[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/ipc/sem.c b/ap/os/linux/linux-3.4.x/ipc/sem.c
new file mode 100755
index 0000000..03fe705
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/ipc/sem.c
@@ -0,0 +1,1708 @@
+/*
+ * 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"
+
+/* One semaphore structure for each semaphore in the system. */
+struct sem {
+ int semval; /* current value */
+ int sempid; /* pid of last operation */
+ struct list_head sem_pending; /* pending single-sop operations */
+};
+
+/* One queue for each sleeping process in the system. */
+struct sem_queue {
+ struct list_head simple_list; /* queue of pending operations */
+ struct list_head list; /* queue of pending operations */
+ struct task_struct *sleeper; /* this process */
+ struct sem_undo *undo; /* undo structure */
+ int pid; /* process id of requesting process */
+ int status; /* completion status of operation */
+ struct sembuf *sops; /* array of pending operations */
+ int nsops; /* number of operations */
+ int alter; /* does *sops alter the array? */
+};
+
+/* Each task has a list of undo requests. They are executed automatically
+ * when the process exits.
+ */
+struct sem_undo {
+ struct list_head list_proc; /* per-process list: *
+ * all undos from one process
+ * rcu protected */
+ struct rcu_head rcu; /* rcu struct for sem_undo */
+ struct sem_undo_list *ulp; /* back ptr to sem_undo_list */
+ struct list_head list_id; /* per semaphore array list:
+ * all undos for one array */
+ int semid; /* semaphore set identifier */
+ short *semadj; /* array of adjustments */
+ /* one per semaphore */
+};
+
+/* sem_undo_list controls shared access to the list of sem_undo structures
+ * that may be shared among all a CLONE_SYSVSEM task group.
+ */
+struct sem_undo_list {
+ atomic_t refcnt;
+ spinlock_t lock;
+ struct list_head list_proc;
+};
+
+
+#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);
+ if (IS_ENABLED(CONFIG_PROC_STRIPPED))
+ return 0;
+
+ 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)
+{
+#ifdef CONFIG_PREEMPT_RT_BASE
+ struct task_struct *p = q->sleeper;
+ get_task_struct(p);
+ q->status = error;
+ wake_up_process(p);
+ put_task_struct(p);
+#else
+ 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);
+#endif
+}
+
+/**
+ * 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)
+{
+#ifndef CONFIG_PREEMPT_RT_BASE
+ 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();
+#endif
+}
+
+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;
+}
+
+/* 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);
+ kfree_rcu(un, rcu);
+ }
+
+ /* 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;
+
+sleep_again:
+ 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)) {
+ 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;
+
+ /*
+ * If the wakeup was spurious, just retry
+ */
+ if (error == -EINTR && !signal_pending(current))
+ goto sleep_again;
+
+ 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);
+
+ kfree_rcu(un, rcu);
+ }
+ 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