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fix F_SETLKW deadlock detection, which has been broken since lwpify. 

although this doesn't work for processes with multiple lwps, it's better
than not working at all.
This commit is contained in:
yamt 2006-05-20 12:06:20 +00:00
parent cecc761849
commit a6518311cc
1 changed files with 28 additions and 14 deletions
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42
sys/kern/vfs_lockf.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vfs_lockf.c,v 1.51 2006/05/20 12:04:21 yamt Exp $ */
/* $NetBSD: vfs_lockf.c,v 1.52 2006/05/20 12:06:20 yamt Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_lockf.c,v 1.51 2006/05/20 12:04:21 yamt Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_lockf.c,v 1.52 2006/05/20 12:06:20 yamt Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -69,7 +69,6 @@ struct lockf {
off_t lf_start; /* The byte # of the start of the lock */
off_t lf_end; /* The byte # of the end of the lock (-1=EOF)*/
void *lf_id; /* process or file description holding lock */
struct lwp *lf_lwp; /* LWP waiting for lock */
struct lockf **lf_head; /* Back pointer to the head of lockf list */
struct lockf *lf_next; /* Next lock on this vnode, or blocking lock */
struct locklist lf_blkhd; /* List of requests blocked on this lock */
@ -544,22 +543,39 @@ lf_setlock(struct lockf *lock, struct lockf **sparelock,
struct lwp *wlwp;
volatile const struct lockf *waitblock;
int i = 0;
struct proc *p;
/*
* The block is waiting on something. if_lwp will be
* 0 once the lock is granted, so we terminate the
* loop if we find this.
*/
wlwp = block->lf_lwp;
while (wlwp && (i++ < maxlockdepth)) {
p = (struct proc *)block->lf_id;
KASSERT(p != NULL);
while (i++ < maxlockdepth) {
simple_lock(&p->p_lock);
if (p->p_nlwps > 1) {
simple_unlock(&p->p_lock);
break;
}
wlwp = LIST_FIRST(&p->p_lwps);
if (wlwp->l_wmesg != lockstr) {
simple_unlock(&p->p_lock);
break;
}
simple_unlock(&p->p_lock);
waitblock = wlwp->l_wchan;
if (waitblock == NULL) {
/*
* this lwp just got up but
* not returned from ltsleep yet.
*/
break;
}
/* Get the owner of the blocking lock */
waitblock = waitblock->lf_next;
if ((waitblock->lf_flags & F_POSIX) == 0)
break;
wlwp = waitblock->lf_lwp;
if (wlwp == lock->lf_lwp) {
p = (struct proc *)waitblock->lf_id;
if (p == curproc) {
lf_free(lock);
printf("deadlock detected pid=%d\n",
(int)curproc->p_pid);
return EDEADLK;
}
}
@ -623,7 +639,6 @@ lf_setlock(struct lockf *lock, struct lockf **sparelock,
* Skip over locks owned by other processes.
* Handle any locks that overlap and are owned by ourselves.
*/
lock->lf_lwp = 0;
prev = head;
block = *head;
needtolink = 1;
@ -888,7 +903,6 @@ lf_advlock(struct vop_advlock_args *ap, struct lockf **head, off_t size)
KASSERT(curproc == (struct proc *)ap->a_id);
}
lock->lf_id = (struct proc *)ap->a_id;
lock->lf_lwp = curlwp;
/*
* Do the requested operation.