b5bba084544d 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright 1996, 1997, 1998, 1999 John D. Polstra.
+ * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -73,13 +73,16 @@ typedef struct Struct_LockInfo {
  * Function declarations.
  */
 static const char *basename(const char *);
-static void call_fini_functions(Obj_Entry *);
-static void call_init_functions(Obj_Entry *);
 static void die(void);
 static void digest_dynamic(Obj_Entry *);
 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
 static Obj_Entry *dlcheck(void *);
 static char *find_library(const char *, const Obj_Entry *);
+static void funclist_call(Funclist *);
+static void funclist_clear(Funclist *);
+static void funclist_init(Funclist *);
+static void funclist_push_head(Funclist *, InitFunc);
+static void funclist_push_tail(Funclist *, InitFunc);
 static const char *gethints(void);
 static void init_dag(Obj_Entry *);
 static void init_dag1(Obj_Entry *root, Obj_Entry *obj);
@@ -102,7 +105,7 @@ static void set_program_var(const char *, const void *);
 static const Elf_Sym *symlook_list(const char *, unsigned long,
   Objlist *, const Obj_Entry **, bool in_plt);
 static void trace_loaded_objects(Obj_Entry *obj);
-static void unload_object(Obj_Entry *, bool do_fini_funcs);
+static void unload_object(Obj_Entry *);
 static void unref_dag(Obj_Entry *);
 
 void r_debug_state(void);
@@ -158,7 +161,7 @@ static func_ptr_type exports[] = {
 
 /*
  * Global declarations normally provided by crt1.  The dynamic linker is
- * not build with crt1, so we have to provide them ourselves.
+ * not built with crt1, so we have to provide them ourselves.
  */
 char *__progname;
 char **environ;
@@ -209,6 +212,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
     Elf_Auxinfo *auxp;
     const char *argv0;
     Obj_Entry *obj;
+    Funclist initlist;
 
     /*
      * On entry, the dynamic linker itself has not been relocated yet.
@@ -325,15 +329,22 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
     if (load_needed_objects(obj_main) == -1)
 	die();
 
-    for (obj = obj_list;  obj != NULL;  obj = obj->next)
+    /*
+     * Make a list of all objects loaded at startup.  Also construct
+     * the list of init functions to call, in reverse order.
+     */
+    funclist_init(&initlist);
+    for (obj = obj_list;  obj != NULL;  obj = obj->next) {
 	objlist_add(&list_main, obj);
+	if (obj->init != NULL && !obj->mainprog)
+	    funclist_push_head(&initlist, obj->init);
+    }
 
     if (ld_tracing) {		/* We're done */
 	trace_loaded_objects(obj_main);
 	exit(0);
     }
 
-    dbg("relocating objects");
     if (relocate_objects(obj_main,
 	ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
 	die();
@@ -351,8 +362,10 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
 
     r_debug_state();		/* say hello to gdb! */
 
-    dbg("calling _init functions");
-    call_init_functions(obj_main->next);
+    funclist_call(&initlist);
+    wlock_acquire();
+    funclist_clear(&initlist);
+    lock_release();
 
     dbg("transferring control to program entry point = %p", obj_main->entry);
 
@@ -418,26 +431,6 @@ basename(const char *name)
 }
 
 static void
-call_fini_functions(Obj_Entry *first)
-{
-    Obj_Entry *obj;
-
-    for (obj = first;  obj != NULL;  obj = obj->next)
-	if (obj->fini != NULL)
-	    (*obj->fini)();
-}
-
-static void
-call_init_functions(Obj_Entry *first)
-{
-    if (first != NULL) {
-	call_init_functions(first->next);
-	if (first->init != NULL)
-	    (*first->init)();
-    }
-}
-
-static void
 die(void)
 {
     const char *msg = dlerror();
@@ -565,11 +558,11 @@ digest_dynamic(Obj_Entry *obj)
 	    break;
 
 	case DT_INIT:
-	    obj->init = (void (*)(void)) (obj->relocbase + dynp->d_un.d_ptr);
+	    obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
 	    break;
 
 	case DT_FINI:
-	    obj->fini = (void (*)(void)) (obj->relocbase + dynp->d_un.d_ptr);
+	    obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
 	    break;
 
 	case DT_DEBUG:
@@ -834,6 +827,55 @@ find_symdef(unsigned long symnum, Obj_Entry *refobj,
     return def;
 }
 
+static void
+funclist_call(Funclist *list)
+{
+    Funclist_Entry *elm;
+
+    STAILQ_FOREACH(elm, list, link) {
+	dbg("calling init/fini function at %p", elm->func);
+	(*elm->func)();
+    }
+}
+
+static void
+funclist_clear(Funclist *list)
+{
+    Funclist_Entry *elm;
+
+    while (!STAILQ_EMPTY(list)) {
+	elm = STAILQ_FIRST(list);
+	STAILQ_REMOVE_HEAD(list, link);
+	free(elm);
+    }
+}
+
+static void
+funclist_init(Funclist *list)
+{
+    STAILQ_INIT(list);
+}
+
+static void
+funclist_push_head(Funclist *list, InitFunc func)
+{
+    Funclist_Entry *elm;
+
+    elm = NEW(Funclist_Entry);
+    elm->func = func;
+    STAILQ_INSERT_HEAD(list, elm, link);
+}
+
+static void
+funclist_push_tail(Funclist *list, InitFunc func)
+{
+    Funclist_Entry *elm;
+
+    elm = NEW(Funclist_Entry);
+    elm->func = func;
+    STAILQ_INSERT_TAIL(list, elm, link);
+}
+
 /*
  * Return the search path from the ldconfig hints file, reading it if
  * necessary.  Returns NULL if there are problems with the hints file,
@@ -1214,8 +1256,12 @@ relocate_objects(Obj_Entry *first, bool bind_now)
 static void
 rtld_exit(void)
 {
+    Obj_Entry *obj;
+
     dbg("rtld_exit()");
-    call_fini_functions(obj_list->next);
+    for (obj = obj_list->next;  obj != NULL;  obj = obj->next)
+	if (obj->fini != NULL)
+	    (*obj->fini)();
 }
 
 static char *
@@ -1258,6 +1304,8 @@ int
 dlclose(void *handle)
 {
     Obj_Entry *root;
+    Obj_Entry *obj;
+    Funclist finilist;
 
     wlock_acquire();
     root = dlcheck(handle);
@@ -1266,11 +1314,31 @@ dlclose(void *handle)
 	return -1;
     }
 
-    GDB_STATE(RT_DELETE);
-    unload_object(root, true);
+    /* Unreference the object and its dependencies. */
     root->dl_refcount--;
-    GDB_STATE(RT_CONSISTENT);
+    unref_dag(root);
 
+    if (root->refcount == 0) {
+	/*
+	 * The object is no longer referenced, so we must unload it.
+	 * First, make a list of the fini functions and then call them
+	 * with no locks held.
+	 */
+	funclist_init(&finilist);
+	for (obj = obj_list->next;  obj != NULL;  obj = obj->next)
+	    if (obj->refcount == 0 && obj->fini != NULL)
+		funclist_push_tail(&finilist, obj->fini);
+
+	lock_release();
+	funclist_call(&finilist);
+	wlock_acquire();
+	funclist_clear(&finilist);
+
+	/* Finish cleaning up the newly-unreferenced objects. */
+	GDB_STATE(RT_DELETE);
+	unload_object(root);
+	GDB_STATE(RT_CONSISTENT);
+    }
     lock_release();
     return 0;
 }
@@ -1338,6 +1406,10 @@ dlopen(const char *name, int mode)
 {
     Obj_Entry **old_obj_tail;
     Obj_Entry *obj;
+    Obj_Entry *initobj;
+    Funclist initlist;
+
+    funclist_init(&initlist);
 
     wlock_acquire();
     GDB_STATE(RT_ADD);
@@ -1363,15 +1435,27 @@ dlopen(const char *name, int mode)
 
 	    if (load_needed_objects(obj) == -1 ||
 	      (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
-		unload_object(obj, false);
 		obj->dl_refcount--;
+		unref_dag(obj);
+		if (obj->refcount == 0)
+		    unload_object(obj);
 		obj = NULL;
-	    } else
-		call_init_functions(obj);
+	    } else {
+		/* Make list of init functions to call, in reverse order */
+		for (initobj = obj; initobj != NULL; initobj = initobj->next)
+		    if (initobj->init != NULL)
+			funclist_push_head(&initlist, initobj->init);
+	    }
 	}
     }
 
     GDB_STATE(RT_CONSISTENT);
+
+    /* Call the init functions with no locks held. */
+    lock_release();
+    funclist_call(&initlist);
+    wlock_acquire();
+    funclist_clear(&initlist);
     lock_release();
     return obj;
 }
@@ -1734,44 +1818,40 @@ trace_loaded_objects(Obj_Entry *obj)
 }
 
 /*
- * Note, this is called only for objects loaded by dlopen().
+ * Unload a dlopened object and its dependencies from memory and from
+ * our data structures.  It is assumed that the DAG rooted in the
+ * object has already been unreferenced, and that the object has a
+ * reference count of 0.
  */
 static void
-unload_object(Obj_Entry *root, bool do_fini_funcs)
+unload_object(Obj_Entry *root)
 {
-    unref_dag(root);
-    if (root->refcount == 0) {	/* We are finished with some objects. */
-	Obj_Entry *obj;
-	Obj_Entry **linkp;
-	Objlist_Entry *elm;
-
-	/* Finalize objects that are about to be unmapped. */
-	if (do_fini_funcs)
-	    for (obj = obj_list->next;  obj != NULL;  obj = obj->next)
-		if (obj->refcount == 0 && obj->fini != NULL)
-		    (*obj->fini)();
-
-	/* Remove the DAG from all objects' DAG lists. */
-	STAILQ_FOREACH(elm, &root->dagmembers , link)
-	    objlist_remove(&elm->obj->dldags, root);
-
-	/* Remove the DAG from the RTLD_GLOBAL list. */
-	objlist_remove(&list_global, root);
-
-	/* Unmap all objects that are no longer referenced. */
-	linkp = &obj_list->next;
-	while ((obj = *linkp) != NULL) {
-	    if (obj->refcount == 0) {
-		dbg("unloading \"%s\"", obj->path);
-		munmap(obj->mapbase, obj->mapsize);
-		linkmap_delete(obj);
-		*linkp = obj->next;
-		obj_free(obj);
-	    } else
-		linkp = &obj->next;
-	}
-	obj_tail = linkp;
+    Obj_Entry *obj;
+    Obj_Entry **linkp;
+    Objlist_Entry *elm;
+
+    assert(root->refcount == 0);
+
+    /* Remove the DAG from all objects' DAG lists. */
+    STAILQ_FOREACH(elm, &root->dagmembers , link)
+	objlist_remove(&elm->obj->dldags, root);
+
+    /* Remove the DAG from the RTLD_GLOBAL list. */
+    objlist_remove(&list_global, root);
+
+    /* Unmap all objects that are no longer referenced. */
+    linkp = &obj_list->next;
+    while ((obj = *linkp) != NULL) {
+	if (obj->refcount == 0) {
+	    dbg("unloading \"%s\"", obj->path);
+	    munmap(obj->mapbase, obj->mapsize);
+	    linkmap_delete(obj);
+	    *linkp = obj->next;
+	    obj_free(obj);
+	} else
+	    linkp = &obj->next;
     }
+    obj_tail = linkp;
 }
 
 static void
diff --git a/libexec/rtld-elf/rtld.h b/libexec/rtld-elf/rtld.h
index b8fcf2c78fb2..3a88547d0298 100644
--- a/libexec/rtld-elf/rtld.h
+++ b/libexec/rtld-elf/rtld.h
@@ -1,5 +1,5 @@
 /*-
- * Copyright 1996-1998 John D. Polstra.
+ * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -52,6 +52,7 @@ typedef unsigned char bool;
 struct stat;
 struct Struct_Obj_Entry;
 
+/* Lists of shared objects */
 typedef struct Struct_Objlist_Entry {
     STAILQ_ENTRY(Struct_Objlist_Entry) link;
     struct Struct_Obj_Entry *obj;
@@ -59,6 +60,17 @@ typedef struct Struct_Objlist_Entry {
 
 typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
 
+/* Lists of init or fini functions */
+typedef void (*InitFunc)(void);
+
+typedef struct Struct_Funclist_Entry {
+    STAILQ_ENTRY(Struct_Funclist_Entry) link;
+    InitFunc func;
+} Funclist_Entry;
+
+typedef STAILQ_HEAD(Struct_Funclist, Struct_Funclist_Entry) Funclist;
+
+/* Lists of shared object dependencies */
 typedef struct Struct_Needed_Entry {
     struct Struct_Needed_Entry *next;
     struct Struct_Obj_Entry *obj;
@@ -122,8 +134,8 @@ typedef struct Struct_Obj_Entry {
     const char *rpath;		/* Search path specified in object */
     Needed_Entry *needed;	/* Shared objects needed by this one (%) */
 
-    void (*init)(void);		/* Initialization function to call */
-    void (*fini)(void);		/* Termination function to call */
+    InitFunc init;		/* Initialization function to call */
+    InitFunc fini;		/* Termination function to call */
 
     bool mainprog;		/* True if this is the main program */
     bool rtld;			/* True if this is the dynamic linker */