Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1384 insertions, 0 deletions

diff --git a/ipc/sem.c b/ipc/sem.c
new file mode 100644
index 000000000000..5ad7ac0ed60d
--- /dev/null
+++ b/ipc/sem.c
@@ -0,0 +1,1384 @@
+/*
+ * linux/ipc/sem.c
+ * Copyright (C) 1992 Krishna Balasubramanian
+ * Copyright (C) 1995 Eric Schenk, Bruno Haible
+ *
+ * IMPLEMENTATION NOTES ON CODE REWRITE (Eric Schenk, January 1995):
+ * This code underwent a massive rewrite in order to solve some problems
+ * with the original code. In particular the original code failed to
+ * wake up processes that were waiting for semval to go to 0 if the
+ * value went to 0 and was then incremented rapidly enough. In solving
+ * this problem I have also modified the implementation so that it
+ * processes pending operations in a FIFO manner, thus give a guarantee
+ * that processes waiting for a lock on the semaphore won't starve
+ * unless another locking process fails to unlock.
+ * In addition the following two changes in behavior have been introduced:
+ * - The original implementation of semop returned the value
+ *   last semaphore element examined on success. This does not
+ *   match the manual page specifications, and effectively
+ *   allows the user to read the semaphore even if they do not
+ *   have read permissions. The implementation now returns 0
+ *   on success as stated in the manual page.
+ * - There is some confusion over whether the set of undo adjustments
+ *   to be performed at exit should be done in an atomic manner.
+ *   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.
+ *   The current implementation does not do so. This is because I don't
+ *   think it is the right thing (TM) to do, and because I couldn't
+ *   see a clean way to get the old behavior with the new design.
+ *   The POSIX standard and SVID should be consulted to determine
+ *   what behavior is mandated.
+ *
+ * Further notes on refinement (Christoph Rohland, December 1998):
+ * - The POSIX standard says, that the undo adjustments simply should
+ *   redo. So the current implementation is o.K.
+ * - The previous code had two flaws:
+ *   1) It actively gave the semaphore to the next waiting process
+ *      sleeping on the semaphore. Since this process did not have the
+ *      cpu this led to many unnecessary context switches and bad
+ *      performance. Now we only check which process should be able to
+ *      get the semaphore and if this process wants to reduce some
+ *      semaphore value we simply wake it up without doing the
+ *      operation. So it has to try to get it later. Thus e.g. the
+ *      running process may reacquire the semaphore during the current
+ *      time slice. If it only waits for zero or increases the semaphore,
+ *      we do the operation in advance and wake it up.
+ *   2) It did not wake up all zero waiting processes. We try to do
+ *      better but only get the semops right which only wait for zero or
+ *      increase. If there are decrement operations in the operations
+ *      array we do the same as before.
+ *
+ * With the incarnation of O(1) scheduler, it becomes unnecessary to perform
+ * check/retry algorithm for waking up blocked processes as the new scheduler
+ * is better at handling thread switch than the old one.
+ *
+ * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
+ *
+ * SMP-threaded, sysctl's added
+ * (c) 1999 Manfred Spraul <manfreds@colorfullife.com>
+ * Enforced range limit on SEM_UNDO
+ * (c) 2001 Red Hat Inc <alan@redhat.com>
+ * Lockless wakeup
+ * (c) 2003 Manfred Spraul <manfred@colorfullife.com>
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/time.h>
+#include <linux/smp_lock.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <asm/uaccess.h>
+#include "util.h"
+
+
+#define sem_lock(id)	((struct sem_array*)ipc_lock(&sem_ids,id))
+#define sem_unlock(sma)	ipc_unlock(&(sma)->sem_perm)
+#define sem_rmid(id)	((struct sem_array*)ipc_rmid(&sem_ids,id))
+#define sem_checkid(sma, semid)	\
+	ipc_checkid(&sem_ids,&sma->sem_perm,semid)
+#define sem_buildid(id, seq) \
+	ipc_buildid(&sem_ids, id, seq)
+static struct ipc_ids sem_ids;
+
+static int newary (key_t, int, int);
+static void freeary (struct sem_array *sma, int id);
+#ifdef CONFIG_PROC_FS
+static int sysvipc_sem_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
+#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.
+ *	
+ */
+
+int sem_ctls[4] = {SEMMSL, SEMMNS, SEMOPM, SEMMNI};
+#define sc_semmsl	(sem_ctls[0])
+#define sc_semmns	(sem_ctls[1])
+#define sc_semopm	(sem_ctls[2])
+#define sc_semmni	(sem_ctls[3])
+
+static int used_sems;
+
+void __init sem_init (void)
+{
+	used_sems = 0;
+	ipc_init_ids(&sem_ids,sc_semmni);
+
+#ifdef CONFIG_PROC_FS
+	create_proc_read_entry("sysvipc/sem", 0, NULL, sysvipc_sem_read_proc, NULL);
+#endif
+}
+
+/*
+ * 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 semaphore 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
+
+static int newary (key_t key, int nsems, int semflg)
+{
+	int id;
+	int retval;
+	struct sem_array *sma;
+	int size;
+
+	if (!nsems)
+		return -EINVAL;
+	if (used_sems + nsems > 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, &sma->sem_perm, sc_semmni);
+	if(id == -1) {
+		security_sem_free(sma);
+		ipc_rcu_putref(sma);
+		return -ENOSPC;
+	}
+	used_sems += nsems;
+
+	sma->sem_base = (struct sem *) &sma[1];
+	/* sma->sem_pending = NULL; */
+	sma->sem_pending_last = &sma->sem_pending;
+	/* sma->undo = NULL; */
+	sma->sem_nsems = nsems;
+	sma->sem_ctime = get_seconds();
+	sem_unlock(sma);
+
+	return sem_buildid(id, sma->sem_perm.seq);
+}
+
+asmlinkage long sys_semget (key_t key, int nsems, int semflg)
+{
+	int id, err = -EINVAL;
+	struct sem_array *sma;
+
+	if (nsems < 0 || nsems > sc_semmsl)
+		return -EINVAL;
+	down(&sem_ids.sem);
+	
+	if (key == IPC_PRIVATE) {
+		err = newary(key, nsems, semflg);
+	} else if ((id = ipc_findkey(&sem_ids, key)) == -1) {  /* key not used */
+		if (!(semflg & IPC_CREAT))
+			err = -ENOENT;
+		else
+			err = newary(key, nsems, semflg);
+	} else if (semflg & IPC_CREAT && semflg & IPC_EXCL) {
+		err = -EEXIST;
+	} else {
+		sma = sem_lock(id);
+		if(sma==NULL)
+			BUG();
+		if (nsems > sma->sem_nsems)
+			err = -EINVAL;
+		else if (ipcperms(&sma->sem_perm, semflg))
+			err = -EACCES;
+		else {
+			int semid = sem_buildid(id, sma->sem_perm.seq);
+			err = security_sem_associate(sma, semflg);
+			if (!err)
+				err = semid;
+		}
+		sem_unlock(sma);
+	}
+
+	up(&sem_ids.sem);
+	return err;
+}
+
+/* Manage the doubly linked list sma->sem_pending as a FIFO:
+ * insert new queue elements at the tail sma->sem_pending_last.
+ */
+static inline void append_to_queue (struct sem_array * sma,
+				    struct sem_queue * q)
+{
+	*(q->prev = sma->sem_pending_last) = q;
+	*(sma->sem_pending_last = &q->next) = NULL;
+}
+
+static inline void prepend_to_queue (struct sem_array * sma,
+				     struct sem_queue * q)
+{
+	q->next = sma->sem_pending;
+	*(q->prev = &sma->sem_pending) = q;
+	if (q->next)
+		q->next->prev = &q->next;
+	else /* sma->sem_pending_last == &sma->sem_pending */
+		sma->sem_pending_last = &q->next;
+}
+
+static inline void remove_from_queue (struct sem_array * sma,
+				      struct sem_queue * q)
+{
+	*(q->prev) = q->next;
+	if (q->next)
+		q->next->prev = q->prev;
+	else /* sma->sem_pending_last == &q->next */
+		sma->sem_pending_last = q->prev;
+	q->prev = NULL; /* mark as removed */
+}
+
+/*
+ * 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--;
+	}
+	
+	sma->sem_otime = get_seconds();
+	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;
+}
+
+/* Go through the pending queue for the indicated semaphore
+ * looking for tasks that can be completed.
+ */
+static void update_queue (struct sem_array * sma)
+{
+	int error;
+	struct sem_queue * q;
+
+	q = sma->sem_pending;
+	while(q) {
+		error = try_atomic_semop(sma, q->sops, q->nsops,
+					 q->undo, q->pid);
+
+		/* Does q->sleeper still need to sleep? */
+		if (error <= 0) {
+			struct sem_queue *n;
+			remove_from_queue(sma,q);
+			q->status = IN_WAKEUP;
+			/*
+			 * Continue scanning. The next operation
+			 * that must be checked depends on the type of the
+			 * completed operation:
+			 * - if the operation modified the array, then
+			 *   restart from the head of the queue and
+			 *   check for threads that might be waiting
+			 *   for semaphore values to become 0.
+			 * - if the operation didn't modify the array,
+			 *   then just continue.
+			 */
+			if (q->alter)
+				n = sma->sem_pending;
+			else
+				n = q->next;
+			wake_up_process(q->sleeper);
+			/* hands-off: q will disappear immediately after
+			 * writing q->status.
+			 */
+			q->status = error;
+			q = n;
+		} else {
+			q = q->next;
+		}
+	}
+}
+
+/* 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;
+	for (q = sma->sem_pending; q; q = q->next) {
+		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;
+	for (q = sma->sem_pending; q; q = q->next) {
+		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.sem down and
+ * the spinlock for this semaphore set hold. sem_ids.sem remains locked
+ * on exit.
+ */
+static void freeary (struct sem_array *sma, int id)
+{
+	struct sem_undo *un;
+	struct sem_queue *q;
+	int size;
+
+	/* Invalidate the existing undo structures for this semaphore set.
+	 * (They will be freed without any further action in exit_sem()
+	 * or during the next semop.)
+	 */
+	for (un = sma->undo; un; un = un->id_next)
+		un->semid = -1;
+
+	/* Wake up all pending processes and let them fail with EIDRM. */
+	q = sma->sem_pending;
+	while(q) {
+		struct sem_queue *n;
+		/* lazy remove_from_queue: we are killing the whole queue */
+		q->prev = NULL;
+		n = q->next;
+		q->status = IN_WAKEUP;
+		wake_up_process(q->sleeper); /* doesn't sleep */
+		q->status = -EIDRM;	/* hands-off q */
+		q = n;
+	}
+
+	/* Remove the semaphore set from the ID array*/
+	sma = sem_rmid(id);
+	sem_unlock(sma);
+
+	used_sems -= sma->sem_nsems;
+	size = sizeof (*sma) + sma->sem_nsems * sizeof (struct sem);
+	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;
+
+		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(int semid, int semnum, int cmd, int version, union semun arg)
+{
+	int err = -EINVAL;
+	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 = sc_semmni;
+		seminfo.semmns = sc_semmns;
+		seminfo.semmsl = sc_semmsl;
+		seminfo.semopm = sc_semopm;
+		seminfo.semvmx = SEMVMX;
+		seminfo.semmnu = SEMMNU;
+		seminfo.semmap = SEMMAP;
+		seminfo.semume = SEMUME;
+		down(&sem_ids.sem);
+		if (cmd == SEM_INFO) {
+			seminfo.semusz = sem_ids.in_use;
+			seminfo.semaem = used_sems;
+		} else {
+			seminfo.semusz = SEMUSZ;
+			seminfo.semaem = SEMAEM;
+		}
+		max_id = sem_ids.max_id;
+		up(&sem_ids.sem);
+		if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) 
+			return -EFAULT;
+		return (max_id < 0) ? 0: max_id;
+	}
+	case SEM_STAT:
+	{
+		struct semid64_ds tbuf;
+		int id;
+
+		if(semid >= sem_ids.entries->size)
+			return -EINVAL;
+
+		memset(&tbuf,0,sizeof(tbuf));
+
+		sma = sem_lock(semid);
+		if(sma == NULL)
+			return -EINVAL;
+
+		err = -EACCES;
+		if (ipcperms (&sma->sem_perm, S_IRUGO))
+			goto out_unlock;
+
+		err = security_sem_semctl(sma, cmd);
+		if (err)
+			goto out_unlock;
+
+		id = sem_buildid(semid, sma->sem_perm.seq);
+
+		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;
+	}
+	return err;
+out_unlock:
+	sem_unlock(sma);
+	return err;
+}
+
+static int semctl_main(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;
+
+	sma = sem_lock(semid);
+	if(sma==NULL)
+		return -EINVAL;
+
+	nsems = sma->sem_nsems;
+
+	err=-EIDRM;
+	if (sem_checkid(sma,semid))
+		goto out_unlock;
+
+	err = -EACCES;
+	if (ipcperms (&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) {
+			ipc_rcu_getref(sma);
+			sem_unlock(sma);			
+
+			sem_io = ipc_alloc(sizeof(ushort)*nsems);
+			if(sem_io == NULL) {
+				ipc_lock_by_ptr(&sma->sem_perm);
+				ipc_rcu_putref(sma);
+				sem_unlock(sma);
+				return -ENOMEM;
+			}
+
+			ipc_lock_by_ptr(&sma->sem_perm);
+			ipc_rcu_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;
+
+		ipc_rcu_getref(sma);
+		sem_unlock(sma);
+
+		if(nsems > SEMMSL_FAST) {
+			sem_io = ipc_alloc(sizeof(ushort)*nsems);
+			if(sem_io == NULL) {
+				ipc_lock_by_ptr(&sma->sem_perm);
+				ipc_rcu_putref(sma);
+				sem_unlock(sma);
+				return -ENOMEM;
+			}
+		}
+
+		if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
+			ipc_lock_by_ptr(&sma->sem_perm);
+			ipc_rcu_putref(sma);
+			sem_unlock(sma);
+			err = -EFAULT;
+			goto out_free;
+		}
+
+		for (i = 0; i < nsems; i++) {
+			if (sem_io[i] > SEMVMX) {
+				ipc_lock_by_ptr(&sma->sem_perm);
+				ipc_rcu_putref(sma);
+				sem_unlock(sma);
+				err = -ERANGE;
+				goto out_free;
+			}
+		}
+		ipc_lock_by_ptr(&sma->sem_perm);
+		ipc_rcu_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];
+		for (un = sma->undo; un; un = un->id_next)
+			for (i = 0; i < nsems; i++)
+				un->semadj[i] = 0;
+		sma->sem_ctime = get_seconds();
+		/* maybe some queued-up processes were waiting for this */
+		update_queue(sma);
+		err = 0;
+		goto out_unlock;
+	}
+	case IPC_STAT:
+	{
+		struct semid64_ds tbuf;
+		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 0;
+	}
+	/* 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;
+
+		for (un = sma->undo; un; un = un->id_next)
+			un->semadj[semnum] = 0;
+		curr->semval = val;
+		curr->sempid = current->tgid;
+		sma->sem_ctime = get_seconds();
+		/* maybe some queued-up processes were waiting for this */
+		update_queue(sma);
+		err = 0;
+		goto out_unlock;
+	}
+	}
+out_unlock:
+	sem_unlock(sma);
+out_free:
+	if(sem_io != fast_sem_io)
+		ipc_free(sem_io, sizeof(ushort)*nsems);
+	return err;
+}
+
+struct sem_setbuf {
+	uid_t	uid;
+	gid_t	gid;
+	mode_t	mode;
+};
+
+static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __user *buf, int version)
+{
+	switch(version) {
+	case IPC_64:
+	    {
+		struct semid64_ds tbuf;
+
+		if(copy_from_user(&tbuf, buf, sizeof(tbuf)))
+			return -EFAULT;
+
+		out->uid	= tbuf.sem_perm.uid;
+		out->gid	= tbuf.sem_perm.gid;
+		out->mode	= tbuf.sem_perm.mode;
+
+		return 0;
+	    }
+	case IPC_OLD:
+	    {
+		struct semid_ds tbuf_old;
+
+		if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
+			return -EFAULT;
+
+		out->uid	= tbuf_old.sem_perm.uid;
+		out->gid	= tbuf_old.sem_perm.gid;
+		out->mode	= tbuf_old.sem_perm.mode;
+
+		return 0;
+	    }
+	default:
+		return -EINVAL;
+	}
+}
+
+static int semctl_down(int semid, int semnum, int cmd, int version, union semun arg)
+{
+	struct sem_array *sma;
+	int err;
+	struct sem_setbuf setbuf;
+	struct kern_ipc_perm *ipcp;
+
+	if(cmd == IPC_SET) {
+		if(copy_semid_from_user (&setbuf, arg.buf, version))
+			return -EFAULT;
+		if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode)))
+			return err;
+	}
+	sma = sem_lock(semid);
+	if(sma==NULL)
+		return -EINVAL;
+
+	if (sem_checkid(sma,semid)) {
+		err=-EIDRM;
+		goto out_unlock;
+	}	
+	ipcp = &sma->sem_perm;
+	
+	if (current->euid != ipcp->cuid && 
+	    current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) {
+	    	err=-EPERM;
+		goto out_unlock;
+	}
+
+	err = security_sem_semctl(sma, cmd);
+	if (err)
+		goto out_unlock;
+
+	switch(cmd){
+	case IPC_RMID:
+		freeary(sma, semid);
+		err = 0;
+		break;
+	case IPC_SET:
+		ipcp->uid = setbuf.uid;
+		ipcp->gid = setbuf.gid;
+		ipcp->mode = (ipcp->mode & ~S_IRWXUGO)
+				| (setbuf.mode & S_IRWXUGO);
+		sma->sem_ctime = get_seconds();
+		sem_unlock(sma);
+		err = 0;
+		break;
+	default:
+		sem_unlock(sma);
+		err = -EINVAL;
+		break;
+	}
+	return err;
+
+out_unlock:
+	sem_unlock(sma);
+	return err;
+}
+
+asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
+{
+	int err = -EINVAL;
+	int version;
+
+	if (semid < 0)
+		return -EINVAL;
+
+	version = ipc_parse_version(&cmd);
+
+	switch(cmd) {
+	case IPC_INFO:
+	case SEM_INFO:
+	case SEM_STAT:
+		err = semctl_nolock(semid,semnum,cmd,version,arg);
+		return err;
+	case GETALL:
+	case GETVAL:
+	case GETPID:
+	case GETNCNT:
+	case GETZCNT:
+	case IPC_STAT:
+	case SETVAL:
+	case SETALL:
+		err = semctl_main(semid,semnum,cmd,version,arg);
+		return err;
+	case IPC_RMID:
+	case IPC_SET:
+		down(&sem_ids.sem);
+		err = semctl_down(semid,semnum,cmd,version,arg);
+		up(&sem_ids.sem);
+		return err;
+	default:
+		return -EINVAL;
+	}
+}
+
+static inline void lock_semundo(void)
+{
+	struct sem_undo_list *undo_list;
+
+	undo_list = current->sysvsem.undo_list;
+	if ((undo_list != NULL) && (atomic_read(&undo_list->refcnt) != 1))
+		spin_lock(&undo_list->lock);
+}
+
+/* This code has an interaction with copy_semundo().
+ * Consider; two tasks are sharing the undo_list. task1
+ * acquires the undo_list lock in lock_semundo().  If task2 now
+ * exits before task1 releases the lock (by calling
+ * unlock_semundo()), then task1 will never call spin_unlock().
+ * This leave the sem_undo_list in a locked state.  If task1 now creats task3
+ * and once again shares the sem_undo_list, the sem_undo_list will still be
+ * locked, and future SEM_UNDO operations will deadlock.  This case is
+ * dealt with in copy_semundo() by having it reinitialize the spin lock when 
+ * the refcnt goes from 1 to 2.
+ */
+static inline void unlock_semundo(void)
+{
+	struct sem_undo_list *undo_list;
+
+	undo_list = current->sysvsem.undo_list;
+	if ((undo_list != NULL) && (atomic_read(&undo_list->refcnt) != 1))
+		spin_unlock(&undo_list->lock);
+}
+
+
+/* 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;
+	int size;
+
+	undo_list = current->sysvsem.undo_list;
+	if (!undo_list) {
+		size = sizeof(struct sem_undo_list);
+		undo_list = (struct sem_undo_list *) kmalloc(size, GFP_KERNEL);
+		if (undo_list == NULL)
+			return -ENOMEM;
+		memset(undo_list, 0, size);
+		/* don't initialize unodhd->lock here.  It's done
+		 * in copy_semundo() instead.
+		 */
+		atomic_set(&undo_list->refcnt, 1);
+		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 **last, *un;
+
+	last = &ulp->proc_list;
+	un = *last;
+	while(un != NULL) {
+		if(un->semid==semid)
+			break;
+		if(un->semid==-1) {
+			*last=un->proc_next;
+			kfree(un);
+		} else {
+			last=&un->proc_next;
+		}
+		un=*last;
+	}
+	return un;
+}
+
+static struct sem_undo *find_undo(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);
+
+	lock_semundo();
+	un = lookup_undo(ulp, semid);
+	unlock_semundo();
+	if (likely(un!=NULL))
+		goto out;
+
+	/* no undo structure around - allocate one. */
+	sma = sem_lock(semid);
+	un = ERR_PTR(-EINVAL);
+	if(sma==NULL)
+		goto out;
+	un = ERR_PTR(-EIDRM);
+	if (sem_checkid(sma,semid)) {
+		sem_unlock(sma);
+		goto out;
+	}
+	nsems = sma->sem_nsems;
+	ipc_rcu_getref(sma);
+	sem_unlock(sma);
+
+	new = (struct sem_undo *) kmalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
+	if (!new) {
+		ipc_lock_by_ptr(&sma->sem_perm);
+		ipc_rcu_putref(sma);
+		sem_unlock(sma);
+		return ERR_PTR(-ENOMEM);
+	}
+	memset(new, 0, sizeof(struct sem_undo) + sizeof(short)*nsems);
+	new->semadj = (short *) &new[1];
+	new->semid = semid;
+
+	lock_semundo();
+	un = lookup_undo(ulp, semid);
+	if (un) {
+		unlock_semundo();
+		kfree(new);
+		ipc_lock_by_ptr(&sma->sem_perm);
+		ipc_rcu_putref(sma);
+		sem_unlock(sma);
+		goto out;
+	}
+	ipc_lock_by_ptr(&sma->sem_perm);
+	ipc_rcu_putref(sma);
+	if (sma->sem_perm.deleted) {
+		sem_unlock(sma);
+		unlock_semundo();
+		kfree(new);
+		un = ERR_PTR(-EIDRM);
+		goto out;
+	}
+	new->proc_next = ulp->proc_list;
+	ulp->proc_list = new;
+	new->id_next = sma->undo;
+	sma->undo = new;
+	sem_unlock(sma);
+	un = new;
+	unlock_semundo();
+out:
+	return un;
+}
+
+asmlinkage long sys_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, decrease = 0, alter = 0, max;
+	struct sem_queue queue;
+	unsigned long jiffies_left = 0;
+
+	if (nsops < 1 || semid < 0)
+		return -EINVAL;
+	if (nsops > 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++;
+		if (sop->sem_op < 0)
+			decrease = 1;
+		if (sop->sem_op > 0)
+			alter = 1;
+	}
+	alter |= decrease;
+
+retry_undos:
+	if (undos) {
+		un = find_undo(semid);
+		if (IS_ERR(un)) {
+			error = PTR_ERR(un);
+			goto out_free;
+		}
+	} else
+		un = NULL;
+
+	sma = sem_lock(semid);
+	error=-EINVAL;
+	if(sma==NULL)
+		goto out_free;
+	error = -EIDRM;
+	if (sem_checkid(sma,semid))
+		goto out_unlock_free;
+	/*
+	 * semid identifies are not unique - find_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 retry.
+	 */
+	if (un && un->semid == -1) {
+		sem_unlock(sma);
+		goto retry_undos;
+	}
+	error = -EFBIG;
+	if (max >= sma->sem_nsems)
+		goto out_unlock_free;
+
+	error = -EACCES;
+	if (ipcperms(&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, current->tgid);
+	if (error <= 0) {
+		if (alter && error == 0)
+			update_queue (sma);
+		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.sma = sma;
+	queue.sops = sops;
+	queue.nsops = nsops;
+	queue.undo = un;
+	queue.pid = current->tgid;
+	queue.id = semid;
+	queue.alter = alter;
+	if (alter)
+		append_to_queue(sma ,&queue);
+	else
+		prepend_to_queue(sma ,&queue);
+
+	queue.status = -EINTR;
+	queue.sleeper = current;
+	current->state = TASK_INTERRUPTIBLE;
+	sem_unlock(sma);
+
+	if (timeout)
+		jiffies_left = schedule_timeout(jiffies_left);
+	else
+		schedule();
+
+	error = queue.status;
+	while(unlikely(error == IN_WAKEUP)) {
+		cpu_relax();
+		error = queue.status;
+	}
+
+	if (error != -EINTR) {
+		/* fast path: update_queue already obtained all requested
+		 * resources */
+		goto out_free;
+	}
+
+	sma = sem_lock(semid);
+	if(sma==NULL) {
+		if(queue.prev != NULL)
+			BUG();
+		error = -EIDRM;
+		goto out_free;
+	}
+
+	/*
+	 * If queue.status != -EINTR we are woken up by another process
+	 */
+	error = queue.status;
+	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;
+	remove_from_queue(sma,&queue);
+	goto out_unlock_free;
+
+out_unlock_free:
+	sem_unlock(sma);
+out_free:
+	if(sops != fast_sops)
+		kfree(sops);
+	return error;
+}
+
+asmlinkage long sys_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.
+ *
+ * See the notes above unlock_semundo() regarding the spin_lock_init()
+ * in this code.  Initialize the undo_list->lock here instead of get_undo_list()
+ * because of the reasoning in the comment above unlock_semundo.
+ */
+
+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;
+		if (atomic_read(&undo_list->refcnt) == 1)
+			spin_lock_init(&undo_list->lock);
+		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 *undo_list;
+	struct sem_undo *u, **up;
+
+	undo_list = tsk->sysvsem.undo_list;
+	if (!undo_list)
+		return;
+
+	if (!atomic_dec_and_test(&undo_list->refcnt))
+		return;
+
+	/* There's no need to hold the semundo list lock, as current
+         * is the last task exiting for this undo list.
+	 */
+	for (up = &undo_list->proc_list; (u = *up); *up = u->proc_next, kfree(u)) {
+		struct sem_array *sma;
+		int nsems, i;
+		struct sem_undo *un, **unp;
+		int semid;
+	       
+		semid = u->semid;
+
+		if(semid == -1)
+			continue;
+		sma = sem_lock(semid);
+		if (sma == NULL)
+			continue;
+
+		if (u->semid == -1)
+			goto next_entry;
+
+		BUG_ON(sem_checkid(sma,u->semid));
+
+		/* remove u from the sma->undo list */
+		for (unp = &sma->undo; (un = *unp); unp = &un->id_next) {
+			if (u == un)
+				goto found;
+		}
+		printk ("exit_sem undo list error id=%d\n", u->semid);
+		goto next_entry;
+found:
+		*unp = un->id_next;
+		/* perform adjustments registered in u */
+		nsems = sma->sem_nsems;
+		for (i = 0; i < nsems; i++) {
+			struct sem * sem = &sma->sem_base[i];
+			if (u->semadj[i]) {
+				sem->semval += u->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 (sem->semval < 0)
+					sem->semval = 0;
+				if (sem->semval > SEMVMX)
+					sem->semval = SEMVMX;
+				sem->sempid = current->tgid;
+			}
+		}
+		sma->sem_otime = get_seconds();
+		/* maybe some queued-up processes were waiting for this */
+		update_queue(sma);
+next_entry:
+		sem_unlock(sma);
+	}
+	kfree(undo_list);
+}
+
+#ifdef CONFIG_PROC_FS
+static int sysvipc_sem_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
+{
+	off_t pos = 0;
+	off_t begin = 0;
+	int i, len = 0;
+
+	len += sprintf(buffer, "       key      semid perms      nsems   uid   gid  cuid  cgid      otime      ctime\n");
+	down(&sem_ids.sem);
+
+	for(i = 0; i <= sem_ids.max_id; i++) {
+		struct sem_array *sma;
+		sma = sem_lock(i);
+		if(sma) {
+			len += sprintf(buffer + len, "%10d %10d  %4o %10lu %5u %5u %5u %5u %10lu %10lu\n",
+				sma->sem_perm.key,
+				sem_buildid(i,sma->sem_perm.seq),
+				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);
+			sem_unlock(sma);
+
+			pos += len;
+			if(pos < offset) {
+				len = 0;
+	    			begin = pos;
+			}
+			if(pos > offset + length)
+				goto done;
+		}
+	}
+	*eof = 1;
+done:
+	up(&sem_ids.sem);
+	*start = buffer + (offset - begin);
+	len -= (offset - begin);
+	if(len > length)
+		len = length;
+	if(len < 0)
+		len = 0;
+	return len;
+}
+#endif