71d09bc86a
list is protected by a spinlock_t, but the dead list uses a pthread_mutex because it is necessary to synchronize other threads with the garbage collector thread. Lock/Unlock macros are used so it's easier to make changes to the locks in the future. The 'dead thread list' lock is intended to replace the gc mutex. This doesn't have any practical ramifications. It simply makes it clearer what the purpose of the lock is. The gc will use this lock, instead of the gc mutex, to synchronize access to the dead list with other threads. Modify _pthread_exit() to use these two new locks instead of GIANT_LOCK, and also to properly lock and protect thread state changes, especially with respect to a joining thread. The gc thread was also re-arranged to be more organized and less nested. _pthread_join() was also modified to use the thread list locks. However, locking and unlocking here needs special care because a thread could find itself in a position where it's joining an exiting thread that is waiting on the dead list lock, which this thread (joiner) holds. If the joiner doesn't take care to lock *and* unlock in the same order they (the joiner and the joinee) could deadlock against each other. Approved by: re/blanket libthr
237 lines
8.5 KiB
C
237 lines
8.5 KiB
C
/*
|
|
* Copyright (c) 2001 Daniel Eischen <deischen@freebsd.org>
|
|
* Copyright (c) 2000-2001 Jason Evans <jasone@freebsd.org>
|
|
* 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.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
#include <sys/types.h>
|
|
#include <sys/mman.h>
|
|
#include <sys/param.h>
|
|
#include <sys/queue.h>
|
|
#include <sys/user.h>
|
|
#include <stdlib.h>
|
|
#include <pthread.h>
|
|
#include "thr_private.h"
|
|
|
|
/* Spare thread stack. */
|
|
struct stack {
|
|
LIST_ENTRY(stack) qe; /* Stack queue linkage. */
|
|
size_t stacksize; /* Stack size (rounded up). */
|
|
size_t guardsize; /* Guard size. */
|
|
void *stackaddr; /* Stack address. */
|
|
};
|
|
|
|
/*
|
|
* Default sized (stack and guard) spare stack queue. Stacks are cached to
|
|
* avoid additional complexity managing mmap()ed stack regions. Spare stacks
|
|
* are used in LIFO order to increase cache locality.
|
|
*/
|
|
static LIST_HEAD(, stack) _dstackq = LIST_HEAD_INITIALIZER(_dstackq);
|
|
|
|
/*
|
|
* Miscellaneous sized (non-default stack and/or guard) spare stack queue.
|
|
* Stacks are cached to avoid additional complexity managing mmap()ed stack
|
|
* regions. This list is unordered, since ordering on both stack size and guard
|
|
* size would be more trouble than it's worth. Stacks are allocated from this
|
|
* cache on a first size match basis.
|
|
*/
|
|
static LIST_HEAD(, stack) _mstackq = LIST_HEAD_INITIALIZER(_mstackq);
|
|
|
|
/**
|
|
* Base address of the last stack allocated (including its red zone, if there is
|
|
* one). Stacks are allocated contiguously, starting beyond the top of the main
|
|
* stack. When a new stack is created, a red zone is typically created
|
|
* (actually, the red zone is simply left unmapped) above the top of the stack,
|
|
* such that the stack will not be able to grow all the way to the bottom of the
|
|
* next stack. This isn't fool-proof. It is possible for a stack to grow by a
|
|
* large amount, such that it grows into the next stack, and as long as the
|
|
* memory within the red zone is never accessed, nothing will prevent one thread
|
|
* stack from trouncing all over the next.
|
|
*
|
|
* low memory
|
|
* . . . . . . . . . . . . . . . . . .
|
|
* | |
|
|
* | stack 3 | start of 3rd thread stack
|
|
* +-----------------------------------+
|
|
* | |
|
|
* | Red Zone (guard page) | red zone for 2nd thread
|
|
* | |
|
|
* +-----------------------------------+
|
|
* | stack 2 - PTHREAD_STACK_DEFAULT | top of 2nd thread stack
|
|
* | |
|
|
* | |
|
|
* | |
|
|
* | |
|
|
* | stack 2 |
|
|
* +-----------------------------------+ <-- start of 2nd thread stack
|
|
* | |
|
|
* | Red Zone | red zone for 1st thread
|
|
* | |
|
|
* +-----------------------------------+
|
|
* | stack 1 - PTHREAD_STACK_DEFAULT | top of 1st thread stack
|
|
* | |
|
|
* | |
|
|
* | |
|
|
* | |
|
|
* | stack 1 |
|
|
* +-----------------------------------+ <-- start of 1st thread stack
|
|
* | | (initial value of last_stack)
|
|
* | Red Zone |
|
|
* | | red zone for main thread
|
|
* +-----------------------------------+
|
|
* | USRSTACK - PTHREAD_STACK_INITIAL | top of main thread stack
|
|
* | | ^
|
|
* | | |
|
|
* | | |
|
|
* | | | stack growth
|
|
* | |
|
|
* +-----------------------------------+ <-- start of main thread stack
|
|
* (USRSTACK)
|
|
* high memory
|
|
*
|
|
*/
|
|
static void * last_stack;
|
|
|
|
void *
|
|
_thread_stack_alloc(size_t stacksize, size_t guardsize)
|
|
{
|
|
void *stack = NULL;
|
|
struct stack *spare_stack;
|
|
size_t stack_size;
|
|
|
|
/*
|
|
* Round up stack size to nearest multiple of _pthread_page_size,
|
|
* so that mmap() * will work. If the stack size is not an even
|
|
* multiple, we end up initializing things such that there is unused
|
|
* space above the beginning of the stack, so the stack sits snugly
|
|
* against its guard.
|
|
*/
|
|
if (stacksize % _pthread_page_size != 0)
|
|
stack_size = ((stacksize / _pthread_page_size) + 1) *
|
|
_pthread_page_size;
|
|
else
|
|
stack_size = stacksize;
|
|
|
|
/*
|
|
* If the stack and guard sizes are default, try to allocate a stack
|
|
* from the default-size stack cache:
|
|
*/
|
|
if (stack_size == PTHREAD_STACK_DEFAULT &&
|
|
guardsize == _pthread_guard_default) {
|
|
/*
|
|
* Use the garbage collector mutex for synchronization of the
|
|
* spare stack list.
|
|
*/
|
|
DEAD_LIST_LOCK;
|
|
|
|
if ((spare_stack = LIST_FIRST(&_dstackq)) != NULL) {
|
|
/* Use the spare stack. */
|
|
LIST_REMOVE(spare_stack, qe);
|
|
stack = spare_stack->stackaddr;
|
|
}
|
|
|
|
/* Unlock the garbage collector mutex. */
|
|
DEAD_LIST_UNLOCK;
|
|
}
|
|
/*
|
|
* The user specified a non-default stack and/or guard size, so try to
|
|
* allocate a stack from the non-default size stack cache, using the
|
|
* rounded up stack size (stack_size) in the search:
|
|
*/
|
|
else {
|
|
/*
|
|
* Use the garbage collector mutex for synchronization of the
|
|
* spare stack list.
|
|
*/
|
|
DEAD_LIST_LOCK;
|
|
|
|
LIST_FOREACH(spare_stack, &_mstackq, qe) {
|
|
if (spare_stack->stacksize == stack_size &&
|
|
spare_stack->guardsize == guardsize) {
|
|
LIST_REMOVE(spare_stack, qe);
|
|
stack = spare_stack->stackaddr;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Unlock the garbage collector mutex. */
|
|
DEAD_LIST_UNLOCK;
|
|
}
|
|
|
|
/* Check if a stack was not allocated from a stack cache: */
|
|
if (stack == NULL) {
|
|
|
|
if (last_stack == NULL)
|
|
last_stack = _usrstack - PTHREAD_STACK_INITIAL -
|
|
_pthread_guard_default;
|
|
|
|
/* Allocate a new stack. */
|
|
stack = last_stack - stack_size;
|
|
|
|
/*
|
|
* Even if stack allocation fails, we don't want to try to use
|
|
* this location again, so unconditionally decrement
|
|
* last_stack. Under normal operating conditions, the most
|
|
* likely reason for an mmap() error is a stack overflow of the
|
|
* adjacent thread stack.
|
|
*/
|
|
last_stack -= (stack_size + guardsize);
|
|
|
|
/* Stack: */
|
|
if (mmap(stack, stack_size, PROT_READ | PROT_WRITE, MAP_STACK,
|
|
-1, 0) == MAP_FAILED)
|
|
stack = NULL;
|
|
}
|
|
|
|
return (stack);
|
|
}
|
|
|
|
/* This function must be called with the 'dead thread list' lock held. */
|
|
void
|
|
_thread_stack_free(void *stack, size_t stacksize, size_t guardsize)
|
|
{
|
|
struct stack *spare_stack;
|
|
|
|
spare_stack = (stack + stacksize - sizeof(struct stack));
|
|
/* Round stacksize up to nearest multiple of _pthread_page_size. */
|
|
if (stacksize % _pthread_page_size != 0) {
|
|
spare_stack->stacksize =
|
|
((stacksize / _pthread_page_size) + 1) *
|
|
_pthread_page_size;
|
|
} else
|
|
spare_stack->stacksize = stacksize;
|
|
spare_stack->guardsize = guardsize;
|
|
spare_stack->stackaddr = stack;
|
|
|
|
if (spare_stack->stacksize == PTHREAD_STACK_DEFAULT &&
|
|
spare_stack->guardsize == _pthread_guard_default) {
|
|
/* Default stack/guard size. */
|
|
LIST_INSERT_HEAD(&_dstackq, spare_stack, qe);
|
|
} else {
|
|
/* Non-default stack/guard size. */
|
|
LIST_INSERT_HEAD(&_mstackq, spare_stack, qe);
|
|
}
|
|
}
|