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Date: Wed, 15 May 2013 18:08:05 -0700
From: Davidlohr Bueso <davidlohr.bueso@...com>
To: akpm@...ux-foundation.org
Cc: torvalds@...ux-foundation.org, riel@...hat.com,
linux-kernel@...r.kernel.org,
Davidlohr Bueso <davidlohr.bueso@...com>
Subject: [PATCH 06/11] 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: Davidlohr Bueso <davidlohr.bueso@...com>
---
ipc/msg.c | 49 ++++++++++++++++++++++++++++++++++---------------
1 file changed, 34 insertions(+), 15 deletions(-)
diff --git a/ipc/msg.c b/ipc/msg.c
index 264ebe0..20361b5 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -469,17 +469,11 @@ out_up:
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:
@@ -490,6 +484,7 @@ 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
@@ -521,7 +516,8 @@ 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;
@@ -565,19 +561,42 @@ 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 -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)
--
1.7.11.7
--
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