PR kern/38355 lockf deadlock detection is broken after vmlocking
- Fix it; tested with Sun's libMicro. - Use pool_cache. - Use a global lock, so the deadlock detection code is safer.
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@ -1,4 +1,4 @@
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/* $NetBSD: init_main.c,v 1.356 2008/05/27 17:50:03 ad Exp $ */
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/* $NetBSD: init_main.c,v 1.357 2008/05/28 13:35:32 ad Exp $ */
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/*-
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* Copyright (c) 2008 The NetBSD Foundation, Inc.
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@ -97,7 +97,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.356 2008/05/27 17:50:03 ad Exp $");
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__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.357 2008/05/28 13:35:32 ad Exp $");
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#include "opt_ipsec.h"
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#include "opt_ntp.h"
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@ -160,6 +160,7 @@ __KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.356 2008/05/27 17:50:03 ad Exp $");
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#include <sys/msgbuf.h>
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#include <sys/module.h>
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#include <sys/event.h>
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#include <sys/lockf.h>
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#ifdef FAST_IPSEC
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#include <netipsec/ipsec.h>
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#endif
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@ -443,6 +444,7 @@ main(void)
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desiredvnodes = usevnodes;
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#endif
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vfsinit();
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lf_init();
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/* Initialize fstrans. */
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fstrans_init();
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@ -1,4 +1,4 @@
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/* $NetBSD: vfs_lockf.c,v 1.64 2008/04/24 18:39:24 ad Exp $ */
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/* $NetBSD: vfs_lockf.c,v 1.65 2008/05/28 13:35:32 ad Exp $ */
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/*
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* Copyright (c) 1982, 1986, 1989, 1993
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@ -35,7 +35,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: vfs_lockf.c,v 1.64 2008/04/24 18:39:24 ad Exp $");
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__KERNEL_RCSID(0, "$NetBSD: vfs_lockf.c,v 1.65 2008/05/28 13:35:32 ad Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -65,6 +65,7 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_lockf.c,v 1.64 2008/04/24 18:39:24 ad Exp $");
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TAILQ_HEAD(locklist, lockf);
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struct lockf {
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kcondvar_t lf_cv; /* Signalling */
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short lf_flags; /* Lock semantics: F_POSIX, F_FLOCK, F_WAIT */
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short lf_type; /* Lock type: F_RDLCK, F_WRLCK */
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off_t lf_start; /* The byte # of the start of the lock */
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@ -75,14 +76,14 @@ struct lockf {
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struct locklist lf_blkhd; /* List of requests blocked on this lock */
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TAILQ_ENTRY(lockf) lf_block;/* A request waiting for a lock */
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uid_t lf_uid; /* User ID responsible */
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kcondvar_t lf_cv; /* Signalling */
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};
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/* Maximum length of sleep chains to traverse to try and detect deadlock. */
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#define MAXDEPTH 50
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static POOL_INIT(lockfpool, sizeof(struct lockf), 0, 0, 0, "lockfpl",
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&pool_allocator_nointr, IPL_NONE);
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static pool_cache_t lockf_cache;
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static kmutex_t *lockf_lock;
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static char lockstr[] = "lockf";
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/*
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* This variable controls the maximum number of processes that will
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@ -202,9 +203,8 @@ lf_alloc(uid_t uid, int allowfail)
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return NULL;
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}
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lock = pool_get(&lockfpool, PR_WAITOK);
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lock = pool_cache_get(lockf_cache, PR_WAITOK);
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lock->lf_uid = uid;
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cv_init(&lock->lf_cv, "lockf");
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return lock;
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}
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@ -215,9 +215,27 @@ lf_free(struct lockf *lock)
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uip = uid_find(lock->lf_uid);
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atomic_dec_ulong(&uip->ui_lockcnt);
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pool_cache_put(lockf_cache, lock);
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}
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static int
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lf_ctor(void *arg, void *obj, int flag)
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{
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struct lockf *lock;
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lock = obj;
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cv_init(&lock->lf_cv, lockstr);
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return 0;
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}
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static void
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lf_dtor(void *arg, void *obj)
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{
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struct lockf *lock;
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lock = obj;
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cv_destroy(&lock->lf_cv);
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pool_put(&lockfpool, lock);
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}
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/*
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@ -502,7 +520,6 @@ lf_setlock(struct lockf *lock, struct lockf **sparelock,
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struct lockf *block;
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struct lockf **head = lock->lf_head;
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struct lockf **prev, *overlap, *ltmp;
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static char lockstr[] = "lockf";
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int ovcase, needtolink, error;
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#ifdef LOCKF_DEBUG
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@ -510,13 +527,6 @@ lf_setlock(struct lockf *lock, struct lockf **sparelock,
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lf_print("lf_setlock", lock);
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#endif /* LOCKF_DEBUG */
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/*
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* XXX Here we used to set the sleep priority so that writers
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* took priority. That's of dubious use, and is not possible
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* with condition variables. Need to find a better way to ensure
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* fairness.
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*/
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/*
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* Scan lock list for this file looking for locks that would block us.
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*/
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@ -555,7 +565,8 @@ lf_setlock(struct lockf *lock, struct lockf **sparelock,
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}
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wlwp = LIST_FIRST(&p->p_lwps);
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lwp_lock(wlwp);
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if (wlwp->l_wmesg != lockstr) {
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if (wlwp->l_wchan == NULL ||
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wlwp->l_wmesg != lockstr) {
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lwp_unlock(wlwp);
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mutex_exit(p->p_lock);
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break;
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@ -616,7 +627,7 @@ lf_setlock(struct lockf *lock, struct lockf **sparelock,
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error = cv_wait_sig(&lock->lf_cv, interlock);
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/*
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* We may have been awakened by a signal (in
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* We may have been awoken by a signal (in
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* which case we must remove ourselves from the
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* blocked list) and/or by another process
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* releasing a lock (in which case we have already
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@ -803,7 +814,7 @@ lf_advlock(struct vop_advlock_args *ap, struct lockf **head, off_t size)
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struct flock *fl = ap->a_fl;
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struct lockf *lock = NULL;
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struct lockf *sparelock;
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kmutex_t *interlock = &ap->a_vp->v_interlock;
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kmutex_t *interlock = lockf_lock;
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off_t start, end;
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int error = 0;
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@ -890,12 +901,6 @@ lf_advlock(struct vop_advlock_args *ap, struct lockf **head, off_t size)
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*/
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lock->lf_start = start;
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lock->lf_end = end;
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/* XXX NJWLWP
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* I don't want to make the entire VFS universe use LWPs, because
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* they don't need them, for the most part. This is an exception,
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* and a kluge.
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*/
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lock->lf_head = head;
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lock->lf_type = fl->l_type;
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lock->lf_next = (struct lockf *)0;
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@ -939,3 +944,17 @@ quit:
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return error;
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}
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/*
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* Initialize subsystem. XXX We use a global lock. This could be the
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* vnode interlock, but the deadlock detection code may need to inspect
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* locks belonging to other files.
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*/
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void
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lf_init(void)
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{
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lockf_cache = pool_cache_init(sizeof(struct lockf), 0, 0, 0, "lockf",
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NULL, IPL_NONE, lf_ctor, lf_dtor, NULL);
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lockf_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
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}
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@ -1,4 +1,4 @@
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/* $NetBSD: lockf.h,v 1.18 2006/05/20 12:02:47 yamt Exp $ */
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/* $NetBSD: lockf.h,v 1.19 2008/05/28 13:35:32 ad Exp $ */
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/*
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* Copyright (c) 1991, 1993
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@ -41,6 +41,7 @@
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struct lockf;
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int lf_advlock(struct vop_advlock_args *, struct lockf **, off_t);
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void lf_init(void);
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#endif /* _KERNEL */
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#endif /* !_SYS_LOCKF_H_ */
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