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do umtx_wake at userland thread exit address, so that others userland

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threads can wait for a thread to exit, and safely assume that the thread
has left userland and is no longer using its userland stack, this is
necessary for pthread_join when a thread is waiting for another thread
to exit which has user customized stack, after pthread_join returns,
the userland stack can be reused for other purposes, without this change,
the joiner thread has to spin at the address to ensure the thread is really
exited.
This commit is contained in:
David Xu 2005-10-26 06:55:46 +00:00
parent 7f3cc43211
commit 4938faa635
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=151692
3 changed files with 10 additions and 4 deletions
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6
sys/kern/kern_thr.c
View File

@ -42,6 +42,8 @@ __FBSDID("$FreeBSD$");
#include <sys/signalvar.h>
#include <sys/ucontext.h>
#include <sys/thr.h>
#include <sys/umtx.h>
#include <sys/limits.h>
#include <machine/frame.h>
@ -275,8 +277,10 @@ thr_exit(struct thread *td, struct thr_exit_args *uap)
p = td->td_proc;
/* Signal userland that it can free the stack. */
if ((void *)uap->state != NULL)
if ((void *)uap->state != NULL) {
suword((void *)uap->state, 1);
kern_umtx_wake(td, uap->state, INT_MAX);
}
PROC_LOCK(p);
sigqueue_flush(&td->td_sigqueue);

6
sys/kern/kern_umtx.c
View File

@ -687,8 +687,8 @@ do_wait(struct thread *td, struct umtx *umtx, long id, struct timespec *timeout)
return (error);
}
static int
do_wake(struct thread *td, void *uaddr, int n_wake)
int
kern_umtx_wake(struct thread *td, void *uaddr, int n_wake)
{
struct umtx_key key;
int ret;
@ -762,7 +762,7 @@ _umtx_op(struct thread *td, struct _umtx_op_args *uap)
error = do_wait(td, uap->umtx, uap->id, ts);
break;
case UMTX_OP_WAKE:
error = do_wake(td, uap->umtx, uap->id);
error = kern_umtx_wake(td, uap->umtx, uap->id);
break;
default:
error = EINVAL;

2
sys/sys/umtx.h
View File

@ -135,6 +135,8 @@ umtx_wake(struct umtx *umtx, int nr_wakeup)
struct umtx_q *umtxq_alloc(void);
void umtxq_free(struct umtx_q *);
struct thread;
int kern_umtx_wake(struct thread *td, void *uaddr, int n_wake);
#endif /* !_KERNEL */
#endif /* !_SYS_UMTX_H_ */