[PATCH 1/2] IPC: mqueue, refactor failure handling

[PATCH 1/2] IPC: mqueue, refactor failure handling

[Jiri Slaby]

If new_inode fails to allocate an inode we need only to return with
NULL. But now we test the opposite and have all the work in a nested
block. So do the opposite to save one indentation level (and remove
unnecessary line breaks).

This is only a preparation/cleanup for the next patch where we fix up
return values from mqueue_get_inode.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
I don't know who to send this to. Neither MAINTAINERS nor git log
shows somebody taking care about the code. Maybe you have a better
code=>people mapping file, Andrew?

 ipc/mqueue.c |  115 +++++++++++++++++++++++++++++-----------------------------
 1 files changed, 58 insertions(+), 57 deletions(-)

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 14fb6d6..d43c30f 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -115,69 +115,70 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 	struct inode *inode;
 
 	inode = new_inode(sb);
-	if (inode) {
-		inode->i_ino = get_next_ino();
-		inode->i_mode = mode;
-		inode->i_uid = current_fsuid();
-		inode->i_gid = current_fsgid();
-		inode->i_mtime = inode->i_ctime = inode->i_atime =
-				CURRENT_TIME;
+	if (!inode)
+		goto err;
 
-		if (S_ISREG(mode)) {
-			struct mqueue_inode_info *info;
-			struct task_struct *p = current;
-			unsigned long mq_bytes, mq_msg_tblsz;
-
-			inode->i_fop = &mqueue_file_operations;
-			inode->i_size = FILENT_SIZE;
-			/* mqueue specific info */
-			info = MQUEUE_I(inode);
-			spin_lock_init(&info->lock);
-			init_waitqueue_head(&info->wait_q);
-			INIT_LIST_HEAD(&info->e_wait_q[0].list);
-			INIT_LIST_HEAD(&info->e_wait_q[1].list);
-			info->notify_owner = NULL;
-			info->qsize = 0;
-			info->user = NULL;	/* set when all is ok */
-			memset(&info->attr, 0, sizeof(info->attr));
-			info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
-			info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
-			if (attr) {
-				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 *);
-			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
-			if (!info->messages)
-				goto out_inode;
-
-			mq_bytes = (mq_msg_tblsz +
-				(info->attr.mq_maxmsg * info->attr.mq_msgsize));
-
-			spin_lock(&mq_lock);
-			if (u->mq_bytes + mq_bytes < u->mq_bytes ||
-		 	    u->mq_bytes + mq_bytes >
-			    task_rlimit(p, RLIMIT_MSGQUEUE)) {
-				spin_unlock(&mq_lock);
-				/* mqueue_evict_inode() releases info->messages */
-				goto out_inode;
-			}
-			u->mq_bytes += mq_bytes;
-			spin_unlock(&mq_lock);
+	inode->i_ino = get_next_ino();
+	inode->i_mode = mode;
+	inode->i_uid = current_fsuid();
+	inode->i_gid = current_fsgid();
+	inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
+
+	if (S_ISREG(mode)) {
+		struct mqueue_inode_info *info;
+		struct task_struct *p = current;
+		unsigned long mq_bytes, mq_msg_tblsz;
+
+		inode->i_fop = &mqueue_file_operations;
+		inode->i_size = FILENT_SIZE;
+		/* mqueue specific info */
+		info = MQUEUE_I(inode);
+		spin_lock_init(&info->lock);
+		init_waitqueue_head(&info->wait_q);
+		INIT_LIST_HEAD(&info->e_wait_q[0].list);
+		INIT_LIST_HEAD(&info->e_wait_q[1].list);
+		info->notify_owner = NULL;
+		info->qsize = 0;
+		info->user = NULL;	/* set when all is ok */
+		memset(&info->attr, 0, sizeof(info->attr));
+		info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
+		info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
+		if (attr) {
+			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 *);
+		info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
+		if (!info->messages)
+			goto out_inode;
 
-			/* all is ok */
-			info->user = get_uid(u);
-		} else if (S_ISDIR(mode)) {
-			inc_nlink(inode);
-			/* Some things misbehave if size == 0 on a directory */
-			inode->i_size = 2 * DIRENT_SIZE;
-			inode->i_op = &mqueue_dir_inode_operations;
-			inode->i_fop = &simple_dir_operations;
+		mq_bytes = (mq_msg_tblsz +
+			(info->attr.mq_maxmsg * info->attr.mq_msgsize));
+
+		spin_lock(&mq_lock);
+		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
+		    u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
+			spin_unlock(&mq_lock);
+			/* mqueue_evict_inode() releases info->messages */
+			goto out_inode;
 		}
+		u->mq_bytes += mq_bytes;
+		spin_unlock(&mq_lock);
+
+		/* all is ok */
+		info->user = get_uid(u);
+	} else if (S_ISDIR(mode)) {
+		inc_nlink(inode);
+		/* Some things misbehave if size == 0 on a directory */
+		inode->i_size = 2 * DIRENT_SIZE;
+		inode->i_op = &mqueue_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
 	}
+
 	return inode;
 out_inode:
 	iput(inode);
+err:
 	return NULL;
 }
 
-- 
1.7.4.2

[PATCH 2/2] IPC: mqueue, fix mq_open return value

[Jiri Slaby]

We return ENOMEM from mqueue_get_inode even when we have enough
memory. Namely in case the system rlimit of mqueue was reached. This
error propagates to mq_queue and user sees the error unexpectedly. So
fix this up to properly return EMFILE as described in the manpage:
	EMFILE The process already has the maximum number of files and
	       message queues open.
instead of:
	ENOMEM Insufficient memory.

With the previous patch we just switch to ERR_PTR/PTR_ERR/IS_ERR
error handling here.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 ipc/mqueue.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index d43c30f..ed049ea 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -113,6 +113,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 {
 	struct user_struct *u = current_user();
 	struct inode *inode;
+	int ret = -ENOMEM;
 
 	inode = new_inode(sb);
 	if (!inode)
@@ -160,6 +161,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 		    u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
 			spin_unlock(&mq_lock);
 			/* mqueue_evict_inode() releases info->messages */
+			ret = -EMFILE;
 			goto out_inode;
 		}
 		u->mq_bytes += mq_bytes;
@@ -179,7 +181,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 out_inode:
 	iput(inode);
 err:
-	return NULL;
+	return ERR_PTR(ret);
 }
 
 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
@@ -195,8 +197,8 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
 
 	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
 				NULL);
-	if (!inode) {
-		error = -ENOMEM;
+	if (IS_ERR(inode)) {
+		error = PTR_ERR(inode);
 		goto out;
 	}
 
@@ -316,8 +318,8 @@ static int mqueue_create(struct inode *dir, struct dentry *dentry,
 	spin_unlock(&mq_lock);
 
 	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
-	if (!inode) {
-		error = -ENOMEM;
+	if (IS_ERR(inode)) {
+		error = PTR_ERR(inode);
 		spin_lock(&mq_lock);
 		ipc_ns->mq_queues_count--;
 		goto out_unlock;
-- 
1.7.4.2