From 2cafed30f150f7314f98717b372df8173516cae0 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Mon, 8 Jul 2013 16:01:14 -0700 Subject: [PATCH] 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 Cc: Andi Kleen Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/msg.c | 49 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 34 insertions(+), 15 deletions(-) diff --git a/ipc/msg.c b/ipc/msg.c index de422ff71c87..f45be81f6de9 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -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 -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) -- GitLab