initial_commit

1 files changed, 1647 insertions, 0 deletions

diff --git a/ipc/sem.c b/ipc/sem.c
new file mode 100644
index 00000000..e68a8f57
--- /dev/null
+++ b/ipc/sem.c
@@ -0,0 +1,1647 @@
+/*
+ * linux/ipc/sem.c
+ * Copyright (C) 1992 Krishna Balasubramanian
+ * Copyright (C) 1995 Eric Schenk, Bruno Haible
+ *
+ * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
+ *
+ * SMP-threaded, sysctl's added
+ * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
+ * Enforced range limit on SEM_UNDO
+ * (c) 2001 Red Hat Inc
+ * Lockless wakeup
+ * (c) 2003 Manfred Spraul <manfred@colorfullife.com>
+ * Further wakeup optimizations, documentation
+ * (c) 2010 Manfred Spraul <manfred@colorfullife.com>
+ *
+ * support for audit of ipc object properties and permission changes
+ * Dustin Kirkland <dustin.kirkland@us.ibm.com>
+ *
+ * namespaces support
+ * OpenVZ, SWsoft Inc.
+ * Pavel Emelianov <xemul@openvz.org>
+ *
+ * Implementation notes: (May 2010)
+ * This file implements System V semaphores.
+ *
+ * User space visible behavior:
+ * - FIFO ordering for semop() operations (just FIFO, not starvation
+ *   protection)
+ * - multiple semaphore operations that alter the same semaphore in
+ *   one semop() are handled.
+ * - sem_ctime (time of last semctl()) is updated in the IPC_SET, SETVAL and
+ *   SETALL calls.
+ * - two Linux specific semctl() commands: SEM_STAT, SEM_INFO.
+ * - undo adjustments at process exit are limited to 0..SEMVMX.
+ * - namespace are supported.
+ * - SEMMSL, SEMMNS, SEMOPM and SEMMNI can be configured at runtine by writing
+ *   to /proc/sys/kernel/sem.
+ * - statistics about the usage are reported in /proc/sysvipc/sem.
+ *
+ * Internals:
+ * - scalability:
+ *   - all global variables are read-mostly.
+ *   - semop() calls and semctl(RMID) are synchronized by RCU.
+ *   - most operations do write operations (actually: spin_lock calls) to
+ *     the per-semaphore array structure.
+ *   Thus: Perfect SMP scaling between independent semaphore arrays.
+ *         If multiple semaphores in one array are used, then cache line
+ *         trashing on the semaphore array spinlock will limit the scaling.
+ * - semncnt and semzcnt are calculated on demand in count_semncnt() and
+ *   count_semzcnt()
+ * - the task that performs a successful semop() scans the list of all
+ *   sleeping tasks and completes any pending operations that can be fulfilled.
+ *   Semaphores are actively given to waiting tasks (necessary for FIFO).
+ *   (see update_queue())
+ * - To improve the scalability, the actual wake-up calls are performed after
+ *   dropping all locks. (see wake_up_sem_queue_prepare(),
+ *   wake_up_sem_queue_do())
+ * - All work is done by the waker, the woken up task does not have to do
+ *   anything - not even acquiring a lock or dropping a refcount.
+ * - A woken up task may not even touch the semaphore array anymore, it may
+ *   have been destroyed already by a semctl(RMID).
+ * - The synchronizations between wake-ups due to a timeout/signal and a
+ *   wake-up due to a completed semaphore operation is achieved by using an
+ *   intermediate state (IN_WAKEUP).
+ * - UNDO values are stored in an array (one per process and per
+ *   semaphore array, lazily allocated). For backwards compatibility, multiple
+ *   modes for the UNDO variables are supported (per process, per thread)
+ *   (see copy_semundo, CLONE_SYSVSEM)
+ * - There are two lists of the pending operations: a per-array list
+ *   and per-semaphore list (stored in the array). This allows to achieve FIFO
+ *   ordering without always scanning all pending operations.
+ *   The worst-case behavior is nevertheless O(N^2) for N wakeups.
+ */
+
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/time.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <linux/capability.h>
+#include <linux/seq_file.h>
+#include <linux/rwsem.h>
+#include <linux/nsproxy.h>
+#include <linux/ipc_namespace.h>
+
+#include <asm/uaccess.h>
+#include "util.h"
+
+#define sem_ids(ns)	((ns)->ids[IPC_SEM_IDS])
+
+#define sem_unlock(sma)		ipc_unlock(&(sma)->sem_perm)
+#define sem_checkid(sma, semid)	ipc_checkid(&sma->sem_perm, semid)
+
+static int newary(struct ipc_namespace *, struct ipc_params *);
+static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
+#ifdef CONFIG_PROC_FS
+static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
+#endif
+
+#define SEMMSL_FAST	256 /* 512 bytes on stack */
+#define SEMOPM_FAST	64  /* ~ 372 bytes on stack */
+
+/*
+ * linked list protection:
+ *	sem_undo.id_next,
+ *	sem_array.sem_pending{,last},
+ *	sem_array.sem_undo: sem_lock() for read/write
+ *	sem_undo.proc_next: only "current" is allowed to read/write that field.
+ *	
+ */
+
+#define sc_semmsl	sem_ctls[0]
+#define sc_semmns	sem_ctls[1]
+#define sc_semopm	sem_ctls[2]
+#define sc_semmni	sem_ctls[3]
+
+void sem_init_ns(struct ipc_namespace *ns)
+{
+	ns->sc_semmsl = SEMMSL;
+	ns->sc_semmns = SEMMNS;
+	ns->sc_semopm = SEMOPM;
+	ns->sc_semmni = SEMMNI;
+	ns->used_sems = 0;
+	ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
+}
+
+#ifdef CONFIG_IPC_NS
+void sem_exit_ns(struct ipc_namespace *ns)
+{
+	free_ipcs(ns, &sem_ids(ns), freeary);
+	idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr);
+}
+#endif
+
+void __init sem_init (void)
+{
+	sem_init_ns(&init_ipc_ns);
+	ipc_init_proc_interface("sysvipc/sem",
+				"       key      semid perms      nsems   uid   gid  cuid  cgid      otime      ctime\n",
+				IPC_SEM_IDS, sysvipc_sem_proc_show);
+}
+
+/*
+ * sem_lock_(check_) routines are called in the paths where the rw_mutex
+ * is not held.
+ */
+static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
+{
+	struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);
+
+	if (IS_ERR(ipcp))
+		return (struct sem_array *)ipcp;
+
+	return container_of(ipcp, struct sem_array, sem_perm);
+}
+
+static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns,
+						int id)
+{
+	struct kern_ipc_perm *ipcp = ipc_lock_check(&sem_ids(ns), id);
+
+	if (IS_ERR(ipcp))
+		return (struct sem_array *)ipcp;
+
+	return container_of(ipcp, struct sem_array, sem_perm);
+}
+
+static inline void sem_lock_and_putref(struct sem_array *sma)
+{
+	ipc_lock_by_ptr(&sma->sem_perm);
+	ipc_rcu_putref(sma);
+}
+
+static inline void sem_getref_and_unlock(struct sem_array *sma)
+{
+	ipc_rcu_getref(sma);
+	ipc_unlock(&(sma)->sem_perm);
+}
+
+static inline void sem_putref(struct sem_array *sma)
+{
+	ipc_lock_by_ptr(&sma->sem_perm);
+	ipc_rcu_putref(sma);
+	ipc_unlock(&(sma)->sem_perm);
+}
+
+static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
+{
+	ipc_rmid(&sem_ids(ns), &s->sem_perm);
+}
+
+/*
+ * Lockless wakeup algorithm:
+ * Without the check/retry algorithm a lockless wakeup is possible:
+ * - queue.status is initialized to -EINTR before blocking.
+ * - wakeup is performed by
+ *	* unlinking the queue entry from sma->sem_pending
+ *	* setting queue.status to IN_WAKEUP
+ *	  This is the notification for the blocked thread that a
+ *	  result value is imminent.
+ *	* call wake_up_process
+ *	* set queue.status to the final value.
+ * - the previously blocked thread checks queue.status:
+ *   	* if it's IN_WAKEUP, then it must wait until the value changes
+ *   	* if it's not -EINTR, then the operation was completed by
+ *   	  update_queue. semtimedop can return queue.status without
+ *   	  performing any operation on the sem array.
+ *   	* otherwise it must acquire the spinlock and check what's up.
+ *
+ * The two-stage algorithm is necessary to protect against the following
+ * races:
+ * - if queue.status is set after wake_up_process, then the woken up idle
+ *   thread could race forward and try (and fail) to acquire sma->lock
+ *   before update_queue had a chance to set queue.status
+ * - if queue.status is written before wake_up_process and if the
+ *   blocked process is woken up by a signal between writing
+ *   queue.status and the wake_up_process, then the woken up
+ *   process could return from semtimedop and die by calling
+ *   sys_exit before wake_up_process is called. Then wake_up_process
+ *   will oops, because the task structure is already invalid.
+ *   (yes, this happened on s390 with sysv msg).
+ *
+ */
+#define IN_WAKEUP	1
+
+/**
+ * newary - Create a new semaphore set
+ * @ns: namespace
+ * @params: ptr to the structure that contains key, semflg and nsems
+ *
+ * Called with sem_ids.rw_mutex held (as a writer)
+ */
+
+static int newary(struct ipc_namespace *ns, struct ipc_params *params)
+{
+	int id;
+	int retval;
+	struct sem_array *sma;
+	int size;
+	key_t key = params->key;
+	int nsems = params->u.nsems;
+	int semflg = params->flg;
+	int i;
+
+	if (!nsems)
+		return -EINVAL;
+	if (ns->used_sems + nsems > ns->sc_semmns)
+		return -ENOSPC;
+
+	size = sizeof (*sma) + nsems * sizeof (struct sem);
+	sma = ipc_rcu_alloc(size);
+	if (!sma) {
+		return -ENOMEM;
+	}
+	memset (sma, 0, size);
+
+	sma->sem_perm.mode = (semflg & S_IRWXUGO);
+	sma->sem_perm.key = key;
+
+	sma->sem_perm.security = NULL;
+	retval = security_sem_alloc(sma);
+	if (retval) {
+		ipc_rcu_putref(sma);
+		return retval;
+	}
+
+	id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
+	if (id < 0) {
+		security_sem_free(sma);
+		ipc_rcu_putref(sma);
+		return id;
+	}
+	ns->used_sems += nsems;
+
+	sma->sem_base = (struct sem *) &sma[1];
+
+	for (i = 0; i < nsems; i++)
+		INIT_LIST_HEAD(&sma->sem_base[i].sem_pending);
+
+	sma->complex_count = 0;
+	INIT_LIST_HEAD(&sma->sem_pending);
+	INIT_LIST_HEAD(&sma->list_id);
+	sma->sem_nsems = nsems;
+	sma->sem_ctime = get_seconds();
+	sem_unlock(sma);
+
+	return sma->sem_perm.id;
+}
+
+
+/*
+ * Called with sem_ids.rw_mutex and ipcp locked.
+ */
+static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
+{
+	struct sem_array *sma;
+
+	sma = container_of(ipcp, struct sem_array, sem_perm);
+	return security_sem_associate(sma, semflg);
+}
+
+/*
+ * Called with sem_ids.rw_mutex and ipcp locked.
+ */
+static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
+				struct ipc_params *params)
+{
+	struct sem_array *sma;
+
+	sma = container_of(ipcp, struct sem_array, sem_perm);
+	if (params->u.nsems > sma->sem_nsems)
+		return -EINVAL;
+
+	return 0;
+}
+
+SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
+{
+	struct ipc_namespace *ns;
+	struct ipc_ops sem_ops;
+	struct ipc_params sem_params;
+
+	ns = current->nsproxy->ipc_ns;
+
+	if (nsems < 0 || nsems > ns->sc_semmsl)
+		return -EINVAL;
+
+	sem_ops.getnew = newary;
+	sem_ops.associate = sem_security;
+	sem_ops.more_checks = sem_more_checks;
+
+	sem_params.key = key;
+	sem_params.flg = semflg;
+	sem_params.u.nsems = nsems;
+
+	return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
+}
+
+/*
+ * Determine whether a sequence of semaphore operations would succeed
+ * all at once. Return 0 if yes, 1 if need to sleep, else return error code.
+ */
+
+static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops,
+			     int nsops, struct sem_undo *un, int pid)
+{
+	int result, sem_op;
+	struct sembuf *sop;
+	struct sem * curr;
+
+	for (sop = sops; sop < sops + nsops; sop++) {
+		curr = sma->sem_base + sop->sem_num;
+		sem_op = sop->sem_op;
+		result = curr->semval;
+  
+		if (!sem_op && result)
+			goto would_block;
+
+		result += sem_op;
+		if (result < 0)
+			goto would_block;
+		if (result > SEMVMX)
+			goto out_of_range;
+		if (sop->sem_flg & SEM_UNDO) {
+			int undo = un->semadj[sop->sem_num] - sem_op;
+			/*
+	 		 *	Exceeding the undo range is an error.
+			 */
+			if (undo < (-SEMAEM - 1) || undo > SEMAEM)
+				goto out_of_range;
+		}
+		curr->semval = result;
+	}
+
+	sop--;
+	while (sop >= sops) {
+		sma->sem_base[sop->sem_num].sempid = pid;
+		if (sop->sem_flg & SEM_UNDO)
+			un->semadj[sop->sem_num] -= sop->sem_op;
+		sop--;
+	}
+	
+	return 0;
+
+out_of_range:
+	result = -ERANGE;
+	goto undo;
+
+would_block:
+	if (sop->sem_flg & IPC_NOWAIT)
+		result = -EAGAIN;
+	else
+		result = 1;
+
+undo:
+	sop--;
+	while (sop >= sops) {
+		sma->sem_base[sop->sem_num].semval -= sop->sem_op;
+		sop--;
+	}
+
+	return result;
+}
+
+/** wake_up_sem_queue_prepare(q, error): Prepare wake-up
+ * @q: queue entry that must be signaled
+ * @error: Error value for the signal
+ *
+ * Prepare the wake-up of the queue entry q.
+ */
+static void wake_up_sem_queue_prepare(struct list_head *pt,
+				struct sem_queue *q, int error)
+{
+	if (list_empty(pt)) {
+		/*
+		 * Hold preempt off so that we don't get preempted and have the
+		 * wakee busy-wait until we're scheduled back on.
+		 */
+		preempt_disable();
+	}
+	q->status = IN_WAKEUP;
+	q->pid = error;
+
+	list_add_tail(&q->simple_list, pt);
+}
+
+/**
+ * wake_up_sem_queue_do(pt) - do the actual wake-up
+ * @pt: list of tasks to be woken up
+ *
+ * Do the actual wake-up.
+ * The function is called without any locks held, thus the semaphore array
+ * could be destroyed already and the tasks can disappear as soon as the
+ * status is set to the actual return code.
+ */
+static void wake_up_sem_queue_do(struct list_head *pt)
+{
+	struct sem_queue *q, *t;
+	int did_something;
+
+	did_something = !list_empty(pt);
+	list_for_each_entry_safe(q, t, pt, simple_list) {
+		wake_up_process(q->sleeper);
+		/* q can disappear immediately after writing q->status. */
+		smp_wmb();
+		q->status = q->pid;
+	}
+	if (did_something)
+		preempt_enable();
+}
+
+static void unlink_queue(struct sem_array *sma, struct sem_queue *q)
+{
+	list_del(&q->list);
+	if (q->nsops == 1)
+		list_del(&q->simple_list);
+	else
+		sma->complex_count--;
+}
+
+/** check_restart(sma, q)
+ * @sma: semaphore array
+ * @q: the operation that just completed
+ *
+ * update_queue is O(N^2) when it restarts scanning the whole queue of
+ * waiting operations. Therefore this function checks if the restart is
+ * really necessary. It is called after a previously waiting operation
+ * was completed.
+ */
+static int check_restart(struct sem_array *sma, struct sem_queue *q)
+{
+	struct sem *curr;
+	struct sem_queue *h;
+
+	/* if the operation didn't modify the array, then no restart */
+	if (q->alter == 0)
+		return 0;
+
+	/* pending complex operations are too difficult to analyse */
+	if (sma->complex_count)
+		return 1;
+
+	/* we were a sleeping complex operation. Too difficult */
+	if (q->nsops > 1)
+		return 1;
+
+	curr = sma->sem_base + q->sops[0].sem_num;
+
+	/* No-one waits on this queue */
+	if (list_empty(&curr->sem_pending))
+		return 0;
+
+	/* the new semaphore value */
+	if (curr->semval) {
+		/* It is impossible that someone waits for the new value:
+		 * - q is a previously sleeping simple operation that
+		 *   altered the array. It must be a decrement, because
+		 *   simple increments never sleep.
+		 * - The value is not 0, thus wait-for-zero won't proceed.
+		 * - If there are older (higher priority) decrements
+		 *   in the queue, then they have observed the original
+		 *   semval value and couldn't proceed. The operation
+		 *   decremented to value - thus they won't proceed either.
+		 */
+		BUG_ON(q->sops[0].sem_op >= 0);
+		return 0;
+	}
+	/*
+	 * semval is 0. Check if there are wait-for-zero semops.
+	 * They must be the first entries in the per-semaphore simple queue
+	 */
+	h = list_first_entry(&curr->sem_pending, struct sem_queue, simple_list);
+	BUG_ON(h->nsops != 1);
+	BUG_ON(h->sops[0].sem_num != q->sops[0].sem_num);
+
+	/* Yes, there is a wait-for-zero semop. Restart */
+	if (h->sops[0].sem_op == 0)
+		return 1;
+
+	/* Again - no-one is waiting for the new value. */
+	return 0;
+}
+
+
+/**
+ * update_queue(sma, semnum): Look for tasks that can be completed.
+ * @sma: semaphore array.
+ * @semnum: semaphore that was modified.
+ * @pt: list head for the tasks that must be woken up.
+ *
+ * update_queue must be called after a semaphore in a semaphore array
+ * was modified. If multiple semaphore were modified, then @semnum
+ * must be set to -1.
+ * The tasks that must be woken up are added to @pt. The return code
+ * is stored in q->pid.
+ * The function return 1 if at least one semop was completed successfully.
+ */
+static int update_queue(struct sem_array *sma, int semnum, struct list_head *pt)
+{
+	struct sem_queue *q;
+	struct list_head *walk;
+	struct list_head *pending_list;
+	int offset;
+	int semop_completed = 0;
+
+	/* if there are complex operations around, then knowing the semaphore
+	 * that was modified doesn't help us. Assume that multiple semaphores
+	 * were modified.
+	 */
+	if (sma->complex_count)
+		semnum = -1;
+
+	if (semnum == -1) {
+		pending_list = &sma->sem_pending;
+		offset = offsetof(struct sem_queue, list);
+	} else {
+		pending_list = &sma->sem_base[semnum].sem_pending;
+		offset = offsetof(struct sem_queue, simple_list);
+	}
+
+again:
+	walk = pending_list->next;
+	while (walk != pending_list) {
+		int error, restart;
+
+		q = (struct sem_queue *)((char *)walk - offset);
+		walk = walk->next;
+
+		/* If we are scanning the single sop, per-semaphore list of
+		 * one semaphore and that semaphore is 0, then it is not
+		 * necessary to scan the "alter" entries: simple increments
+		 * that affect only one entry succeed immediately and cannot
+		 * be in the  per semaphore pending queue, and decrements
+		 * cannot be successful if the value is already 0.
+		 */
+		if (semnum != -1 && sma->sem_base[semnum].semval == 0 &&
+				q->alter)
+			break;
+
+		error = try_atomic_semop(sma, q->sops, q->nsops,
+					 q->undo, q->pid);
+
+		/* Does q->sleeper still need to sleep? */
+		if (error > 0)
+			continue;
+
+		unlink_queue(sma, q);
+
+		if (error) {
+			restart = 0;
+		} else {
+			semop_completed = 1;
+			restart = check_restart(sma, q);
+		}
+
+		wake_up_sem_queue_prepare(pt, q, error);
+		if (restart)
+			goto again;
+	}
+	return semop_completed;
+}
+
+/**
+ * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue
+ * @sma: semaphore array
+ * @sops: operations that were performed
+ * @nsops: number of operations
+ * @otime: force setting otime
+ * @pt: list head of the tasks that must be woken up.
+ *
+ * do_smart_update() does the required called to update_queue, based on the
+ * actual changes that were performed on the semaphore array.
+ * Note that the function does not do the actual wake-up: the caller is
+ * responsible for calling wake_up_sem_queue_do(@pt).
+ * It is safe to perform this call after dropping all locks.
+ */
+static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops,
+			int otime, struct list_head *pt)
+{
+	int i;
+
+	if (sma->complex_count || sops == NULL) {
+		if (update_queue(sma, -1, pt))
+			otime = 1;
+		goto done;
+	}
+
+	for (i = 0; i < nsops; i++) {
+		if (sops[i].sem_op > 0 ||
+			(sops[i].sem_op < 0 &&
+				sma->sem_base[sops[i].sem_num].semval == 0))
+			if (update_queue(sma, sops[i].sem_num, pt))
+				otime = 1;
+	}
+done:
+	if (otime)
+		sma->sem_otime = get_seconds();
+}
+
+
+/* The following counts are associated to each semaphore:
+ *   semncnt        number of tasks waiting on semval being nonzero
+ *   semzcnt        number of tasks waiting on semval being zero
+ * This model assumes that a task waits on exactly one semaphore.
+ * Since semaphore operations are to be performed atomically, tasks actually
+ * wait on a whole sequence of semaphores simultaneously.
+ * The counts we return here are a rough approximation, but still
+ * warrant that semncnt+semzcnt>0 if the task is on the pending queue.
+ */
+static int count_semncnt (struct sem_array * sma, ushort semnum)
+{
+	int semncnt;
+	struct sem_queue * q;
+
+	semncnt = 0;
+	list_for_each_entry(q, &sma->sem_pending, list) {
+		struct sembuf * sops = q->sops;
+		int nsops = q->nsops;
+		int i;
+		for (i = 0; i < nsops; i++)
+			if (sops[i].sem_num == semnum
+			    && (sops[i].sem_op < 0)
+			    && !(sops[i].sem_flg & IPC_NOWAIT))
+				semncnt++;
+	}
+	return semncnt;
+}
+
+static int count_semzcnt (struct sem_array * sma, ushort semnum)
+{
+	int semzcnt;
+	struct sem_queue * q;
+
+	semzcnt = 0;
+	list_for_each_entry(q, &sma->sem_pending, list) {
+		struct sembuf * sops = q->sops;
+		int nsops = q->nsops;
+		int i;
+		for (i = 0; i < nsops; i++)
+			if (sops[i].sem_num == semnum
+			    && (sops[i].sem_op == 0)
+			    && !(sops[i].sem_flg & IPC_NOWAIT))
+				semzcnt++;
+	}
+	return semzcnt;
+}
+
+static void free_un(struct rcu_head *head)
+{
+	struct sem_undo *un = container_of(head, struct sem_undo, rcu);
+	kfree(un);
+}
+
+/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
+ * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
+ * remains locked on exit.
+ */
+static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
+{
+	struct sem_undo *un, *tu;
+	struct sem_queue *q, *tq;
+	struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
+	struct list_head tasks;
+
+	/* Free the existing undo structures for this semaphore set.  */
+	assert_spin_locked(&sma->sem_perm.lock);
+	list_for_each_entry_safe(un, tu, &sma->list_id, list_id) {
+		list_del(&un->list_id);
+		spin_lock(&un->ulp->lock);
+		un->semid = -1;
+		list_del_rcu(&un->list_proc);
+		spin_unlock(&un->ulp->lock);
+		call_rcu(&un->rcu, free_un);
+	}
+
+	/* Wake up all pending processes and let them fail with EIDRM. */
+	INIT_LIST_HEAD(&tasks);
+	list_for_each_entry_safe(q, tq, &sma->sem_pending, list) {
+		unlink_queue(sma, q);
+		wake_up_sem_queue_prepare(&tasks, q, -EIDRM);
+	}
+
+	/* Remove the semaphore set from the IDR */
+	sem_rmid(ns, sma);
+	sem_unlock(sma);
+
+	wake_up_sem_queue_do(&tasks);
+	ns->used_sems -= sma->sem_nsems;
+	security_sem_free(sma);
+	ipc_rcu_putref(sma);
+}
+
+static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
+{
+	switch(version) {
+	case IPC_64:
+		return copy_to_user(buf, in, sizeof(*in));
+	case IPC_OLD:
+	    {
+		struct semid_ds out;
+
+		memset(&out, 0, sizeof(out));
+
+		ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
+
+		out.sem_otime	= in->sem_otime;
+		out.sem_ctime	= in->sem_ctime;
+		out.sem_nsems	= in->sem_nsems;
+
+		return copy_to_user(buf, &out, sizeof(out));
+	    }
+	default:
+		return -EINVAL;
+	}
+}
+
+static int semctl_nolock(struct ipc_namespace *ns, int semid,
+			 int cmd, int version, union semun arg)
+{
+	int err;
+	struct sem_array *sma;
+
+	switch(cmd) {
+	case IPC_INFO:
+	case SEM_INFO:
+	{
+		struct seminfo seminfo;
+		int max_id;
+
+		err = security_sem_semctl(NULL, cmd);
+		if (err)
+			return err;
+		
+		memset(&seminfo,0,sizeof(seminfo));
+		seminfo.semmni = ns->sc_semmni;
+		seminfo.semmns = ns->sc_semmns;
+		seminfo.semmsl = ns->sc_semmsl;
+		seminfo.semopm = ns->sc_semopm;
+		seminfo.semvmx = SEMVMX;
+		seminfo.semmnu = SEMMNU;
+		seminfo.semmap = SEMMAP;
+		seminfo.semume = SEMUME;
+		down_read(&sem_ids(ns).rw_mutex);
+		if (cmd == SEM_INFO) {
+			seminfo.semusz = sem_ids(ns).in_use;
+			seminfo.semaem = ns->used_sems;
+		} else {
+			seminfo.semusz = SEMUSZ;
+			seminfo.semaem = SEMAEM;
+		}
+		max_id = ipc_get_maxid(&sem_ids(ns));
+		up_read(&sem_ids(ns).rw_mutex);
+		if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) 
+			return -EFAULT;
+		return (max_id < 0) ? 0: max_id;
+	}
+	case IPC_STAT:
+	case SEM_STAT:
+	{
+		struct semid64_ds tbuf;
+		int id;
+
+		if (cmd == SEM_STAT) {
+			sma = sem_lock(ns, semid);
+			if (IS_ERR(sma))
+				return PTR_ERR(sma);
+			id = sma->sem_perm.id;
+		} else {
+			sma = sem_lock_check(ns, semid);
+			if (IS_ERR(sma))
+				return PTR_ERR(sma);
+			id = 0;
+		}
+
+		err = -EACCES;
+		if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
+			goto out_unlock;
+
+		err = security_sem_semctl(sma, cmd);
+		if (err)
+			goto out_unlock;
+
+		memset(&tbuf, 0, sizeof(tbuf));
+
+		kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
+		tbuf.sem_otime  = sma->sem_otime;
+		tbuf.sem_ctime  = sma->sem_ctime;
+		tbuf.sem_nsems  = sma->sem_nsems;
+		sem_unlock(sma);
+		if (copy_semid_to_user (arg.buf, &tbuf, version))
+			return -EFAULT;
+		return id;
+	}
+	default:
+		return -EINVAL;
+	}
+out_unlock:
+	sem_unlock(sma);
+	return err;
+}
+
+static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
+		int cmd, int version, union semun arg)
+{
+	struct sem_array *sma;
+	struct sem* curr;
+	int err;
+	ushort fast_sem_io[SEMMSL_FAST];
+	ushort* sem_io = fast_sem_io;
+	int nsems;
+	struct list_head tasks;
+
+	sma = sem_lock_check(ns, semid);
+	if (IS_ERR(sma))
+		return PTR_ERR(sma);
+
+	INIT_LIST_HEAD(&tasks);
+	nsems = sma->sem_nsems;
+
+	err = -EACCES;
+	if (ipcperms(ns, &sma->sem_perm,
+			(cmd == SETVAL || cmd == SETALL) ? S_IWUGO : S_IRUGO))
+		goto out_unlock;
+
+	err = security_sem_semctl(sma, cmd);
+	if (err)
+		goto out_unlock;
+
+	err = -EACCES;
+	switch (cmd) {
+	case GETALL:
+	{
+		ushort __user *array = arg.array;
+		int i;
+
+		if(nsems > SEMMSL_FAST) {
+			sem_getref_and_unlock(sma);
+
+			sem_io = ipc_alloc(sizeof(ushort)*nsems);
+			if(sem_io == NULL) {
+				sem_putref(sma);
+				return -ENOMEM;
+			}
+
+			sem_lock_and_putref(sma);
+			if (sma->sem_perm.deleted) {
+				sem_unlock(sma);
+				err = -EIDRM;
+				goto out_free;
+			}
+		}
+
+		for (i = 0; i < sma->sem_nsems; i++)
+			sem_io[i] = sma->sem_base[i].semval;
+		sem_unlock(sma);
+		err = 0;
+		if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
+			err = -EFAULT;
+		goto out_free;
+	}
+	case SETALL:
+	{
+		int i;
+		struct sem_undo *un;
+
+		sem_getref_and_unlock(sma);
+
+		if(nsems > SEMMSL_FAST) {
+			sem_io = ipc_alloc(sizeof(ushort)*nsems);
+			if(sem_io == NULL) {
+				sem_putref(sma);
+				return -ENOMEM;
+			}
+		}
+
+		if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
+			sem_putref(sma);
+			err = -EFAULT;
+			goto out_free;
+		}
+
+		for (i = 0; i < nsems; i++) {
+			if (sem_io[i] > SEMVMX) {
+				sem_putref(sma);
+				err = -ERANGE;
+				goto out_free;
+			}
+		}
+		sem_lock_and_putref(sma);
+		if (sma->sem_perm.deleted) {
+			sem_unlock(sma);
+			err = -EIDRM;
+			goto out_free;
+		}
+
+		for (i = 0; i < nsems; i++)
+			sma->sem_base[i].semval = sem_io[i];
+
+		assert_spin_locked(&sma->sem_perm.lock);
+		list_for_each_entry(un, &sma->list_id, list_id) {
+			for (i = 0; i < nsems; i++)
+				un->semadj[i] = 0;
+		}
+		sma->sem_ctime = get_seconds();
+		/* maybe some queued-up processes were waiting for this */
+		do_smart_update(sma, NULL, 0, 0, &tasks);
+		err = 0;
+		goto out_unlock;
+	}
+	/* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */
+	}
+	err = -EINVAL;
+	if(semnum < 0 || semnum >= nsems)
+		goto out_unlock;
+
+	curr = &sma->sem_base[semnum];
+
+	switch (cmd) {
+	case GETVAL:
+		err = curr->semval;
+		goto out_unlock;
+	case GETPID:
+		err = curr->sempid;
+		goto out_unlock;
+	case GETNCNT:
+		err = count_semncnt(sma,semnum);
+		goto out_unlock;
+	case GETZCNT:
+		err = count_semzcnt(sma,semnum);
+		goto out_unlock;
+	case SETVAL:
+	{
+		int val = arg.val;
+		struct sem_undo *un;
+
+		err = -ERANGE;
+		if (val > SEMVMX || val < 0)
+			goto out_unlock;
+
+		assert_spin_locked(&sma->sem_perm.lock);
+		list_for_each_entry(un, &sma->list_id, list_id)
+			un->semadj[semnum] = 0;
+
+		curr->semval = val;
+		curr->sempid = task_tgid_vnr(current);
+		sma->sem_ctime = get_seconds();
+		/* maybe some queued-up processes were waiting for this */
+		do_smart_update(sma, NULL, 0, 0, &tasks);
+		err = 0;
+		goto out_unlock;
+	}
+	}
+out_unlock:
+	sem_unlock(sma);
+	wake_up_sem_queue_do(&tasks);
+
+out_free:
+	if(sem_io != fast_sem_io)
+		ipc_free(sem_io, sizeof(ushort)*nsems);
+	return err;
+}
+
+static inline unsigned long
+copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version)
+{
+	switch(version) {
+	case IPC_64:
+		if (copy_from_user(out, buf, sizeof(*out)))
+			return -EFAULT;
+		return 0;
+	case IPC_OLD:
+	    {
+		struct semid_ds tbuf_old;
+
+		if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
+			return -EFAULT;
+
+		out->sem_perm.uid	= tbuf_old.sem_perm.uid;
+		out->sem_perm.gid	= tbuf_old.sem_perm.gid;
+		out->sem_perm.mode	= tbuf_old.sem_perm.mode;
+
+		return 0;
+	    }
+	default:
+		return -EINVAL;
+	}
+}
+
+/*
+ * This function handles some semctl commands which require the rw_mutex
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rw_mutex is taken inside this function.
+ */
+static int semctl_down(struct ipc_namespace *ns, int semid,
+		       int cmd, int version, union semun arg)
+{
+	struct sem_array *sma;
+	int err;
+	struct semid64_ds semid64;
+	struct kern_ipc_perm *ipcp;
+
+	if(cmd == IPC_SET) {
+		if (copy_semid_from_user(&semid64, arg.buf, version))
+			return -EFAULT;
+	}
+
+	ipcp = ipcctl_pre_down(ns, &sem_ids(ns), semid, cmd,
+			       &semid64.sem_perm, 0);
+	if (IS_ERR(ipcp))
+		return PTR_ERR(ipcp);
+
+	sma = container_of(ipcp, struct sem_array, sem_perm);
+
+	err = security_sem_semctl(sma, cmd);
+	if (err)
+		goto out_unlock;
+
+	switch(cmd){
+	case IPC_RMID:
+		freeary(ns, ipcp);
+		goto out_up;
+	case IPC_SET:
+		ipc_update_perm(&semid64.sem_perm, ipcp);
+		sma->sem_ctime = get_seconds();
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+out_unlock:
+	sem_unlock(sma);
+out_up:
+	up_write(&sem_ids(ns).rw_mutex);
+	return err;
+}
+
+SYSCALL_DEFINE(semctl)(int semid, int semnum, int cmd, union semun arg)
+{
+	int err = -EINVAL;
+	int version;
+	struct ipc_namespace *ns;
+
+	if (semid < 0)
+		return -EINVAL;
+
+	version = ipc_parse_version(&cmd);
+	ns = current->nsproxy->ipc_ns;
+
+	switch(cmd) {
+	case IPC_INFO:
+	case SEM_INFO:
+	case IPC_STAT:
+	case SEM_STAT:
+		err = semctl_nolock(ns, semid, cmd, version, arg);
+		return err;
+	case GETALL:
+	case GETVAL:
+	case GETPID:
+	case GETNCNT:
+	case GETZCNT:
+	case SETVAL:
+	case SETALL:
+		err = semctl_main(ns,semid,semnum,cmd,version,arg);
+		return err;
+	case IPC_RMID:
+	case IPC_SET:
+		err = semctl_down(ns, semid, cmd, version, arg);
+		return err;
+	default:
+		return -EINVAL;
+	}
+}
+#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
+asmlinkage long SyS_semctl(int semid, int semnum, int cmd, union semun arg)
+{
+	return SYSC_semctl((int) semid, (int) semnum, (int) cmd, arg);
+}
+SYSCALL_ALIAS(sys_semctl, SyS_semctl);
+#endif
+
+/* If the task doesn't already have a undo_list, then allocate one
+ * here.  We guarantee there is only one thread using this undo list,
+ * and current is THE ONE
+ *
+ * If this allocation and assignment succeeds, but later
+ * portions of this code fail, there is no need to free the sem_undo_list.
+ * Just let it stay associated with the task, and it'll be freed later
+ * at exit time.
+ *
+ * This can block, so callers must hold no locks.
+ */
+static inline int get_undo_list(struct sem_undo_list **undo_listp)
+{
+	struct sem_undo_list *undo_list;
+
+	undo_list = current->sysvsem.undo_list;
+	if (!undo_list) {
+		undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
+		if (undo_list == NULL)
+			return -ENOMEM;
+		spin_lock_init(&undo_list->lock);
+		atomic_set(&undo_list->refcnt, 1);
+		INIT_LIST_HEAD(&undo_list->list_proc);
+
+		current->sysvsem.undo_list = undo_list;
+	}
+	*undo_listp = undo_list;
+	return 0;
+}
+
+static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
+{
+	struct sem_undo *un;
+
+	list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
+		if (un->semid == semid)
+			return un;
+	}
+	return NULL;
+}
+
+static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
+{
+	struct sem_undo *un;
+
+  	assert_spin_locked(&ulp->lock);
+
+	un = __lookup_undo(ulp, semid);
+	if (un) {
+		list_del_rcu(&un->list_proc);
+		list_add_rcu(&un->list_proc, &ulp->list_proc);
+	}
+	return un;
+}
+
+/**
+ * find_alloc_undo - Lookup (and if not present create) undo array
+ * @ns: namespace
+ * @semid: semaphore array id
+ *
+ * The function looks up (and if not present creates) the undo structure.
+ * The size of the undo structure depends on the size of the semaphore
+ * array, thus the alloc path is not that straightforward.
+ * Lifetime-rules: sem_undo is rcu-protected, on success, the function
+ * performs a rcu_read_lock().
+ */
+static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
+{
+	struct sem_array *sma;
+	struct sem_undo_list *ulp;
+	struct sem_undo *un, *new;
+	int nsems;
+	int error;
+
+	error = get_undo_list(&ulp);
+	if (error)
+		return ERR_PTR(error);
+
+	rcu_read_lock();
+	spin_lock(&ulp->lock);
+	un = lookup_undo(ulp, semid);
+	spin_unlock(&ulp->lock);
+	if (likely(un!=NULL))
+		goto out;
+	rcu_read_unlock();
+
+	/* no undo structure around - allocate one. */
+	/* step 1: figure out the size of the semaphore array */
+	sma = sem_lock_check(ns, semid);
+	if (IS_ERR(sma))
+		return ERR_CAST(sma);
+
+	nsems = sma->sem_nsems;
+	sem_getref_and_unlock(sma);
+
+	/* step 2: allocate new undo structure */
+	new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
+	if (!new) {
+		sem_putref(sma);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* step 3: Acquire the lock on semaphore array */
+	sem_lock_and_putref(sma);
+	if (sma->sem_perm.deleted) {
+		sem_unlock(sma);
+		kfree(new);
+		un = ERR_PTR(-EIDRM);
+		goto out;
+	}
+	spin_lock(&ulp->lock);
+
+	/*
+	 * step 4: check for races: did someone else allocate the undo struct?
+	 */
+	un = lookup_undo(ulp, semid);
+	if (un) {
+		kfree(new);
+		goto success;
+	}
+	/* step 5: initialize & link new undo structure */
+	new->semadj = (short *) &new[1];
+	new->ulp = ulp;
+	new->semid = semid;
+	assert_spin_locked(&ulp->lock);
+	list_add_rcu(&new->list_proc, &ulp->list_proc);
+	assert_spin_locked(&sma->sem_perm.lock);
+	list_add(&new->list_id, &sma->list_id);
+	un = new;
+
+success:
+	spin_unlock(&ulp->lock);
+	rcu_read_lock();
+	sem_unlock(sma);
+out:
+	return un;
+}
+
+
+/**
+ * get_queue_result - Retrieve the result code from sem_queue
+ * @q: Pointer to queue structure
+ *
+ * Retrieve the return code from the pending queue. If IN_WAKEUP is found in
+ * q->status, then we must loop until the value is replaced with the final
+ * value: This may happen if a task is woken up by an unrelated event (e.g.
+ * signal) and in parallel the task is woken up by another task because it got
+ * the requested semaphores.
+ *
+ * The function can be called with or without holding the semaphore spinlock.
+ */
+static int get_queue_result(struct sem_queue *q)
+{
+	int error;
+
+	error = q->status;
+	while (unlikely(error == IN_WAKEUP)) {
+		cpu_relax();
+		error = q->status;
+	}
+
+	return error;
+}
+
+
+SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
+		unsigned, nsops, const struct timespec __user *, timeout)
+{
+	int error = -EINVAL;
+	struct sem_array *sma;
+	struct sembuf fast_sops[SEMOPM_FAST];
+	struct sembuf* sops = fast_sops, *sop;
+	struct sem_undo *un;
+	int undos = 0, alter = 0, max;
+	struct sem_queue queue;
+	unsigned long jiffies_left = 0;
+	struct ipc_namespace *ns;
+	struct list_head tasks;
+
+	ns = current->nsproxy->ipc_ns;
+
+	if (nsops < 1 || semid < 0)
+		return -EINVAL;
+	if (nsops > ns->sc_semopm)
+		return -E2BIG;
+	if(nsops > SEMOPM_FAST) {
+		sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL);
+		if(sops==NULL)
+			return -ENOMEM;
+	}
+	if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
+		error=-EFAULT;
+		goto out_free;
+	}
+	if (timeout) {
+		struct timespec _timeout;
+		if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
+			error = -EFAULT;
+			goto out_free;
+		}
+		if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
+			_timeout.tv_nsec >= 1000000000L) {
+			error = -EINVAL;
+			goto out_free;
+		}
+		jiffies_left = timespec_to_jiffies(&_timeout);
+	}
+	max = 0;
+	for (sop = sops; sop < sops + nsops; sop++) {
+		if (sop->sem_num >= max)
+			max = sop->sem_num;
+		if (sop->sem_flg & SEM_UNDO)
+			undos = 1;
+		if (sop->sem_op != 0)
+			alter = 1;
+	}
+
+	if (undos) {
+		un = find_alloc_undo(ns, semid);
+		if (IS_ERR(un)) {
+			error = PTR_ERR(un);
+			goto out_free;
+		}
+	} else
+		un = NULL;
+
+	INIT_LIST_HEAD(&tasks);
+
+	sma = sem_lock_check(ns, semid);
+	if (IS_ERR(sma)) {
+		if (un)
+			rcu_read_unlock();
+		error = PTR_ERR(sma);
+		goto out_free;
+	}
+
+	/*
+	 * semid identifiers are not unique - find_alloc_undo may have
+	 * allocated an undo structure, it was invalidated by an RMID
+	 * and now a new array with received the same id. Check and fail.
+	 * This case can be detected checking un->semid. The existence of
+	 * "un" itself is guaranteed by rcu.
+	 */
+	error = -EIDRM;
+	if (un) {
+		if (un->semid == -1) {
+			rcu_read_unlock();
+			goto out_unlock_free;
+		} else {
+			/*
+			 * rcu lock can be released, "un" cannot disappear:
+			 * - sem_lock is acquired, thus IPC_RMID is
+			 *   impossible.
+			 * - exit_sem is impossible, it always operates on
+			 *   current (or a dead task).
+			 */
+
+			rcu_read_unlock();
+		}
+	}
+
+	error = -EFBIG;
+	if (max >= sma->sem_nsems)
+		goto out_unlock_free;
+
+	error = -EACCES;
+	if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
+		goto out_unlock_free;
+
+	error = security_sem_semop(sma, sops, nsops, alter);
+	if (error)
+		goto out_unlock_free;
+
+	error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current));
+	if (error <= 0) {
+		if (alter && error == 0)
+			do_smart_update(sma, sops, nsops, 1, &tasks);
+
+		goto out_unlock_free;
+	}
+
+	/* We need to sleep on this operation, so we put the current
+	 * task into the pending queue and go to sleep.
+	 */
+		
+	queue.sops = sops;
+	queue.nsops = nsops;
+	queue.undo = un;
+	queue.pid = task_tgid_vnr(current);
+	queue.alter = alter;
+	if (alter)
+		list_add_tail(&queue.list, &sma->sem_pending);
+	else
+		list_add(&queue.list, &sma->sem_pending);
+
+	if (nsops == 1) {
+		struct sem *curr;
+		curr = &sma->sem_base[sops->sem_num];
+
+		if (alter)
+			list_add_tail(&queue.simple_list, &curr->sem_pending);
+		else
+			list_add(&queue.simple_list, &curr->sem_pending);
+	} else {
+		INIT_LIST_HEAD(&queue.simple_list);
+		sma->complex_count++;
+	}
+
+	queue.status = -EINTR;
+	queue.sleeper = current;
+	current->state = TASK_INTERRUPTIBLE;
+	sem_unlock(sma);
+
+	if (timeout)
+		jiffies_left = schedule_timeout(jiffies_left);
+	else
+		schedule();
+
+	error = get_queue_result(&queue);
+
+	if (error != -EINTR) {
+		/* fast path: update_queue already obtained all requested
+		 * resources.
+		 * Perform a smp_mb(): User space could assume that semop()
+		 * is a memory barrier: Without the mb(), the cpu could
+		 * speculatively read in user space stale data that was
+		 * overwritten by the previous owner of the semaphore.
+		 */
+		smp_mb();
+
+		goto out_free;
+	}
+
+	sma = sem_lock(ns, semid);
+
+	/*
+	 * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing.
+	 */
+	error = get_queue_result(&queue);
+
+	/*
+	 * Array removed? If yes, leave without sem_unlock().
+	 */
+	if (IS_ERR(sma)) {
+		error = -EIDRM;
+		goto out_free;
+	}
+
+
+	/*
+	 * If queue.status != -EINTR we are woken up by another process.
+	 * Leave without unlink_queue(), but with sem_unlock().
+	 */
+
+	if (error != -EINTR) {
+		goto out_unlock_free;
+	}
+
+	/*
+	 * If an interrupt occurred we have to clean up the queue
+	 */
+	if (timeout && jiffies_left == 0)
+		error = -EAGAIN;
+	unlink_queue(sma, &queue);
+
+out_unlock_free:
+	sem_unlock(sma);
+
+	wake_up_sem_queue_do(&tasks);
+out_free:
+	if(sops != fast_sops)
+		kfree(sops);
+	return error;
+}
+
+SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,
+		unsigned, nsops)
+{
+	return sys_semtimedop(semid, tsops, nsops, NULL);
+}
+
+/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
+ * parent and child tasks.
+ */
+
+int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
+{
+	struct sem_undo_list *undo_list;
+	int error;
+
+	if (clone_flags & CLONE_SYSVSEM) {
+		error = get_undo_list(&undo_list);
+		if (error)
+			return error;
+		atomic_inc(&undo_list->refcnt);
+		tsk->sysvsem.undo_list = undo_list;
+	} else 
+		tsk->sysvsem.undo_list = NULL;
+
+	return 0;
+}
+
+/*
+ * add semadj values to semaphores, free undo structures.
+ * undo structures are not freed when semaphore arrays are destroyed
+ * so some of them may be out of date.
+ * IMPLEMENTATION NOTE: There is some confusion over whether the
+ * set of adjustments that needs to be done should be done in an atomic
+ * manner or not. That is, if we are attempting to decrement the semval
+ * should we queue up and wait until we can do so legally?
+ * The original implementation attempted to do this (queue and wait).
+ * The current implementation does not do so. The POSIX standard
+ * and SVID should be consulted to determine what behavior is mandated.
+ */
+void exit_sem(struct task_struct *tsk)
+{
+	struct sem_undo_list *ulp;
+
+	ulp = tsk->sysvsem.undo_list;
+	if (!ulp)
+		return;
+	tsk->sysvsem.undo_list = NULL;
+
+	if (!atomic_dec_and_test(&ulp->refcnt))
+		return;
+
+	for (;;) {
+		struct sem_array *sma;
+		struct sem_undo *un;
+		struct list_head tasks;
+		int semid;
+		int i;
+
+		rcu_read_lock();
+		un = list_entry_rcu(ulp->list_proc.next,
+				    struct sem_undo, list_proc);
+		if (&un->list_proc == &ulp->list_proc)
+			semid = -1;
+		 else
+			semid = un->semid;
+		rcu_read_unlock();
+
+		if (semid == -1)
+			break;
+
+		sma = sem_lock_check(tsk->nsproxy->ipc_ns, un->semid);
+
+		/* exit_sem raced with IPC_RMID, nothing to do */
+		if (IS_ERR(sma))
+			continue;
+
+		un = __lookup_undo(ulp, semid);
+		if (un == NULL) {
+			/* exit_sem raced with IPC_RMID+semget() that created
+			 * exactly the same semid. Nothing to do.
+			 */
+			sem_unlock(sma);
+			continue;
+		}
+
+		/* remove un from the linked lists */
+		assert_spin_locked(&sma->sem_perm.lock);
+		list_del(&un->list_id);
+
+		spin_lock(&ulp->lock);
+		list_del_rcu(&un->list_proc);
+		spin_unlock(&ulp->lock);
+
+		/* perform adjustments registered in un */
+		for (i = 0; i < sma->sem_nsems; i++) {
+			struct sem * semaphore = &sma->sem_base[i];
+			if (un->semadj[i]) {
+				semaphore->semval += un->semadj[i];
+				/*
+				 * Range checks of the new semaphore value,
+				 * not defined by sus:
+				 * - Some unices ignore the undo entirely
+				 *   (e.g. HP UX 11i 11.22, Tru64 V5.1)
+				 * - some cap the value (e.g. FreeBSD caps
+				 *   at 0, but doesn't enforce SEMVMX)
+				 *
+				 * Linux caps the semaphore value, both at 0
+				 * and at SEMVMX.
+				 *
+				 * 	Manfred <manfred@colorfullife.com>
+				 */
+				if (semaphore->semval < 0)
+					semaphore->semval = 0;
+				if (semaphore->semval > SEMVMX)
+					semaphore->semval = SEMVMX;
+				semaphore->sempid = task_tgid_vnr(current);
+			}
+		}
+		/* maybe some queued-up processes were waiting for this */
+		INIT_LIST_HEAD(&tasks);
+		do_smart_update(sma, NULL, 0, 1, &tasks);
+		sem_unlock(sma);
+		wake_up_sem_queue_do(&tasks);
+
+		call_rcu(&un->rcu, free_un);
+	}
+	kfree(ulp);
+}
+
+#ifdef CONFIG_PROC_FS
+static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
+{
+	struct sem_array *sma = it;
+
+	return seq_printf(s,
+			  "%10d %10d  %4o %10u %5u %5u %5u %5u %10lu %10lu\n",
+			  sma->sem_perm.key,
+			  sma->sem_perm.id,
+			  sma->sem_perm.mode,
+			  sma->sem_nsems,
+			  sma->sem_perm.uid,
+			  sma->sem_perm.gid,
+			  sma->sem_perm.cuid,
+			  sma->sem_perm.cgid,
+			  sma->sem_otime,
+			  sma->sem_ctime);
+}
+#endif