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Attempt to improve convergence of POSIX semaphore code with style(9).
MFC after: 3 days
This commit is contained in:
Robert Watson
parent
9a55503ec1
commit
8e230e30b7
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=179054
@ -72,7 +72,8 @@ static void sem_free(struct ksem *ksnew);
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static int sem_perm(struct thread *td, struct ksem *ks);
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static void sem_enter(struct proc *p, struct ksem *ks);
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static int sem_leave(struct proc *p, struct ksem *ks);
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static void sem_exechook(void *arg, struct proc *p, struct image_params *imgp);
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static void sem_exechook(void *arg, struct proc *p,
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struct image_params *imgp);
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static void sem_exithook(void *arg, struct proc *p);
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static void sem_forkhook(void *arg, struct proc *p1, struct proc *p2,
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int flags);
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@ -89,21 +90,22 @@ static int kern_sem_open(struct thread *td, int dir, const char *name,
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static int kern_sem_unlink(struct thread *td, const char *name);
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#ifndef SEM_MAX
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#define SEM_MAX 30
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#define SEM_MAX 30
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#endif
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#define SEM_MAX_NAMELEN 14
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#define SEM_MAX_NAMELEN 14
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#define SEM_TO_ID(x) ((intptr_t)(x))
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#define ID_TO_SEM(x) id_to_sem(x)
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#define SEM_TO_ID(x) ((intptr_t)(x))
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#define ID_TO_SEM(x) id_to_sem(x)
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/*
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* available semaphores go here, this includes sem_init and any semaphores
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* Available semaphores go here, this includes sem_init and any semaphores
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* created via sem_open that have not yet been unlinked.
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*/
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LIST_HEAD(, ksem) ksem_head = LIST_HEAD_INITIALIZER(&ksem_head);
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/*
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* semaphores still in use but have been sem_unlink()'d go here.
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* Semaphores still in use but have been sem_unlink()'d go here.
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*/
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LIST_HEAD(, ksem) ksem_deadhead = LIST_HEAD_INITIALIZER(&ksem_deadhead);
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@ -117,13 +119,12 @@ SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0, "");
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static eventhandler_tag sem_exit_tag, sem_exec_tag, sem_fork_tag;
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#ifdef SEM_DEBUG
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#define DP(x) printf x
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#define DP(x) printf x
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#else
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#define DP(x)
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#define DP(x)
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#endif
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static __inline
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void
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static __inline void
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sem_ref(struct ksem *ks)
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{
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@ -132,8 +133,7 @@ sem_ref(struct ksem *ks)
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DP(("sem_ref: ks = %p, ref = %d\n", ks, ks->ks_ref));
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}
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static __inline
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void
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static __inline void
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sem_rel(struct ksem *ks)
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{
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@ -143,8 +143,6 @@ sem_rel(struct ksem *ks)
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sem_free(ks);
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}
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static __inline struct ksem *id_to_sem(semid_t id);
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static __inline
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struct ksem *
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id_to_sem(semid_t id)
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@ -195,7 +193,8 @@ sem_create(struct thread *td, const char *name, struct ksem **ksret,
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free(ret, M_SEM);
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return (ENAMETOOLONG);
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}
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/* name must start with a '/' but not contain one. */
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/* Name must start with a '/' but not contain one. */
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if (*name != '/' || len < 2 || index(name + 1, '/') != NULL) {
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free(ret, M_SEM);
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return (EINVAL);
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@ -244,10 +243,8 @@ int ksem_init(struct thread *td, struct ksem_init_args *uap);
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int
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ksem_init(struct thread *td, struct ksem_init_args *uap)
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{
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int error;
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error = kern_sem_init(td, UIO_USERSPACE, uap->value, uap->idp);
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return (error);
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return (kern_sem_init(td, UIO_USERSPACE, uap->value, uap->idp));
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}
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static int
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@ -317,6 +314,7 @@ kern_sem_open(struct thread *td, int dir, const char *name, int oflag,
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ksnew = NULL;
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mtx_lock(&sem_lock);
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ks = sem_lookup_byname(name);
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/*
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* If we found it but O_EXCL is set, error.
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*/
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@ -324,6 +322,7 @@ kern_sem_open(struct thread *td, int dir, const char *name, int oflag,
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mtx_unlock(&sem_lock);
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return (EEXIST);
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}
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/*
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* If we didn't find it...
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*/
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@ -335,6 +334,7 @@ kern_sem_open(struct thread *td, int dir, const char *name, int oflag,
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mtx_unlock(&sem_lock);
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return (ENOENT);
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}
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/*
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* We may block during creation, so drop the lock.
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*/
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@ -357,6 +357,7 @@ kern_sem_open(struct thread *td, int dir, const char *name, int oflag,
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DP(("about to set! %d to %p\n", id, idp));
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*idp = id;
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}
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/*
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* We need to make sure we haven't lost a race while
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* allocating during creation.
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@ -454,8 +455,6 @@ sem_free(struct ksem *ks)
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free(ks, M_SEM);
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}
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static __inline struct kuser *sem_getuser(struct proc *p, struct ksem *ks);
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static __inline struct kuser *
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sem_getuser(struct proc *p, struct ksem *ks)
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{
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@ -495,9 +494,7 @@ sem_leave(struct proc *p, struct ksem *ks)
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}
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static void
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sem_enter(p, ks)
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struct proc *p;
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struct ksem *ks;
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sem_enter(struct proc *p, struct ksem *ks)
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{
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struct kuser *ku, *k;
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@ -584,7 +581,10 @@ kern_sem_close(struct thread *td, semid_t id)
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error = EINVAL;
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mtx_lock(&sem_lock);
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ks = ID_TO_SEM(id);
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/* this is not a valid operation for unnamed sems */
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/*
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* This is not a valid operation for unnamed sems.
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*/
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if (ks != NULL && ks->ks_name != NULL)
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error = sem_leave(td->td_proc, ks);
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mtx_unlock(&sem_lock);
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@ -661,7 +661,9 @@ ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
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struct timespec *ts;
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int error;
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/* We allow a null timespec (wait forever). */
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/*
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* We allow a null timespec (wait forever).
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*/
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if (uap->abstime == NULL)
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ts = NULL;
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else {
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@ -885,6 +887,7 @@ sem_forkhook(void *arg, struct proc *p1, struct proc *p2, int flags)
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count = new_count;
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goto race_lost;
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}
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/*
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* Given an array capable of storing an adequate number of semaphore
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* references, now walk the list of semaphores and acquire a new
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@ -914,6 +917,7 @@ sem_forkhook(void *arg, struct proc *p1, struct proc *p2, int flags)
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}
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mtx_unlock(&sem_lock);
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KASSERT(i == count, ("sem_forkhook: i != count (%d, %d)", i, count));
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/*
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* Now cause p2 to enter each of the referenced semaphores, then
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* release our temporary reference. This is pretty inefficient.
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@ -965,12 +969,14 @@ sem_modload(struct module *module, int cmd, void *arg)
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mtx_init(&sem_lock, "sem", "semaphore", MTX_DEF);
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p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
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p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
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sem_exit_tag = EVENTHANDLER_REGISTER(process_exit, sem_exithook,
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NULL, EVENTHANDLER_PRI_ANY);
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sem_exec_tag = EVENTHANDLER_REGISTER(process_exec, sem_exechook,
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NULL, EVENTHANDLER_PRI_ANY);
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sem_fork_tag = EVENTHANDLER_REGISTER(process_fork, sem_forkhook, NULL, EVENTHANDLER_PRI_ANY);
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sem_exit_tag = EVENTHANDLER_REGISTER(process_exit,
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sem_exithook, NULL, EVENTHANDLER_PRI_ANY);
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sem_exec_tag = EVENTHANDLER_REGISTER(process_exec,
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sem_exechook, NULL, EVENTHANDLER_PRI_ANY);
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sem_fork_tag = EVENTHANDLER_REGISTER(process_fork,
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sem_forkhook, NULL, EVENTHANDLER_PRI_ANY);
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break;
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case MOD_UNLOAD:
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if (nsems != 0) {
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error = EOPNOTSUPP;
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@ -981,6 +987,7 @@ sem_modload(struct module *module, int cmd, void *arg)
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EVENTHANDLER_DEREGISTER(process_fork, sem_fork_tag);
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mtx_destroy(&sem_lock);
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break;
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case MOD_SHUTDOWN:
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break;
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default:
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