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Close a race between a thread exiting and the freeing of it's stack.

Browse Source 
After some discussion the best option seems to be to signal the thread's
death from within the kernel. This requires that thr_exit() take an
argument.

Discussed with: davidxu, deischen, marcel
MFC after: 3 days
This commit is contained in:
mtm 2004-10-06 14:23:00 +00:00
parent 66f574f537
commit 0a21f474dc
8 changed files with 14 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
lib/libthr/thread/thr_exit.c
View File

@ -43,7 +43,7 @@
__weak_reference(_pthread_exit, pthread_exit);
/* thr_exit() */
extern int _thr_exit(void);
extern int _thr_exit(long *state);
static void deadlist_free_threads();
@ -164,7 +164,6 @@ _pthread_exit(void *status)
deadlist_free_threads();
TAILQ_INSERT_HEAD(&_dead_list, curthread, dle);
TAILQ_REMOVE(&_thread_list, curthread, tle);
curthread->isdead = 1;
/* If we're the last thread, call it quits */
if (TAILQ_EMPTY(&_thread_list))
@ -181,7 +180,7 @@ _pthread_exit(void *status)
* thread, which we can't be because we've already checked
* for that.
*/
_thr_exit();
_thr_exit((long *)&curthread->isdead);
/* This point should not be reached. */
PANIC("Dead thread has resumed");

2
sys/compat/freebsd32/freebsd32_proto.h
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@ -3,7 +3,7 @@
*
* DO NOT EDIT-- this file is automatically generated.
* $FreeBSD$
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.40 2004/07/14 00:03:30 peter Exp
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.41 2004/10/06 14:20:57 mtm Exp
*/
#ifndef _FREEBSD32_SYSPROTO_H_

2
sys/compat/freebsd32/freebsd32_syscall.h
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@ -3,7 +3,7 @@
*
* DO NOT EDIT-- this file is automatically generated.
* $FreeBSD$
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.40 2004/07/14 00:03:30 peter Exp
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.41 2004/10/06 14:20:57 mtm Exp
*/
#define FREEBSD32_SYS_syscall 0

2
sys/compat/freebsd32/freebsd32_syscalls.c
View File

@ -3,7 +3,7 @@
*
* DO NOT EDIT-- this file is automatically generated.
* $FreeBSD$
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.40 2004/07/14 00:03:30 peter Exp
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.41 2004/10/06 14:20:57 mtm Exp
*/
const char *freebsd32_syscallnames[] = {

4
sys/compat/freebsd32/freebsd32_sysent.c
View File

@ -3,7 +3,7 @@
*
* DO NOT EDIT-- this file is automatically generated.
* $FreeBSD$
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.40 2004/07/14 00:03:30 peter Exp
* created from FreeBSD: src/sys/compat/freebsd32/syscalls.master,v 1.41 2004/10/06 14:20:57 mtm Exp
*/
#include "opt_compat.h"
@ -456,7 +456,7 @@ struct sysent freebsd32_sysent[] = {
{ 0, (sy_call_t *)nosys }, /* 428 = __acl_aclcheck_link */
{ 0, (sy_call_t *)nosys }, /* 429 = sigwait */
{ SYF_MPSAFE | AS(thr_create_args), (sy_call_t *)thr_create }, /* 430 = thr_create */
{ SYF_MPSAFE | 0, (sy_call_t *)thr_exit }, /* 431 = thr_exit */
{ SYF_MPSAFE | AS(thr_exit_args), (sy_call_t *)thr_exit }, /* 431 = thr_exit */
{ SYF_MPSAFE | AS(thr_self_args), (sy_call_t *)thr_self }, /* 432 = thr_self */
{ SYF_MPSAFE | AS(thr_kill_args), (sy_call_t *)thr_kill }, /* 433 = thr_kill */
{ SYF_MPSAFE | AS(_umtx_lock_args), (sy_call_t *)_umtx_lock }, /* 434 = _umtx_lock */

2
sys/compat/freebsd32/syscalls.master
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@ -596,7 +596,7 @@
; XXX implement
429 UNIMPL sigwait
430 MNOPROTO { int thr_create(ucontext_t *ctx, long *id, int flag s); }
431 MNOPROTO { void thr_exit(void); }
431 MNOPROTO { void thr_exit(long *state); }
432 MNOPROTO { int thr_self(long *id); }
433 MNOPROTO { int thr_kill(long id, int sig); }
434 MNOPROTO { int _umtx_lock(struct umtx *umtx); }

6
sys/kern/kern_thr.c
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@ -186,12 +186,16 @@ thr_self(struct thread *td, struct thr_self_args *uap)
int
thr_exit(struct thread *td, struct thr_exit_args *uap)
/* NULL */
/* long *state */
{
struct proc *p;
p = td->td_proc;
/* Signal userland that it can free the stack. */
if ((void *)uap->state != NULL)
suword((void *)uap->state, 1);
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);

2
sys/sys/thr.h
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@ -39,7 +39,7 @@
int thr_create(ucontext_t *ctx, long *id, int flags);
int thr_self(long *id);
void thr_exit(void);
void thr_exit(long *state);
int thr_kill(long id, int sig);
int thr_suspend(const struct timespec *timeout);
int thr_wake(long id);