diff options
Diffstat (limited to 'ipc/msg.c')
| -rw-r--r-- | ipc/msg.c | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index b7274dbf091..413bf9c7aec 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -34,7 +34,7 @@ #include <linux/syscalls.h> #include <linux/audit.h> #include <linux/seq_file.h> -#include <linux/mutex.h> +#include <linux/rwsem.h> #include <linux/nsproxy.h> #include <asm/current.h> @@ -110,7 +110,7 @@ void msg_exit_ns(struct ipc_namespace *ns) int next_id; int total, in_use; - mutex_lock(&msg_ids(ns).mutex); + down_write(&msg_ids(ns).rw_mutex); in_use = msg_ids(ns).in_use; @@ -122,7 +122,8 @@ void msg_exit_ns(struct ipc_namespace *ns) freeque(ns, msq); total++; } - mutex_unlock(&msg_ids(ns).mutex); + + up_write(&msg_ids(ns).rw_mutex); kfree(ns->ids[IPC_MSG_IDS]); ns->ids[IPC_MSG_IDS] = NULL; @@ -136,6 +137,22 @@ void __init msg_init(void) IPC_MSG_IDS, sysvipc_msg_proc_show); } +/* + * This routine is called in the paths where the rw_mutex is held to protect + * access to the idr tree. + */ +static inline struct msg_queue *msg_lock_check_down(struct ipc_namespace *ns, + int id) +{ + struct kern_ipc_perm *ipcp = ipc_lock_check_down(&msg_ids(ns), id); + + return container_of(ipcp, struct msg_queue, q_perm); +} + +/* + * msg_lock_(check_) routines are called in the paths where the rw_mutex + * is not held. + */ static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id) { struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id); @@ -161,7 +178,7 @@ static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) * @ns: namespace * @params: ptr to the structure that contains the key and msgflg * - * Called with msg_ids.mutex held + * Called with msg_ids.rw_mutex held (writer) */ static int newque(struct ipc_namespace *ns, struct ipc_params *params) { @@ -260,8 +277,8 @@ static void expunge_all(struct msg_queue *msq, int res) * removes the message queue from message queue ID IDR, and cleans up all the * messages associated with this queue. * - * msg_ids.mutex and the spinlock for this message queue are held - * before freeque() is called. msg_ids.mutex remains locked on exit. + * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held + * before freeque() is called. msg_ids.rw_mutex remains locked on exit. */ static void freeque(struct ipc_namespace *ns, struct msg_queue *msq) { @@ -286,7 +303,7 @@ static void freeque(struct ipc_namespace *ns, struct msg_queue *msq) } /* - * Called with msg_ids.mutex and ipcp locked. + * Called with msg_ids.rw_mutex and ipcp locked. */ static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg) { @@ -444,7 +461,7 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) msginfo.msgmnb = ns->msg_ctlmnb; msginfo.msgssz = MSGSSZ; msginfo.msgseg = MSGSEG; - mutex_lock(&msg_ids(ns).mutex); + down_read(&msg_ids(ns).rw_mutex); if (cmd == MSG_INFO) { msginfo.msgpool = msg_ids(ns).in_use; msginfo.msgmap = atomic_read(&msg_hdrs); @@ -455,7 +472,7 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) msginfo.msgtql = MSGTQL; } max_id = ipc_get_maxid(&msg_ids(ns)); - mutex_unlock(&msg_ids(ns).mutex); + up_read(&msg_ids(ns).rw_mutex); if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) return -EFAULT; return (max_id < 0) ? 0 : max_id; @@ -516,8 +533,8 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) return -EINVAL; } - mutex_lock(&msg_ids(ns).mutex); - msq = msg_lock_check(ns, msqid); + down_write(&msg_ids(ns).rw_mutex); + msq = msg_lock_check_down(ns, msqid); if (IS_ERR(msq)) { err = PTR_ERR(msq); goto out_up; @@ -576,7 +593,7 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) } err = 0; out_up: - mutex_unlock(&msg_ids(ns).mutex); + up_write(&msg_ids(ns).rw_mutex); return err; out_unlock_up: msg_unlock(msq); |