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Commit 2cafed30 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
Browse files

ipc,msg: introduce msgctl_nolock 



Similar to semctl, when calling msgctl, the *_INFO and *_STAT commands
can be performed without acquiring the ipc object.

Add a msgctl_nolock() function and move the logic of *_INFO and *_STAT
out of msgctl().  This change still takes the lock and it will be
properly lockless in the next patch

Signed-off-by: default avatarDavidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 15724ecb

ipc/msg.c

+34 −15
Original line number Diff line number Diff line
@@ -467,17 +467,11 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, 
	return err;

}



SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)

static int msgctl_nolock(struct ipc_namespace *ns, int msqid,

			 int cmd, int version, void __user *buf)

{

	int err;

	struct msg_queue *msq;

	int err, version;

	struct ipc_namespace *ns;



	if (msqid < 0 || cmd < 0)

		return -EINVAL;



	version = ipc_parse_version(&cmd);

	ns = current->nsproxy->ipc_ns;



	switch (cmd) {

	case IPC_INFO:
@@ -488,6 +482,7 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 


		if (!buf)

			return -EFAULT;



		/*

		 * We must not return kernel stack data.

		 * due to padding, it's not enough
@@ -519,7 +514,8 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 
			return -EFAULT;

		return (max_id < 0) ? 0 : max_id;

	}

	case MSG_STAT:	/* msqid is an index rather than a msg queue id */



	case MSG_STAT:

	case IPC_STAT:

	{

		struct msqid64_ds tbuf;
@@ -563,19 +559,42 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) 
			return -EFAULT;

		return success_return;

	}

	case IPC_SET:

	case IPC_RMID:

		err = msgctl_down(ns, msqid, cmd, buf, version);

		return err;



	default:

		return -EINVAL;

	}



	return err;

out_unlock:

	msg_unlock(msq);

	return err;

}



SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)

{

	int version;

	struct ipc_namespace *ns;



	if (msqid < 0 || cmd < 0)

		return -EINVAL;



	version = ipc_parse_version(&cmd);

	ns = current->nsproxy->ipc_ns;



	switch (cmd) {

	case IPC_INFO:

	case MSG_INFO:

	case MSG_STAT:	/* msqid is an index rather than a msg queue id */

	case IPC_STAT:

		return msgctl_nolock(ns, msqid, cmd, version, buf);

	case IPC_SET:

	case IPC_RMID:

		return msgctl_down(ns, msqid, cmd, buf, version);

	default:

		return  -EINVAL;

	}

}



static int testmsg(struct msg_msg *msg, long type, int mode)

{

	switch(mode)