Merge branch 'linus' into x86/header-guards

Conflicts:

	include/asm-x86/gpio.h
	include/asm-x86/ide.h

Signed-off-by: Ingo Molnar <mingo@elte.hu>

7 files changed, 260 insertions, 264 deletions

diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index d3497465cc0..69bc85978ba 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -27,15 +27,17 @@ static void *get_ipc(ctl_table *table)
 }
 
 /*
- * Routine that is called when a tunable has successfully been changed by
- * hand and it has a callback routine registered on the ipc namespace notifier
- * chain: we don't want such tunables to be recomputed anymore upon memory
- * add/remove or ipc namespace creation/removal.
- * They can come back to a recomputable state by being set to a <0 value.
+ * Routine that is called when the file "auto_msgmni" has successfully been
+ * written.
+ * Two values are allowed:
+ * 0: unregister msgmni's callback routine from the ipc namespace notifier
+ *    chain. This means that msgmni won't be recomputed anymore upon memory
+ *    add/remove or ipc namespace creation/removal.
+ * 1: register back the callback routine.
  */
-static void tunable_set_callback(int val)
+static void ipc_auto_callback(int val)
 {
-	if (val >= 0)
+	if (!val)
 		unregister_ipcns_notifier(current->nsproxy->ipc_ns);
 	else {
 		/*
@@ -71,7 +73,12 @@ static int proc_ipc_callback_dointvec(ctl_table *table, int write,
 	rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
 
 	if (write && !rc && lenp_bef == *lenp)
-		tunable_set_callback(*((int *)(ipc_table.data)));
+		/*
+		 * Tunable has successfully been changed by hand. Disable its
+		 * automatic adjustment. This simply requires unregistering
+		 * the notifiers that trigger recalculation.
+		 */
+		unregister_ipcns_notifier(current->nsproxy->ipc_ns);
 
 	return rc;
 }
@@ -87,10 +94,39 @@ static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
 					lenp, ppos);
 }
 
+static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
+	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct ctl_table ipc_table;
+	size_t lenp_bef = *lenp;
+	int oldval;
+	int rc;
+
+	memcpy(&ipc_table, table, sizeof(ipc_table));
+	ipc_table.data = get_ipc(table);
+	oldval = *((int *)(ipc_table.data));
+
+	rc = proc_dointvec_minmax(&ipc_table, write, filp, buffer, lenp, ppos);
+
+	if (write && !rc && lenp_bef == *lenp) {
+		int newval = *((int *)(ipc_table.data));
+		/*
+		 * The file "auto_msgmni" has correctly been set.
+		 * React by (un)registering the corresponding tunable, if the
+		 * value has changed.
+		 */
+		if (newval != oldval)
+			ipc_auto_callback(newval);
+	}
+
+	return rc;
+}
+
 #else
 #define proc_ipc_doulongvec_minmax NULL
 #define proc_ipc_dointvec	   NULL
 #define proc_ipc_callback_dointvec NULL
+#define proc_ipcauto_dointvec_minmax NULL
 #endif
 
 #ifdef CONFIG_SYSCTL_SYSCALL
@@ -142,14 +178,11 @@ static int sysctl_ipc_registered_data(ctl_table *table, int __user *name,
 	rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval,
 		newlen);
 
-	if (newval && newlen && rc > 0) {
+	if (newval && newlen && rc > 0)
 		/*
 		 * Tunable has successfully been changed from userland
 		 */
-		int *data = get_ipc(table);
-
-		tunable_set_callback(*data);
-	}
+		unregister_ipcns_notifier(current->nsproxy->ipc_ns);
 
 	return rc;
 }
@@ -158,6 +191,9 @@ static int sysctl_ipc_registered_data(ctl_table *table, int __user *name,
 #define sysctl_ipc_registered_data NULL
 #endif
 
+static int zero;
+static int one = 1;
+
 static struct ctl_table ipc_kern_table[] = {
 	{
 		.ctl_name	= KERN_SHMMAX,
@@ -222,6 +258,16 @@ static struct ctl_table ipc_kern_table[] = {
 		.proc_handler	= proc_ipc_dointvec,
 		.strategy	= sysctl_ipc_data,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "auto_msgmni",
+		.data		= &init_ipc_ns.auto_msgmni,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_ipcauto_dointvec_minmax,
+		.extra1		= &zero,
+		.extra2		= &one,
+	},
 	{}
 };
 
diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c
index 70ff09183f7..b9b31a4f77e 100644
--- a/ipc/ipcns_notifier.c
+++ b/ipc/ipcns_notifier.c
@@ -55,25 +55,35 @@ static int ipcns_callback(struct notifier_block *self,
 
 int register_ipcns_notifier(struct ipc_namespace *ns)
 {
+	int rc;
+
 	memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
 	ns->ipcns_nb.notifier_call = ipcns_callback;
 	ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
-	return blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);
+	rc = blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);
+	if (!rc)
+		ns->auto_msgmni = 1;
+	return rc;
 }
 
 int cond_register_ipcns_notifier(struct ipc_namespace *ns)
 {
+	int rc;
+
 	memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
 	ns->ipcns_nb.notifier_call = ipcns_callback;
 	ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
-	return blocking_notifier_chain_cond_register(&ipcns_chain,
+	rc = blocking_notifier_chain_cond_register(&ipcns_chain,
 							&ns->ipcns_nb);
+	if (!rc)
+		ns->auto_msgmni = 1;
+	return rc;
 }
 
-int unregister_ipcns_notifier(struct ipc_namespace *ns)
+void unregister_ipcns_notifier(struct ipc_namespace *ns)
 {
-	return blocking_notifier_chain_unregister(&ipcns_chain,
-						&ns->ipcns_nb);
+	blocking_notifier_chain_unregister(&ipcns_chain, &ns->ipcns_nb);
+	ns->auto_msgmni = 0;
 }
 
 int ipcns_notify(unsigned long val)
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 3e84b958186..1fdc2eb2f6d 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -314,15 +314,11 @@ static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 *	through std routines)
 */
 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
-				size_t count, loff_t * off)
+				size_t count, loff_t *off)
 {
 	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
 	char buffer[FILENT_SIZE];
-	size_t slen;
-	loff_t o;
-
-	if (!count)
-		return 0;
+	ssize_t ret;
 
 	spin_lock(&info->lock);
 	snprintf(buffer, sizeof(buffer),
@@ -335,21 +331,14 @@ static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
 			pid_vnr(info->notify_owner));
 	spin_unlock(&info->lock);
 	buffer[sizeof(buffer)-1] = '\0';
-	slen = strlen(buffer)+1;
-
-	o = *off;
-	if (o > slen)
-		return 0;
-
-	if (o + count > slen)
-		count = slen - o;
 
-	if (copy_to_user(u_data, buffer + o, count))
-		return -EFAULT;
+	ret = simple_read_from_buffer(u_data, count, off, buffer,
+				strlen(buffer));
+	if (ret <= 0)
+		return ret;
 
-	*off = o + count;
 	filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
-	return count;
+	return ret;
 }
 
 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
diff --git a/ipc/sem.c b/ipc/sem.c
index e9418df5ff3..bf1bc36cb7e 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -272,9 +272,8 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
 	ns->used_sems += nsems;
 
 	sma->sem_base = (struct sem *) &sma[1];
-	/* sma->sem_pending = NULL; */
-	sma->sem_pending_last = &sma->sem_pending;
-	/* sma->undo = NULL; */
+	INIT_LIST_HEAD(&sma->sem_pending);
+	INIT_LIST_HEAD(&sma->list_id);
 	sma->sem_nsems = nsems;
 	sma->sem_ctime = get_seconds();
 	sem_unlock(sma);
@@ -331,38 +330,6 @@ asmlinkage long sys_semget(key_t key, int nsems, int semflg)
 	return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
 }
 
-/* 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.
@@ -438,16 +405,15 @@ static void update_queue (struct sem_array * sma)
 	int error;
 	struct sem_queue * q;
 
-	q = sma->sem_pending;
-	while(q) {
+	q = list_entry(sma->sem_pending.next, struct sem_queue, list);
+	while (&q->list != &sma->sem_pending) {
 		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
@@ -458,11 +424,26 @@ static void update_queue (struct sem_array * sma)
 			 *   for semaphore values to become 0.
 			 * - if the operation didn't modify the array,
 			 *   then just continue.
+			 * The order of list_del() and reading ->next
+			 * is crucial: In the former case, the list_del()
+			 * must be done first [because we might be the
+			 * first entry in ->sem_pending], in the latter
+			 * case the list_del() must be done last
+			 * [because the list is invalid after the list_del()]
 			 */
-			if (q->alter)
-				n = sma->sem_pending;
-			else
-				n = q->next;
+			if (q->alter) {
+				list_del(&q->list);
+				n = list_entry(sma->sem_pending.next,
+						struct sem_queue, list);
+			} else {
+				n = list_entry(q->list.next, struct sem_queue,
+						list);
+				list_del(&q->list);
+			}
+
+			/* wake up the waiting thread */
+			q->status = IN_WAKEUP;
+
 			wake_up_process(q->sleeper);
 			/* hands-off: q will disappear immediately after
 			 * writing q->status.
@@ -471,7 +452,7 @@ static void update_queue (struct sem_array * sma)
 			q->status = error;
 			q = n;
 		} else {
-			q = q->next;
+			q = list_entry(q->list.next, struct sem_queue, list);
 		}
 	}
 }
@@ -491,7 +472,7 @@ static int count_semncnt (struct sem_array * sma, ushort semnum)
 	struct sem_queue * q;
 
 	semncnt = 0;
-	for (q = sma->sem_pending; q; q = q->next) {
+	list_for_each_entry(q, &sma->sem_pending, list) {
 		struct sembuf * sops = q->sops;
 		int nsops = q->nsops;
 		int i;
@@ -503,13 +484,14 @@ static int count_semncnt (struct sem_array * sma, ushort semnum)
 	}
 	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) {
+	list_for_each_entry(q, &sma->sem_pending, list) {
 		struct sembuf * sops = q->sops;
 		int nsops = q->nsops;
 		int i;
@@ -522,35 +504,41 @@ static int count_semzcnt (struct sem_array * sma, ushort semnum)
 	return semzcnt;
 }
 
+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;
-	struct sem_queue *q;
+	struct sem_undo *un, *tu;
+	struct sem_queue *q, *tq;
 	struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
 
-	/* 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)
+	/* 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. */
-	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;
+	list_for_each_entry_safe(q, tq, &sma->sem_pending, list) {
+		list_del(&q->list);
+
 		q->status = IN_WAKEUP;
 		wake_up_process(q->sleeper); /* doesn't sleep */
 		smp_wmb();
 		q->status = -EIDRM;	/* hands-off q */
-		q = n;
 	}
 
 	/* Remove the semaphore set from the IDR */
@@ -763,9 +751,12 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 
 		for (i = 0; i < nsems; i++)
 			sma->sem_base[i].semval = sem_io[i];
-		for (un = sma->undo; un; un = un->id_next)
+
+		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 */
 		update_queue(sma);
@@ -797,12 +788,15 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 	{
 		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)
+		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();
@@ -952,6 +946,8 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp)
 			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;
@@ -960,25 +956,27 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp)
 
 static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
 {
-	struct sem_undo **last, *un;
+	struct sem_undo *walk;
 
-	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;
+	list_for_each_entry_rcu(walk, &ulp->list_proc, list_proc) {
+		if (walk->semid == semid)
+			return walk;
 	}
-	return un;
+	return NULL;
 }
 
-static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
+/**
+ * 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;
@@ -990,13 +988,16 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
 	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_PTR(PTR_ERR(sma));
@@ -1004,37 +1005,45 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
 	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);
 	}
-	new->semadj = (short *) &new[1];
-	new->semid = semid;
 
-	spin_lock(&ulp->lock);
-	un = lookup_undo(ulp, semid);
-	if (un) {
-		spin_unlock(&ulp->lock);
-		kfree(new);
-		sem_putref(sma);
-		goto out;
-	}
+	/* step 3: Acquire the lock on semaphore array */
 	sem_lock_and_putref(sma);
 	if (sma->sem_perm.deleted) {
 		sem_unlock(sma);
-		spin_unlock(&ulp->lock);
 		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);
+	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;
 }
@@ -1090,9 +1099,8 @@ asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops,
 			alter = 1;
 	}
 
-retry_undos:
 	if (undos) {
-		un = find_undo(ns, semid);
+		un = find_alloc_undo(ns, semid);
 		if (IS_ERR(un)) {
 			error = PTR_ERR(un);
 			goto out_free;
@@ -1102,19 +1110,37 @@ retry_undos:
 
 	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_undo may have
+	 * 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 retry.
+	 * and now a new array with received the same id. Check and fail.
+	 * This case can be detected checking un->semid. The existance of
+	 * "un" itself is guaranteed by rcu.
 	 */
-	if (un && un->semid == -1) {
-		sem_unlock(sma);
-		goto retry_undos;
+	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;
@@ -1138,17 +1164,15 @@ retry_undos:
 	 * task into the pending queue and go to sleep.
 	 */
 		
-	queue.sma = sma;
 	queue.sops = sops;
 	queue.nsops = nsops;
 	queue.undo = un;
 	queue.pid = task_tgid_vnr(current);
-	queue.id = semid;
 	queue.alter = alter;
 	if (alter)
-		append_to_queue(sma ,&queue);
+		list_add_tail(&queue.list, &sma->sem_pending);
 	else
-		prepend_to_queue(sma ,&queue);
+		list_add(&queue.list, &sma->sem_pending);
 
 	queue.status = -EINTR;
 	queue.sleeper = current;
@@ -1174,7 +1198,6 @@ retry_undos:
 
 	sma = sem_lock(ns, semid);
 	if (IS_ERR(sma)) {
-		BUG_ON(queue.prev != NULL);
 		error = -EIDRM;
 		goto out_free;
 	}
@@ -1192,7 +1215,7 @@ retry_undos:
 	 */
 	if (timeout && jiffies_left == 0)
 		error = -EAGAIN;
-	remove_from_queue(sma,&queue);
+	list_del(&queue.list);
 	goto out_unlock_free;
 
 out_unlock_free:
@@ -1243,56 +1266,62 @@ int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
  */
 void exit_sem(struct task_struct *tsk)
 {
-	struct sem_undo_list *undo_list;
-	struct sem_undo *u, **up;
-	struct ipc_namespace *ns;
+	struct sem_undo_list *ulp;
 
-	undo_list = tsk->sysvsem.undo_list;
-	if (!undo_list)
+	ulp = tsk->sysvsem.undo_list;
+	if (!ulp)
 		return;
 	tsk->sysvsem.undo_list = NULL;
 
-	if (!atomic_dec_and_test(&undo_list->refcnt))
+	if (!atomic_dec_and_test(&ulp->refcnt))
 		return;
 
-	ns = tsk->nsproxy->ipc_ns;
-	/* 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)) {
+	for (;;) {
 		struct sem_array *sma;
-		int nsems, i;
-		struct sem_undo *un, **unp;
+		struct sem_undo *un;
 		int semid;
-	       
-		semid = u->semid;
+		int i;
 
-		if(semid == -1)
-			continue;
-		sma = sem_lock(ns, semid);
+		rcu_read_lock();
+		un = list_entry(rcu_dereference(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;
 
-		if (u->semid == -1)
-			goto next_entry;
+		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;
+		}
 
-		BUG_ON(sem_checkid(sma, u->semid));
+		/* remove un from the linked lists */
+		assert_spin_locked(&sma->sem_perm.lock);
+		list_del(&un->list_id);
 
-		/* 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++) {
+		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 (u->semadj[i]) {
-				semaphore->semval += u->semadj[i];
+			if (un->semadj[i]) {
+				semaphore->semval += un->semadj[i];
 				/*
 				 * Range checks of the new semaphore value,
 				 * not defined by sus:
@@ -1316,10 +1345,11 @@ found:
 		sma->sem_otime = get_seconds();
 		/* maybe some queued-up processes were waiting for this */
 		update_queue(sma);
-next_entry:
 		sem_unlock(sma);
+
+		call_rcu(&un->rcu, free_un);
 	}
-	kfree(undo_list);
+	kfree(ulp);
 }
 
 #ifdef CONFIG_PROC_FS
diff --git a/ipc/shm.c b/ipc/shm.c
index 790240cd067..e77ec698cf4 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -112,23 +112,8 @@ void __init shm_init (void)
 }
 
 /*
- * shm_lock_(check_)down routines are called in the paths where the rw_mutex
- * is held to protect access to the idr tree.
- */
-static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns,
-						int id)
-{
-	struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id);
-
-	if (IS_ERR(ipcp))
-		return (struct shmid_kernel *)ipcp;
-
-	return container_of(ipcp, struct shmid_kernel, shm_perm);
-}
-
-/*
  * shm_lock_(check_) routines are called in the paths where the rw_mutex
- * is not held.
+ * is not necessarily held.
  */
 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
@@ -211,7 +196,7 @@ static void shm_close(struct vm_area_struct *vma)
 
 	down_write(&shm_ids(ns).rw_mutex);
 	/* remove from the list of attaches of the shm segment */
-	shp = shm_lock_down(ns, sfd->id);
+	shp = shm_lock(ns, sfd->id);
 	BUG_ON(IS_ERR(shp));
 	shp->shm_lprid = task_tgid_vnr(current);
 	shp->shm_dtim = get_seconds();
@@ -577,7 +562,8 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 
 		if (is_file_hugepages(shp->shm_file)) {
 			struct address_space *mapping = inode->i_mapping;
-			*rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
+			struct hstate *h = hstate_file(shp->shm_file);
+			*rss += pages_per_huge_page(h) * mapping->nrpages;
 		} else {
 			struct shmem_inode_info *info = SHMEM_I(inode);
 			spin_lock(&info->lock);
@@ -931,7 +917,7 @@ invalid:
 
 out_nattch:
 	down_write(&shm_ids(ns).rw_mutex);
-	shp = shm_lock_down(ns, shmid);
+	shp = shm_lock(ns, shmid);
 	BUG_ON(IS_ERR(shp));
 	shp->shm_nattch--;
 	if(shp->shm_nattch == 0 &&
diff --git a/ipc/util.c b/ipc/util.c
index 3339177b336..49b3ea615dc 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -688,10 +688,6 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
  * Look for an id in the ipc ids idr and lock the associated ipc object.
  *
  * The ipc object is locked on exit.
- *
- * This is the routine that should be called when the rw_mutex is not already
- * held, i.e. idr tree not protected: it protects the idr tree in read mode
- * during the idr_find().
  */
 
 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
@@ -699,18 +695,13 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 	struct kern_ipc_perm *out;
 	int lid = ipcid_to_idx(id);
 
-	down_read(&ids->rw_mutex);
-
 	rcu_read_lock();
 	out = idr_find(&ids->ipcs_idr, lid);
 	if (out == NULL) {
 		rcu_read_unlock();
-		up_read(&ids->rw_mutex);
 		return ERR_PTR(-EINVAL);
 	}
 
-	up_read(&ids->rw_mutex);
-
 	spin_lock(&out->lock);
 	
 	/* ipc_rmid() may have already freed the ID while ipc_lock
@@ -725,56 +716,6 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 	return out;
 }
 
-/**
- * ipc_lock_down - Lock an ipc structure with rw_sem held
- * @ids: IPC identifier set
- * @id: ipc id to look for
- *
- * Look for an id in the ipc ids idr and lock the associated ipc object.
- *
- * The ipc object is locked on exit.
- *
- * This is the routine that should be called when the rw_mutex is already
- * held, i.e. idr tree protected.
- */
-
-struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id)
-{
-	struct kern_ipc_perm *out;
-	int lid = ipcid_to_idx(id);
-
-	rcu_read_lock();
-	out = idr_find(&ids->ipcs_idr, lid);
-	if (out == NULL) {
-		rcu_read_unlock();
-		return ERR_PTR(-EINVAL);
-	}
-
-	spin_lock(&out->lock);
-
-	/*
-	 * No need to verify that the structure is still valid since the
-	 * rw_mutex is held.
-	 */
-	return out;
-}
-
-struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id)
-{
-	struct kern_ipc_perm *out;
-
-	out = ipc_lock_down(ids, id);
-	if (IS_ERR(out))
-		return out;
-
-	if (ipc_checkid(out, id)) {
-		ipc_unlock(out);
-		return ERR_PTR(-EIDRM);
-	}
-
-	return out;
-}
-
 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
 {
 	struct kern_ipc_perm *out;
@@ -846,7 +787,7 @@ struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
 	int err;
 
 	down_write(&ids->rw_mutex);
-	ipcp = ipc_lock_check_down(ids, id);
+	ipcp = ipc_lock_check(ids, id);
 	if (IS_ERR(ipcp)) {
 		err = PTR_ERR(ipcp);
 		goto out_up;
diff --git a/ipc/util.h b/ipc/util.h
index cdb966aebe0..3646b45a03c 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -102,11 +102,6 @@ void* ipc_rcu_alloc(int size);
 void ipc_rcu_getref(void *ptr);
 void ipc_rcu_putref(void *ptr);
 
-/*
- * ipc_lock_down: called with rw_mutex held
- * ipc_lock: called without that lock held
- */
-struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 
 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
@@ -155,7 +150,6 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)
 	rcu_read_unlock();
 }
 
-struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id);
 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 			struct ipc_ops *ops, struct ipc_params *params);