Remove the garbage collector thread. All resources are freed

in-line. If the exiting thread cannot release a resource, then
the next thread to exit will release it.

7 files changed, 44 insertions, 244 deletions

diff --git a/lib/libthr/thread/Makefile.inc b/lib/libthr/thread/Makefile.inc
index 8e11911..52d428b 100644
--- a/lib/libthr/thread/Makefile.inc
+++ b/lib/libthr/thread/Makefile.inc
@@ -19,7 +19,6 @@ SRCS+= \
 	thr_equal.c \
 	thr_exit.c \
 	thr_find_thread.c \
-	thr_gc.c \
 	thr_getprio.c \
 	thr_info.c \
 	thr_init.c \
diff --git a/lib/libthr/thread/thr_create.c b/lib/libthr/thread/thr_create.c
index 32ca697..5f1887d 100644
--- a/lib/libthr/thread/thr_create.c
+++ b/lib/libthr/thread/thr_create.c
@@ -62,9 +62,7 @@ int
 _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
 	       void *(*start_routine) (void *), void *arg)
 {
-	int		f_gc = 0;
 	int             ret = 0;
-	pthread_t       gc_thread;
 	pthread_t       new_thread;
 	pthread_attr_t	pattr;
 	int		flags;
@@ -148,12 +146,6 @@ _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
 
 	THREAD_LIST_LOCK;
 
-	/*
-	 * Check if the garbage collector thread
-	 * needs to be started.
-	 */
-	f_gc = (TAILQ_FIRST(&_thread_list) == _thread_initial);
-
 	/* Add the thread to the linked list of all threads: */
 	TAILQ_INSERT_HEAD(&_thread_list, new_thread, tle);
 
@@ -180,13 +172,6 @@ _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
 	/* Return a pointer to the thread structure: */
 	(*thread) = new_thread;
 
-	/*
-	 * Start a garbage collector thread
-	 * if necessary.
-	 */
-	if (f_gc && pthread_create(&gc_thread,NULL, _thread_gc,NULL) != 0)
-		PANIC("Can't create gc thread");
-
 	return (0);
 }
 
diff --git a/lib/libthr/thread/thr_exit.c b/lib/libthr/thread/thr_exit.c
index 41b1f86..0455a97 100644
--- a/lib/libthr/thread/thr_exit.c
+++ b/lib/libthr/thread/thr_exit.c
@@ -45,6 +45,8 @@ __weak_reference(_pthread_exit, pthread_exit);
 /* thr_exit() */
 extern int _thr_exit(void);
 
+static void	deadlist_free_threads();
+
 void
 _thread_exit(char *fname, int lineno, char *string)
 {
@@ -171,9 +173,11 @@ retry:
 	}
 
 	/*
+	 * Free any memory allocated for dead threads.
 	 * Add this thread to the list of dead threads, and
 	 * also remove it from the active threads list.
 	 */
+	deadlist_free_threads();
 	TAILQ_INSERT_HEAD(&_dead_list, curthread, dle);
 	TAILQ_REMOVE(&_thread_list, curthread, tle);
 	PTHREAD_SET_STATE(curthread, PS_DEAD);
@@ -184,20 +188,11 @@ retry:
 		exitNow = 1;
 
 	THREAD_LIST_UNLOCK;
-
-	/*
-	 * Signal the garbage collector thread that there is something
-	 * to clean up. But don't allow it to free the memory until after
-	 * it is retired by holding on to the dead list lock.
-	 */
-	if (pthread_cond_signal(&_gc_cond) != 0)
-		PANIC("Cannot signal gc cond");
+	DEAD_LIST_UNLOCK;
 
 	if (exitNow)
 		exit(0);
 
-	DEAD_LIST_UNLOCK;
-
 	/*
 	 * This function will not return unless we are the last
 	 * thread, which we can't be because we've already checked
@@ -208,3 +203,36 @@ retry:
 	/* This point should not be reached. */
 	PANIC("Dead thread has resumed");
 }
+
+/*
+ * Note: this function must be called with the dead thread list
+ *	 locked.
+ */
+static void
+deadlist_free_threads()
+{
+	struct pthread *ptd, *ptdTemp;
+
+	TAILQ_FOREACH_SAFE(ptd, &_dead_list, dle, ptdTemp) {
+		/* Don't destroy the initial thread or non-detached threads. */
+		if (ptd == _thread_initial ||
+		    (ptd->attr.flags & PTHREAD_DETACHED) == 0)
+			continue;
+		TAILQ_REMOVE(&_dead_list, ptd, dle);
+		deadlist_free_onethread(ptd);
+	}
+}
+
+void
+deadlist_free_onethread(struct pthread *ptd)
+{
+
+	if (ptd->attr.stackaddr_attr == NULL && ptd->stack != NULL) {
+		STACK_LOCK;
+		_thread_stack_free(ptd->stack, ptd->attr.stacksize_attr,
+		    ptd->attr.guardsize_attr);
+		STACK_UNLOCK;
+	}
+	_retire_thread(ptd->arch_id);
+	free(ptd);
+}
diff --git a/lib/libthr/thread/thr_gc.c b/lib/libthr/thread/thr_gc.c
deleted file mode 100644
index 1f6bc6b..0000000
--- a/lib/libthr/thread/thr_gc.c
+++ /dev/null
@@ -1,203 +0,0 @@
-/*
- * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *	This product includes software developed by John Birrell.
- * 4. Neither the name of the author nor the names of any co-contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * $FreeBSD$
- *
- * Garbage collector thread. Frees memory allocated for dead threads.
- *
- */
-#include <sys/param.h>
-#include <errno.h>
-#include <time.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include <pthread.h>
-#include "thr_private.h"
-
-pthread_addr_t
-_thread_gc(pthread_addr_t arg)
-{
-	int		f_debug;
-	int		f_done = 0;
-	int		ret;
-	sigset_t	mask;
-	pthread_t	pthread;
-	pthread_t	pthread_cln;
-	struct timespec	abstime;
-	void		*p_stack;
-
-	/* Block all signals */
-	sigfillset(&mask);
-	pthread_sigmask(SIG_BLOCK, &mask, NULL);
-
-	/* Mark this thread as a library thread (not a user thread). */
-	curthread->flags |= PTHREAD_FLAGS_PRIVATE;
-
-	/* Set a debug flag based on an environment variable. */
-	f_debug = (getenv("LIBC_R_DEBUG") != NULL);
-
-	/* Set the name of this thread. */
-	pthread_set_name_np(curthread,"GC");
-
-	while (!f_done) {
-		/* Check if debugging this application. */
-		if (f_debug)
-			/* Dump thread info to file. */
-			_thread_dump_info();
-
-		/*
-		 * Lock the list of dead threads which ensures that
-		 * this thread sees another thread exit:
-		 */
-		DEAD_LIST_LOCK;
-
-		/* No stack or thread structure to free yet. */
-		p_stack = NULL;
-		pthread_cln = NULL;
-
-		/* Check if this is the last running thread. */
-		THREAD_LIST_LOCK;
-		if (TAILQ_FIRST(&_thread_list) == curthread &&
-		    TAILQ_NEXT(curthread, tle) == NULL)
-			/*
-			 * This is the last thread, so it can exit
-			 * now.
-			 */
-			f_done = 1;
-		THREAD_LIST_UNLOCK;
-
-		/*
-		 * Enter a loop to search for the first dead thread that
-		 * has memory to free.
-		 */
-		for (pthread = TAILQ_FIRST(&_dead_list);
-		     p_stack == NULL && pthread_cln == NULL && pthread != NULL;
-		     pthread = TAILQ_NEXT(pthread, dle)) {
-			/* Don't destroy the initial thread. */
-			if (pthread == _thread_initial) 
-				continue;
-
-			UMTX_LOCK(&pthread->lock);
-
-			/*
-			 * Check if the stack was not specified by
-			 * the caller to pthread_create() and has not
-			 * been destroyed yet: 
-			 */
-			STACK_LOCK;
-			if (pthread->attr.stackaddr_attr == NULL &&
-			    pthread->stack != NULL) {
-				_thread_stack_free(pthread->stack,
-				    pthread->attr.stacksize_attr,
-				    pthread->attr.guardsize_attr);
-				pthread->stack = NULL;
-			}
-			STACK_UNLOCK;
-
-			/*
-			 * If the thread has not been detached, leave
-			 * it on the dead thread list.
-			 */
-			if ((pthread->attr.flags & PTHREAD_DETACHED) == 0) {
-				UMTX_UNLOCK(&pthread->lock);
-				continue;
-			}
-
-			/* Remove this thread from the dead list: */
-			TAILQ_REMOVE(&_dead_list, pthread, dle);
-
-			/*
-			 * Point to the thread structure that must
-			 * be freed outside the locks:
-			 */
-			pthread_cln = pthread;
-
-			UMTX_UNLOCK(&pthread->lock);
-
-			/*
-		 	 * Retire the architecture specific id so it may be
-		 	 * used for new threads.
-			 */
-			_retire_thread(pthread_cln->arch_id);
-
-		}
-
-		/*
-		 * Check if this is not the last thread and there is no
-		 * memory to free this time around.
-		 */
-		if (!f_done && p_stack == NULL && pthread_cln == NULL) {
-			/* Get the current time. */
-			if (clock_gettime(CLOCK_REALTIME,&abstime) != 0)
-				PANIC("gc cannot get time");
-
-			/*
-			 * Do a backup poll in 10 seconds if no threads
-			 * die before then.
-			 */
-			abstime.tv_sec += 10;
-
-			/*
-			 * Wait for a signal from a dying thread or a
-			 * timeout (for a backup poll).
-			 */
-			if ((ret = pthread_cond_timedwait(&_gc_cond,
-			    &dead_list_lock, &abstime)) != 0 && ret != ETIMEDOUT) {
-				_thread_printf(STDERR_FILENO, "ret = %d", ret);
-				PANIC("gc cannot wait for a signal");
-			}
-		}
-
-		/* Unlock the garbage collector mutex: */
-		DEAD_LIST_UNLOCK;
-
-		/*
-		 * If there is memory to free, do it now. The call to
-		 * free() might block, so this must be done outside the
-		 * locks.
-		 */
-		if (p_stack != NULL)
-			free(p_stack);
-		if (pthread_cln != NULL) {
-			if (pthread_cln->name != NULL) {
-				/* Free the thread name string. */
-				free(pthread_cln->name);
-			}
-			/*
-			 * Free the memory allocated for the thread
-			 * structure.
-			 */
-			free(pthread_cln);
-		}
-	}
-	return (NULL);
-}
diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c
index 68532f1..d74ed2d 100644
--- a/lib/libthr/thread/thr_init.c
+++ b/lib/libthr/thread/thr_init.c
@@ -224,7 +224,6 @@ init_tdlist(struct pthread *td, int reinit)
 			}
 		}
 		_pthread_mutex_destroy(&dead_list_lock);
-		_pthread_cond_destroy(&_gc_cond);
 	} else {
 		TAILQ_INIT(&_thread_list);
 		TAILQ_INIT(&_dead_list);
@@ -235,11 +234,10 @@ init_tdlist(struct pthread *td, int reinit)
 
 	/*
 	 * Initialize the active thread list lock and the
-	 * dead threads list lock & associated condition variable.
+	 * dead threads list lock.
 	 */
 	memset(&thread_list_lock, 0, sizeof(spinlock_t));
-	if (_pthread_mutex_init(&dead_list_lock,NULL) != 0 ||
-	    _pthread_cond_init(&_gc_cond,NULL) != 0)
+	if (_pthread_mutex_init(&dead_list_lock,NULL) != 0)
 		PANIC("Failed to initialize garbage collector primitives");
 }
 
diff --git a/lib/libthr/thread/thr_join.c b/lib/libthr/thread/thr_join.c
index 30acc93..b96eedc 100644
--- a/lib/libthr/thread/thr_join.c
+++ b/lib/libthr/thread/thr_join.c
@@ -160,12 +160,12 @@ _pthread_join(pthread_t pthread, void **thread_return)
 			*thread_return = pthread->ret;
 		}
 
-		/* Make the thread collectable by the garbage collector. */
+		/* Free all remaining memory allocated to the thread. */
 		pthread->attr.flags |= PTHREAD_DETACHED;
 		UMTX_UNLOCK(&pthread->lock);
+		TAILQ_REMOVE(&_dead_list, pthread, dle);
+		deadlist_free_onethread(pthread);
 		THREAD_LIST_UNLOCK;
-		if (pthread_cond_signal(&_gc_cond) != 0)
-			PANIC("Cannot signal gc cond");
 		DEAD_LIST_UNLOCK;
 	}
 
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index 081a0eb..901c26f 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -719,13 +719,6 @@ SCLASS int    _clock_res_usec		/* Clock resolution in usec.	*/
 ;
 #endif
 
-/* Garbage collector condition variable. */
-SCLASS	pthread_cond_t  _gc_cond
-#ifdef GLOBAL_PTHREAD_PRIVATE
-= NULL
-#endif
-;
-
 /*
  * Array of signal actions for this process.
  */
@@ -791,7 +784,6 @@ void	_thread_sig_wrapper(int sig, siginfo_t *info, void *context);
 void	_thread_printf(int fd, const char *, ...);
 void    _thread_start(void);
 void	_thread_seterrno(pthread_t, int);
-pthread_addr_t _thread_gc(pthread_addr_t);
 void	_thread_enter_cancellation_point(void);
 void	_thread_leave_cancellation_point(void);
 void	_thread_cancellation_point(void);
@@ -802,6 +794,7 @@ void	_thread_sigblock();
 void	_thread_sigunblock();
 void	adjust_prio_inheritance(struct pthread *);
 void	adjust_prio_protection(struct pthread *);
+void	deadlist_free_onethread(struct pthread *);
 void	init_td_common(struct pthread *, struct pthread_attr *, int);
 void	init_tdlist(struct pthread *, int);
 void	proc_sigact_copyin(int, const struct sigaction *);