1 files changed, 130 insertions, 43 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 609d53f..3c72a05 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -50,6 +50,12 @@
 #define STATE_PENDING	1
 #define STATE_READY	2
 
+struct posix_msg_tree_node {
+	struct rb_node		rb_node;
+	struct list_head	msg_list;
+	int			priority;
+};
+
 struct ext_wait_queue {		/* queue of sleeping tasks */
 	struct task_struct *task;
 	struct list_head list;
@@ -62,7 +68,7 @@ struct mqueue_inode_info {
 	struct inode vfs_inode;
 	wait_queue_head_t wait_q;
 
-	struct msg_msg **messages;
+	struct rb_root msg_tree;
 	struct mq_attr attr;
 
 	struct sigevent notify;
@@ -110,6 +116,90 @@ static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
 	return ns;
 }
 
+/* Auxiliary functions to manipulate messages' list */
+static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
+{
+	struct rb_node **p, *parent = NULL;
+	struct posix_msg_tree_node *leaf;
+
+	p = &info->msg_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
+
+		if (likely(leaf->priority == msg->m_type))
+			goto insert_msg;
+		else if (msg->m_type < leaf->priority)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+	leaf = kzalloc(sizeof(*leaf), GFP_ATOMIC);
+	if (!leaf)
+		return -ENOMEM;
+	rb_init_node(&leaf->rb_node);
+	INIT_LIST_HEAD(&leaf->msg_list);
+	leaf->priority = msg->m_type;
+	rb_link_node(&leaf->rb_node, parent, p);
+	rb_insert_color(&leaf->rb_node, &info->msg_tree);
+	info->qsize += sizeof(struct posix_msg_tree_node);
+insert_msg:
+	info->attr.mq_curmsgs++;
+	info->qsize += msg->m_ts;
+	list_add_tail(&msg->m_list, &leaf->msg_list);
+	return 0;
+}
+
+static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
+{
+	struct rb_node **p, *parent = NULL;
+	struct posix_msg_tree_node *leaf;
+	struct msg_msg *msg;
+
+try_again:
+	p = &info->msg_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		/*
+		 * During insert, low priorities go to the left and high to the
+		 * right.  On receive, we want the highest priorities first, so
+		 * walk all the way to the right.
+		 */
+		p = &(*p)->rb_right;
+	}
+	if (!parent) {
+		if (info->attr.mq_curmsgs) {
+			pr_warn_once("Inconsistency in POSIX message queue, "
+				     "no tree element, but supposedly messages "
+				     "should exist!\n");
+			info->attr.mq_curmsgs = 0;
+		}
+		return NULL;
+	}
+	leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
+	if (list_empty(&leaf->msg_list)) {
+		pr_warn_once("Inconsistency in POSIX message queue, "
+			     "empty leaf node but we haven't implemented "
+			     "lazy leaf delete!\n");
+		rb_erase(&leaf->rb_node, &info->msg_tree);
+		info->qsize -= sizeof(struct posix_msg_tree_node);
+		kfree(leaf);
+		goto try_again;
+	} else {
+		msg = list_first_entry(&leaf->msg_list,
+				       struct msg_msg, m_list);
+		list_del(&msg->m_list);
+		if (list_empty(&leaf->msg_list)) {
+			rb_erase(&leaf->rb_node, &info->msg_tree);
+			info->qsize -= sizeof(struct posix_msg_tree_node);
+			kfree(leaf);
+		}
+	}
+	info->attr.mq_curmsgs--;
+	info->qsize -= msg->m_ts;
+	return msg;
+}
+
 static struct inode *mqueue_get_inode(struct super_block *sb,
 		struct ipc_namespace *ipc_ns, umode_t mode,
 		struct mq_attr *attr)
@@ -130,7 +220,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 
 	if (S_ISREG(mode)) {
 		struct mqueue_inode_info *info;
-		unsigned long mq_bytes, mq_msg_tblsz;
+		unsigned long mq_bytes, mq_treesize;
 
 		inode->i_fop = &mqueue_file_operations;
 		inode->i_size = FILENT_SIZE;
@@ -144,6 +234,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 		info->notify_user_ns = NULL;
 		info->qsize = 0;
 		info->user = NULL;	/* set when all is ok */
+		info->msg_tree = RB_ROOT;
 		memset(&info->attr, 0, sizeof(info->attr));
 		info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
 					   ipc_ns->mq_msg_default);
@@ -153,16 +244,25 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 			info->attr.mq_maxmsg = attr->mq_maxmsg;
 			info->attr.mq_msgsize = attr->mq_msgsize;
 		}
-		mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
-		if (mq_msg_tblsz > PAGE_SIZE)
-			info->messages = vmalloc(mq_msg_tblsz);
-		else
-			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
-		if (!info->messages)
-			goto out_inode;
+		/*
+		 * We used to allocate a static array of pointers and account
+		 * the size of that array as well as one msg_msg struct per
+		 * possible message into the queue size. That's no longer
+		 * accurate as the queue is now an rbtree and will grow and
+		 * shrink depending on usage patterns.  We can, however, still
+		 * account one msg_msg struct per message, but the nodes are
+		 * allocated depending on priority usage, and most programs
+		 * only use one, or a handful, of priorities.  However, since
+		 * this is pinned memory, we need to assume worst case, so
+		 * that means the min(mq_maxmsg, max_priorities) * struct
+		 * posix_msg_tree_node.
+		 */
+		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
+			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
+			sizeof(struct posix_msg_tree_node);
 
-		mq_bytes = (mq_msg_tblsz +
-			(info->attr.mq_maxmsg * info->attr.mq_msgsize));
+		mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
+					  info->attr.mq_msgsize);
 
 		spin_lock(&mq_lock);
 		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
@@ -253,9 +353,9 @@ static void mqueue_evict_inode(struct inode *inode)
 {
 	struct mqueue_inode_info *info;
 	struct user_struct *user;
-	unsigned long mq_bytes;
-	int i;
+	unsigned long mq_bytes, mq_treesize;
 	struct ipc_namespace *ipc_ns;
+	struct msg_msg *msg;
 
 	clear_inode(inode);
 
@@ -265,17 +365,18 @@ static void mqueue_evict_inode(struct inode *inode)
 	ipc_ns = get_ns_from_inode(inode);
 	info = MQUEUE_I(inode);
 	spin_lock(&info->lock);
-	for (i = 0; i < info->attr.mq_curmsgs; i++)
-		free_msg(info->messages[i]);
-	if (is_vmalloc_addr(info->messages))
-		vfree(info->messages);
-	else
-		kfree(info->messages);
+	while ((msg = msg_get(info)) != NULL)
+		free_msg(msg);
 	spin_unlock(&info->lock);
 
 	/* Total amount of bytes accounted for the mqueue */
-	mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
-	    + info->attr.mq_msgsize);
+	mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
+		min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
+		sizeof(struct posix_msg_tree_node);
+
+	mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
+				  info->attr.mq_msgsize);
+
 	user = info->user;
 	if (user) {
 		spin_lock(&mq_lock);
@@ -495,26 +596,6 @@ static struct ext_wait_queue *wq_get_first_waiter(
 	return list_entry(ptr, struct ext_wait_queue, list);
 }
 
-/* Auxiliary functions to manipulate messages' list */
-static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
-{
-	int k;
-
-	k = info->attr.mq_curmsgs - 1;
-	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
-		info->messages[k + 1] = info->messages[k];
-		k--;
-	}
-	info->attr.mq_curmsgs++;
-	info->qsize += ptr->m_ts;
-	info->messages[k + 1] = ptr;
-}
-
-static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
-{
-	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
-	return info->messages[info->attr.mq_curmsgs];
-}
 
 static inline void set_cookie(struct sk_buff *skb, char code)
 {
@@ -848,7 +929,8 @@ static inline void pipelined_receive(struct mqueue_inode_info *info)
 		wake_up_interruptible(&info->wait_q);
 		return;
 	}
-	msg_insert(sender->msg, info);
+	if (msg_insert(sender->msg, info))
+		return;
 	list_del(&sender->list);
 	sender->state = STATE_PENDING;
 	wake_up_process(sender->task);
@@ -936,7 +1018,12 @@ SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 			pipelined_send(info, msg_ptr, receiver);
 		} else {
 			/* adds message to the queue */
-			msg_insert(msg_ptr, info);
+			if (msg_insert(msg_ptr, info)) {
+				free_msg(msg_ptr);
+				ret = -ENOMEM;
+				spin_unlock(&info->lock);
+				goto out_fput;
+			}
 			__do_notify(info);
 		}
 		inode->i_atime = inode->i_mtime = inode->i_ctime =