3 * Copyright (C) 1992 Krishna Balasubramanian
5 * Removed all the remaining kerneld mess
6 * Catch the -EFAULT stuff properly
7 * Use GFP_KERNEL for messages as in 1.2
8 * Fixed up the unchecked user space derefs
9 * Copyright (C) 1998 Alan Cox & Andi Kleen
11 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
13 * mostly rewritten, threaded and wake-one semantics added
14 * MSGMAX limit removed, sysctl's added
15 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
17 * support for audit of ipc object properties and permission changes
18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
22 * Pavel Emelianov <xemul@openvz.org>
25 #include <linux/capability.h>
26 #include <linux/msg.h>
27 #include <linux/spinlock.h>
28 #include <linux/init.h>
30 #include <linux/proc_fs.h>
31 #include <linux/list.h>
32 #include <linux/security.h>
33 #include <linux/sched.h>
34 #include <linux/syscalls.h>
35 #include <linux/audit.h>
36 #include <linux/seq_file.h>
37 #include <linux/rwsem.h>
38 #include <linux/nsproxy.h>
39 #include <linux/ipc_namespace.h>
41 #include <asm/current.h>
42 #include <linux/uaccess.h>
45 /* one msg_receiver structure for each sleeping receiver */
47 struct list_head r_list
;
48 struct task_struct
*r_tsk
;
55 * Mark r_msg volatile so that the compiler
56 * does not try to get smart and optimize
57 * it. We rely on this for the lockless
60 struct msg_msg
*volatile r_msg
;
63 /* one msg_sender for each sleeping sender */
65 struct list_head list
;
66 struct task_struct
*tsk
;
70 #define SEARCH_EQUAL 2
71 #define SEARCH_NOTEQUAL 3
72 #define SEARCH_LESSEQUAL 4
73 #define SEARCH_NUMBER 5
75 #define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
77 static inline struct msg_queue
*msq_obtain_object(struct ipc_namespace
*ns
, int id
)
79 struct kern_ipc_perm
*ipcp
= ipc_obtain_object(&msg_ids(ns
), id
);
82 return ERR_CAST(ipcp
);
84 return container_of(ipcp
, struct msg_queue
, q_perm
);
87 static inline struct msg_queue
*msq_obtain_object_check(struct ipc_namespace
*ns
,
90 struct kern_ipc_perm
*ipcp
= ipc_obtain_object_check(&msg_ids(ns
), id
);
93 return ERR_CAST(ipcp
);
95 return container_of(ipcp
, struct msg_queue
, q_perm
);
98 static inline void msg_rmid(struct ipc_namespace
*ns
, struct msg_queue
*s
)
100 ipc_rmid(&msg_ids(ns
), &s
->q_perm
);
103 static void msg_rcu_free(struct rcu_head
*head
)
105 struct ipc_rcu
*p
= container_of(head
, struct ipc_rcu
, rcu
);
106 struct msg_queue
*msq
= ipc_rcu_to_struct(p
);
108 security_msg_queue_free(msq
);
113 * newque - Create a new msg queue
115 * @params: ptr to the structure that contains the key and msgflg
117 * Called with msg_ids.rwsem held (writer)
119 static int newque(struct ipc_namespace
*ns
, struct ipc_params
*params
)
121 struct msg_queue
*msq
;
123 key_t key
= params
->key
;
124 int msgflg
= params
->flg
;
126 msq
= ipc_rcu_alloc(sizeof(*msq
));
130 msq
->q_perm
.mode
= msgflg
& S_IRWXUGO
;
131 msq
->q_perm
.key
= key
;
133 msq
->q_perm
.security
= NULL
;
134 retval
= security_msg_queue_alloc(msq
);
136 ipc_rcu_putref(msq
, ipc_rcu_free
);
140 /* ipc_addid() locks msq upon success. */
141 id
= ipc_addid(&msg_ids(ns
), &msq
->q_perm
, ns
->msg_ctlmni
);
143 ipc_rcu_putref(msq
, msg_rcu_free
);
147 msq
->q_stime
= msq
->q_rtime
= 0;
148 msq
->q_ctime
= get_seconds();
149 msq
->q_cbytes
= msq
->q_qnum
= 0;
150 msq
->q_qbytes
= ns
->msg_ctlmnb
;
151 msq
->q_lspid
= msq
->q_lrpid
= 0;
152 INIT_LIST_HEAD(&msq
->q_messages
);
153 INIT_LIST_HEAD(&msq
->q_receivers
);
154 INIT_LIST_HEAD(&msq
->q_senders
);
156 ipc_unlock_object(&msq
->q_perm
);
159 return msq
->q_perm
.id
;
162 static inline void ss_add(struct msg_queue
*msq
, struct msg_sender
*mss
)
165 __set_current_state(TASK_INTERRUPTIBLE
);
166 list_add_tail(&mss
->list
, &msq
->q_senders
);
169 static inline void ss_del(struct msg_sender
*mss
)
171 if (mss
->list
.next
!= NULL
)
172 list_del(&mss
->list
);
175 static void ss_wakeup(struct list_head
*h
, int kill
)
177 struct msg_sender
*mss
, *t
;
179 list_for_each_entry_safe(mss
, t
, h
, list
) {
181 mss
->list
.next
= NULL
;
182 wake_up_process(mss
->tsk
);
186 static void expunge_all(struct msg_queue
*msq
, int res
)
188 struct msg_receiver
*msr
, *t
;
190 list_for_each_entry_safe(msr
, t
, &msq
->q_receivers
, r_list
) {
191 msr
->r_msg
= NULL
; /* initialize expunge ordering */
192 wake_up_process(msr
->r_tsk
);
194 * Ensure that the wakeup is visible before setting r_msg as
195 * the receiving end depends on it: either spinning on a nil,
196 * or dealing with -EAGAIN cases. See lockless receive part 1
197 * and 2 in do_msgrcv().
200 msr
->r_msg
= ERR_PTR(res
);
205 * freeque() wakes up waiters on the sender and receiver waiting queue,
206 * removes the message queue from message queue ID IDR, and cleans up all the
207 * messages associated with this queue.
209 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
210 * before freeque() is called. msg_ids.rwsem remains locked on exit.
212 static void freeque(struct ipc_namespace
*ns
, struct kern_ipc_perm
*ipcp
)
214 struct msg_msg
*msg
, *t
;
215 struct msg_queue
*msq
= container_of(ipcp
, struct msg_queue
, q_perm
);
217 expunge_all(msq
, -EIDRM
);
218 ss_wakeup(&msq
->q_senders
, 1);
220 ipc_unlock_object(&msq
->q_perm
);
223 list_for_each_entry_safe(msg
, t
, &msq
->q_messages
, m_list
) {
224 atomic_dec(&ns
->msg_hdrs
);
227 atomic_sub(msq
->q_cbytes
, &ns
->msg_bytes
);
228 ipc_rcu_putref(msq
, msg_rcu_free
);
232 * Called with msg_ids.rwsem and ipcp locked.
234 static inline int msg_security(struct kern_ipc_perm
*ipcp
, int msgflg
)
236 struct msg_queue
*msq
= container_of(ipcp
, struct msg_queue
, q_perm
);
238 return security_msg_queue_associate(msq
, msgflg
);
241 SYSCALL_DEFINE2(msgget
, key_t
, key
, int, msgflg
)
243 struct ipc_namespace
*ns
;
244 static const struct ipc_ops msg_ops
= {
246 .associate
= msg_security
,
248 struct ipc_params msg_params
;
250 ns
= current
->nsproxy
->ipc_ns
;
252 msg_params
.key
= key
;
253 msg_params
.flg
= msgflg
;
255 return ipcget(ns
, &msg_ids(ns
), &msg_ops
, &msg_params
);
258 static inline unsigned long
259 copy_msqid_to_user(void __user
*buf
, struct msqid64_ds
*in
, int version
)
263 return copy_to_user(buf
, in
, sizeof(*in
));
268 memset(&out
, 0, sizeof(out
));
270 ipc64_perm_to_ipc_perm(&in
->msg_perm
, &out
.msg_perm
);
272 out
.msg_stime
= in
->msg_stime
;
273 out
.msg_rtime
= in
->msg_rtime
;
274 out
.msg_ctime
= in
->msg_ctime
;
276 if (in
->msg_cbytes
> USHRT_MAX
)
277 out
.msg_cbytes
= USHRT_MAX
;
279 out
.msg_cbytes
= in
->msg_cbytes
;
280 out
.msg_lcbytes
= in
->msg_cbytes
;
282 if (in
->msg_qnum
> USHRT_MAX
)
283 out
.msg_qnum
= USHRT_MAX
;
285 out
.msg_qnum
= in
->msg_qnum
;
287 if (in
->msg_qbytes
> USHRT_MAX
)
288 out
.msg_qbytes
= USHRT_MAX
;
290 out
.msg_qbytes
= in
->msg_qbytes
;
291 out
.msg_lqbytes
= in
->msg_qbytes
;
293 out
.msg_lspid
= in
->msg_lspid
;
294 out
.msg_lrpid
= in
->msg_lrpid
;
296 return copy_to_user(buf
, &out
, sizeof(out
));
303 static inline unsigned long
304 copy_msqid_from_user(struct msqid64_ds
*out
, void __user
*buf
, int version
)
308 if (copy_from_user(out
, buf
, sizeof(*out
)))
313 struct msqid_ds tbuf_old
;
315 if (copy_from_user(&tbuf_old
, buf
, sizeof(tbuf_old
)))
318 out
->msg_perm
.uid
= tbuf_old
.msg_perm
.uid
;
319 out
->msg_perm
.gid
= tbuf_old
.msg_perm
.gid
;
320 out
->msg_perm
.mode
= tbuf_old
.msg_perm
.mode
;
322 if (tbuf_old
.msg_qbytes
== 0)
323 out
->msg_qbytes
= tbuf_old
.msg_lqbytes
;
325 out
->msg_qbytes
= tbuf_old
.msg_qbytes
;
335 * This function handles some msgctl commands which require the rwsem
336 * to be held in write mode.
337 * NOTE: no locks must be held, the rwsem is taken inside this function.
339 static int msgctl_down(struct ipc_namespace
*ns
, int msqid
, int cmd
,
340 struct msqid_ds __user
*buf
, int version
)
342 struct kern_ipc_perm
*ipcp
;
343 struct msqid64_ds
uninitialized_var(msqid64
);
344 struct msg_queue
*msq
;
347 if (cmd
== IPC_SET
) {
348 if (copy_msqid_from_user(&msqid64
, buf
, version
))
352 down_write(&msg_ids(ns
).rwsem
);
355 ipcp
= ipcctl_pre_down_nolock(ns
, &msg_ids(ns
), msqid
, cmd
,
356 &msqid64
.msg_perm
, msqid64
.msg_qbytes
);
362 msq
= container_of(ipcp
, struct msg_queue
, q_perm
);
364 err
= security_msg_queue_msgctl(msq
, cmd
);
370 ipc_lock_object(&msq
->q_perm
);
371 /* freeque unlocks the ipc object and rcu */
375 if (msqid64
.msg_qbytes
> ns
->msg_ctlmnb
&&
376 !capable(CAP_SYS_RESOURCE
)) {
381 ipc_lock_object(&msq
->q_perm
);
382 err
= ipc_update_perm(&msqid64
.msg_perm
, ipcp
);
386 msq
->q_qbytes
= msqid64
.msg_qbytes
;
388 msq
->q_ctime
= get_seconds();
389 /* sleeping receivers might be excluded by
390 * stricter permissions.
392 expunge_all(msq
, -EAGAIN
);
393 /* sleeping senders might be able to send
394 * due to a larger queue size.
396 ss_wakeup(&msq
->q_senders
, 0);
404 ipc_unlock_object(&msq
->q_perm
);
408 up_write(&msg_ids(ns
).rwsem
);
412 static int msgctl_nolock(struct ipc_namespace
*ns
, int msqid
,
413 int cmd
, int version
, void __user
*buf
)
416 struct msg_queue
*msq
;
422 struct msginfo msginfo
;
429 * We must not return kernel stack data.
430 * due to padding, it's not enough
431 * to set all member fields.
433 err
= security_msg_queue_msgctl(NULL
, cmd
);
437 memset(&msginfo
, 0, sizeof(msginfo
));
438 msginfo
.msgmni
= ns
->msg_ctlmni
;
439 msginfo
.msgmax
= ns
->msg_ctlmax
;
440 msginfo
.msgmnb
= ns
->msg_ctlmnb
;
441 msginfo
.msgssz
= MSGSSZ
;
442 msginfo
.msgseg
= MSGSEG
;
443 down_read(&msg_ids(ns
).rwsem
);
444 if (cmd
== MSG_INFO
) {
445 msginfo
.msgpool
= msg_ids(ns
).in_use
;
446 msginfo
.msgmap
= atomic_read(&ns
->msg_hdrs
);
447 msginfo
.msgtql
= atomic_read(&ns
->msg_bytes
);
449 msginfo
.msgmap
= MSGMAP
;
450 msginfo
.msgpool
= MSGPOOL
;
451 msginfo
.msgtql
= MSGTQL
;
453 max_id
= ipc_get_maxid(&msg_ids(ns
));
454 up_read(&msg_ids(ns
).rwsem
);
455 if (copy_to_user(buf
, &msginfo
, sizeof(struct msginfo
)))
457 return (max_id
< 0) ? 0 : max_id
;
463 struct msqid64_ds tbuf
;
469 memset(&tbuf
, 0, sizeof(tbuf
));
472 if (cmd
== MSG_STAT
) {
473 msq
= msq_obtain_object(ns
, msqid
);
478 success_return
= msq
->q_perm
.id
;
480 msq
= msq_obtain_object_check(ns
, msqid
);
489 if (ipcperms(ns
, &msq
->q_perm
, S_IRUGO
))
492 err
= security_msg_queue_msgctl(msq
, cmd
);
496 kernel_to_ipc64_perm(&msq
->q_perm
, &tbuf
.msg_perm
);
497 tbuf
.msg_stime
= msq
->q_stime
;
498 tbuf
.msg_rtime
= msq
->q_rtime
;
499 tbuf
.msg_ctime
= msq
->q_ctime
;
500 tbuf
.msg_cbytes
= msq
->q_cbytes
;
501 tbuf
.msg_qnum
= msq
->q_qnum
;
502 tbuf
.msg_qbytes
= msq
->q_qbytes
;
503 tbuf
.msg_lspid
= msq
->q_lspid
;
504 tbuf
.msg_lrpid
= msq
->q_lrpid
;
507 if (copy_msqid_to_user(buf
, &tbuf
, version
))
509 return success_return
;
522 SYSCALL_DEFINE3(msgctl
, int, msqid
, int, cmd
, struct msqid_ds __user
*, buf
)
525 struct ipc_namespace
*ns
;
527 if (msqid
< 0 || cmd
< 0)
530 version
= ipc_parse_version(&cmd
);
531 ns
= current
->nsproxy
->ipc_ns
;
536 case MSG_STAT
: /* msqid is an index rather than a msg queue id */
538 return msgctl_nolock(ns
, msqid
, cmd
, version
, buf
);
541 return msgctl_down(ns
, msqid
, cmd
, buf
, version
);
547 static int testmsg(struct msg_msg
*msg
, long type
, int mode
)
553 case SEARCH_LESSEQUAL
:
554 if (msg
->m_type
<= type
)
558 if (msg
->m_type
== type
)
561 case SEARCH_NOTEQUAL
:
562 if (msg
->m_type
!= type
)
569 static inline int pipelined_send(struct msg_queue
*msq
, struct msg_msg
*msg
)
571 struct msg_receiver
*msr
, *t
;
573 list_for_each_entry_safe(msr
, t
, &msq
->q_receivers
, r_list
) {
574 if (testmsg(msg
, msr
->r_msgtype
, msr
->r_mode
) &&
575 !security_msg_queue_msgrcv(msq
, msg
, msr
->r_tsk
,
576 msr
->r_msgtype
, msr
->r_mode
)) {
578 list_del(&msr
->r_list
);
579 if (msr
->r_maxsize
< msg
->m_ts
) {
580 /* initialize pipelined send ordering */
582 wake_up_process(msr
->r_tsk
);
583 smp_mb(); /* see barrier comment below */
584 msr
->r_msg
= ERR_PTR(-E2BIG
);
587 msq
->q_lrpid
= task_pid_vnr(msr
->r_tsk
);
588 msq
->q_rtime
= get_seconds();
589 wake_up_process(msr
->r_tsk
);
591 * Ensure that the wakeup is visible before
592 * setting r_msg, as the receiving end depends
593 * on it. See lockless receive part 1 and 2 in
607 long do_msgsnd(int msqid
, long mtype
, void __user
*mtext
,
608 size_t msgsz
, int msgflg
)
610 struct msg_queue
*msq
;
613 struct ipc_namespace
*ns
;
615 ns
= current
->nsproxy
->ipc_ns
;
617 if (msgsz
> ns
->msg_ctlmax
|| (long) msgsz
< 0 || msqid
< 0)
622 msg
= load_msg(mtext
, msgsz
);
630 msq
= msq_obtain_object_check(ns
, msqid
);
636 ipc_lock_object(&msq
->q_perm
);
642 if (ipcperms(ns
, &msq
->q_perm
, S_IWUGO
))
645 /* raced with RMID? */
646 if (!ipc_valid_object(&msq
->q_perm
)) {
651 err
= security_msg_queue_msgsnd(msq
, msg
, msgflg
);
655 if (msgsz
+ msq
->q_cbytes
<= msq
->q_qbytes
&&
656 1 + msq
->q_qnum
<= msq
->q_qbytes
) {
660 /* queue full, wait: */
661 if (msgflg
& IPC_NOWAIT
) {
666 /* enqueue the sender and prepare to block */
669 if (!ipc_rcu_getref(msq
)) {
674 ipc_unlock_object(&msq
->q_perm
);
679 ipc_lock_object(&msq
->q_perm
);
681 ipc_rcu_putref(msq
, ipc_rcu_free
);
682 /* raced with RMID? */
683 if (!ipc_valid_object(&msq
->q_perm
)) {
690 if (signal_pending(current
)) {
691 err
= -ERESTARTNOHAND
;
696 msq
->q_lspid
= task_tgid_vnr(current
);
697 msq
->q_stime
= get_seconds();
699 if (!pipelined_send(msq
, msg
)) {
700 /* no one is waiting for this message, enqueue it */
701 list_add_tail(&msg
->m_list
, &msq
->q_messages
);
702 msq
->q_cbytes
+= msgsz
;
704 atomic_add(msgsz
, &ns
->msg_bytes
);
705 atomic_inc(&ns
->msg_hdrs
);
712 ipc_unlock_object(&msq
->q_perm
);
720 SYSCALL_DEFINE4(msgsnd
, int, msqid
, struct msgbuf __user
*, msgp
, size_t, msgsz
,
725 if (get_user(mtype
, &msgp
->mtype
))
727 return do_msgsnd(msqid
, mtype
, msgp
->mtext
, msgsz
, msgflg
);
730 static inline int convert_mode(long *msgtyp
, int msgflg
)
732 if (msgflg
& MSG_COPY
)
733 return SEARCH_NUMBER
;
735 * find message of correct type.
736 * msgtyp = 0 => get first.
737 * msgtyp > 0 => get first message of matching type.
738 * msgtyp < 0 => get message with least type must be < abs(msgtype).
744 return SEARCH_LESSEQUAL
;
746 if (msgflg
& MSG_EXCEPT
)
747 return SEARCH_NOTEQUAL
;
751 static long do_msg_fill(void __user
*dest
, struct msg_msg
*msg
, size_t bufsz
)
753 struct msgbuf __user
*msgp
= dest
;
756 if (put_user(msg
->m_type
, &msgp
->mtype
))
759 msgsz
= (bufsz
> msg
->m_ts
) ? msg
->m_ts
: bufsz
;
760 if (store_msg(msgp
->mtext
, msg
, msgsz
))
765 #ifdef CONFIG_CHECKPOINT_RESTORE
767 * This function creates new kernel message structure, large enough to store
768 * bufsz message bytes.
770 static inline struct msg_msg
*prepare_copy(void __user
*buf
, size_t bufsz
)
772 struct msg_msg
*copy
;
775 * Create dummy message to copy real message to.
777 copy
= load_msg(buf
, bufsz
);
783 static inline void free_copy(struct msg_msg
*copy
)
789 static inline struct msg_msg
*prepare_copy(void __user
*buf
, size_t bufsz
)
791 return ERR_PTR(-ENOSYS
);
794 static inline void free_copy(struct msg_msg
*copy
)
799 static struct msg_msg
*find_msg(struct msg_queue
*msq
, long *msgtyp
, int mode
)
801 struct msg_msg
*msg
, *found
= NULL
;
804 list_for_each_entry(msg
, &msq
->q_messages
, m_list
) {
805 if (testmsg(msg
, *msgtyp
, mode
) &&
806 !security_msg_queue_msgrcv(msq
, msg
, current
,
808 if (mode
== SEARCH_LESSEQUAL
&& msg
->m_type
!= 1) {
809 *msgtyp
= msg
->m_type
- 1;
811 } else if (mode
== SEARCH_NUMBER
) {
812 if (*msgtyp
== count
)
820 return found
?: ERR_PTR(-EAGAIN
);
823 long do_msgrcv(int msqid
, void __user
*buf
, size_t bufsz
, long msgtyp
, int msgflg
,
824 long (*msg_handler
)(void __user
*, struct msg_msg
*, size_t))
827 struct msg_queue
*msq
;
828 struct ipc_namespace
*ns
;
829 struct msg_msg
*msg
, *copy
= NULL
;
831 ns
= current
->nsproxy
->ipc_ns
;
833 if (msqid
< 0 || (long) bufsz
< 0)
836 if (msgflg
& MSG_COPY
) {
837 if ((msgflg
& MSG_EXCEPT
) || !(msgflg
& IPC_NOWAIT
))
839 copy
= prepare_copy(buf
, min_t(size_t, bufsz
, ns
->msg_ctlmax
));
841 return PTR_ERR(copy
);
843 mode
= convert_mode(&msgtyp
, msgflg
);
846 msq
= msq_obtain_object_check(ns
, msqid
);
854 struct msg_receiver msr_d
;
856 msg
= ERR_PTR(-EACCES
);
857 if (ipcperms(ns
, &msq
->q_perm
, S_IRUGO
))
860 ipc_lock_object(&msq
->q_perm
);
862 /* raced with RMID? */
863 if (!ipc_valid_object(&msq
->q_perm
)) {
864 msg
= ERR_PTR(-EIDRM
);
868 msg
= find_msg(msq
, &msgtyp
, mode
);
871 * Found a suitable message.
872 * Unlink it from the queue.
874 if ((bufsz
< msg
->m_ts
) && !(msgflg
& MSG_NOERROR
)) {
875 msg
= ERR_PTR(-E2BIG
);
879 * If we are copying, then do not unlink message and do
880 * not update queue parameters.
882 if (msgflg
& MSG_COPY
) {
883 msg
= copy_msg(msg
, copy
);
887 list_del(&msg
->m_list
);
889 msq
->q_rtime
= get_seconds();
890 msq
->q_lrpid
= task_tgid_vnr(current
);
891 msq
->q_cbytes
-= msg
->m_ts
;
892 atomic_sub(msg
->m_ts
, &ns
->msg_bytes
);
893 atomic_dec(&ns
->msg_hdrs
);
894 ss_wakeup(&msq
->q_senders
, 0);
899 /* No message waiting. Wait for a message */
900 if (msgflg
& IPC_NOWAIT
) {
901 msg
= ERR_PTR(-ENOMSG
);
905 list_add_tail(&msr_d
.r_list
, &msq
->q_receivers
);
906 msr_d
.r_tsk
= current
;
907 msr_d
.r_msgtype
= msgtyp
;
909 if (msgflg
& MSG_NOERROR
)
910 msr_d
.r_maxsize
= INT_MAX
;
912 msr_d
.r_maxsize
= bufsz
;
913 msr_d
.r_msg
= ERR_PTR(-EAGAIN
);
914 __set_current_state(TASK_INTERRUPTIBLE
);
916 ipc_unlock_object(&msq
->q_perm
);
920 /* Lockless receive, part 1:
921 * Disable preemption. We don't hold a reference to the queue
922 * and getting a reference would defeat the idea of a lockless
923 * operation, thus the code relies on rcu to guarantee the
925 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
926 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
927 * rcu_read_lock() prevents preemption between reading r_msg
928 * and acquiring the q_perm.lock in ipc_lock_object().
932 /* Lockless receive, part 2:
933 * Wait until pipelined_send or expunge_all are outside of
934 * wake_up_process(). There is a race with exit(), see
935 * ipc/mqueue.c for the details.
937 msg
= (struct msg_msg
*)msr_d
.r_msg
;
938 while (msg
== NULL
) {
940 msg
= (struct msg_msg
*)msr_d
.r_msg
;
943 /* Lockless receive, part 3:
944 * If there is a message or an error then accept it without
947 if (msg
!= ERR_PTR(-EAGAIN
))
950 /* Lockless receive, part 3:
951 * Acquire the queue spinlock.
953 ipc_lock_object(&msq
->q_perm
);
955 /* Lockless receive, part 4:
956 * Repeat test after acquiring the spinlock.
958 msg
= (struct msg_msg
*)msr_d
.r_msg
;
959 if (msg
!= ERR_PTR(-EAGAIN
))
962 list_del(&msr_d
.r_list
);
963 if (signal_pending(current
)) {
964 msg
= ERR_PTR(-ERESTARTNOHAND
);
968 ipc_unlock_object(&msq
->q_perm
);
972 ipc_unlock_object(&msq
->q_perm
);
980 bufsz
= msg_handler(buf
, msg
, bufsz
);
986 SYSCALL_DEFINE5(msgrcv
, int, msqid
, struct msgbuf __user
*, msgp
, size_t, msgsz
,
987 long, msgtyp
, int, msgflg
)
989 return do_msgrcv(msqid
, msgp
, msgsz
, msgtyp
, msgflg
, do_msg_fill
);
993 void msg_init_ns(struct ipc_namespace
*ns
)
995 ns
->msg_ctlmax
= MSGMAX
;
996 ns
->msg_ctlmnb
= MSGMNB
;
997 ns
->msg_ctlmni
= MSGMNI
;
999 atomic_set(&ns
->msg_bytes
, 0);
1000 atomic_set(&ns
->msg_hdrs
, 0);
1001 ipc_init_ids(&ns
->ids
[IPC_MSG_IDS
]);
1004 #ifdef CONFIG_IPC_NS
1005 void msg_exit_ns(struct ipc_namespace
*ns
)
1007 free_ipcs(ns
, &msg_ids(ns
), freeque
);
1008 idr_destroy(&ns
->ids
[IPC_MSG_IDS
].ipcs_idr
);
1012 #ifdef CONFIG_PROC_FS
1013 static int sysvipc_msg_proc_show(struct seq_file
*s
, void *it
)
1015 struct user_namespace
*user_ns
= seq_user_ns(s
);
1016 struct msg_queue
*msq
= it
;
1018 return seq_printf(s
,
1019 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1027 from_kuid_munged(user_ns
, msq
->q_perm
.uid
),
1028 from_kgid_munged(user_ns
, msq
->q_perm
.gid
),
1029 from_kuid_munged(user_ns
, msq
->q_perm
.cuid
),
1030 from_kgid_munged(user_ns
, msq
->q_perm
.cgid
),
1037 void __init
msg_init(void)
1039 msg_init_ns(&init_ipc_ns
);
1041 ipc_init_proc_interface("sysvipc/msg",
1042 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
1043 IPC_MSG_IDS
, sysvipc_msg_proc_show
);
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