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 <asm/uaccess.h>
46 * one msg_receiver structure for each sleeping receiver:
49 struct list_head r_list;
50 struct task_struct *r_tsk;
56 struct msg_msg *volatile r_msg;
59 /* one msg_sender for each sleeping sender */
61 struct list_head list;
62 struct task_struct *tsk;
66 #define SEARCH_EQUAL 2
67 #define SEARCH_NOTEQUAL 3
68 #define SEARCH_LESSEQUAL 4
69 #define SEARCH_NUMBER 5
71 #define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
73 static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
74 static int newque(struct ipc_namespace *, struct ipc_params *);
76 static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
80 * Scale msgmni with the available lowmem size: the memory dedicated to msg
81 * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
82 * Also take into account the number of nsproxies created so far.
83 * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
85 void recompute_msgmni(struct ipc_namespace *ns)
88 unsigned long allowed;
92 allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
94 nb_ns = atomic_read(&nr_ipc_ns);
97 if (allowed < MSGMNI) {
98 ns->msg_ctlmni = MSGMNI;
102 if (allowed > IPCMNI / nb_ns) {
103 ns->msg_ctlmni = IPCMNI / nb_ns;
107 ns->msg_ctlmni = allowed;
110 void msg_init_ns(struct ipc_namespace *ns)
112 ns->msg_ctlmax = MSGMAX;
113 ns->msg_ctlmnb = MSGMNB;
115 recompute_msgmni(ns);
117 atomic_set(&ns->msg_bytes, 0);
118 atomic_set(&ns->msg_hdrs, 0);
119 ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
123 void msg_exit_ns(struct ipc_namespace *ns)
125 free_ipcs(ns, &msg_ids(ns), freeque);
126 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
130 void __init msg_init(void)
132 msg_init_ns(&init_ipc_ns);
134 printk(KERN_INFO "msgmni has been set to %d\n",
135 init_ipc_ns.msg_ctlmni);
137 ipc_init_proc_interface("sysvipc/msg",
138 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
139 IPC_MSG_IDS, sysvipc_msg_proc_show);
142 static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
144 struct kern_ipc_perm *ipcp = ipc_obtain_object(&msg_ids(ns), id);
147 return ERR_CAST(ipcp);
149 return container_of(ipcp, struct msg_queue, q_perm);
152 static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
155 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
158 return ERR_CAST(ipcp);
160 return container_of(ipcp, struct msg_queue, q_perm);
163 static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
165 ipc_rmid(&msg_ids(ns), &s->q_perm);
168 static void msg_rcu_free(struct rcu_head *head)
170 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
171 struct msg_queue *msq = ipc_rcu_to_struct(p);
173 security_msg_queue_free(msq);
178 * newque - Create a new msg queue
180 * @params: ptr to the structure that contains the key and msgflg
182 * Called with msg_ids.rwsem held (writer)
184 static int newque(struct ipc_namespace *ns, struct ipc_params *params)
186 struct msg_queue *msq;
188 key_t key = params->key;
189 int msgflg = params->flg;
191 msq = ipc_rcu_alloc(sizeof(*msq));
195 msq->q_perm.mode = msgflg & S_IRWXUGO;
196 msq->q_perm.key = key;
198 msq->q_perm.security = NULL;
199 retval = security_msg_queue_alloc(msq);
201 ipc_rcu_putref(msq, ipc_rcu_free);
205 /* ipc_addid() locks msq upon success. */
206 id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
208 ipc_rcu_putref(msq, msg_rcu_free);
212 msq->q_stime = msq->q_rtime = 0;
213 msq->q_ctime = get_seconds();
214 msq->q_cbytes = msq->q_qnum = 0;
215 msq->q_qbytes = ns->msg_ctlmnb;
216 msq->q_lspid = msq->q_lrpid = 0;
217 INIT_LIST_HEAD(&msq->q_messages);
218 INIT_LIST_HEAD(&msq->q_receivers);
219 INIT_LIST_HEAD(&msq->q_senders);
221 ipc_unlock_object(&msq->q_perm);
224 return msq->q_perm.id;
227 static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
230 current->state = TASK_INTERRUPTIBLE;
231 list_add_tail(&mss->list, &msq->q_senders);
234 static inline void ss_del(struct msg_sender *mss)
236 if (mss->list.next != NULL)
237 list_del(&mss->list);
240 static void ss_wakeup(struct list_head *h, int kill)
242 struct msg_sender *mss, *t;
244 list_for_each_entry_safe(mss, t, h, list) {
246 mss->list.next = NULL;
247 wake_up_process(mss->tsk);
251 static void expunge_all(struct msg_queue *msq, int res)
253 struct msg_receiver *msr, *t;
255 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
256 msr->r_msg = NULL; /* initialize expunge ordering */
257 wake_up_process(msr->r_tsk);
259 * Ensure that the wakeup is visible before setting r_msg as
260 * the receiving end depends on it: either spinning on a nil,
261 * or dealing with -EAGAIN cases. See lockless receive part 1
262 * and 2 in do_msgrcv().
265 msr->r_msg = ERR_PTR(res);
270 * freeque() wakes up waiters on the sender and receiver waiting queue,
271 * removes the message queue from message queue ID IDR, and cleans up all the
272 * messages associated with this queue.
274 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
275 * before freeque() is called. msg_ids.rwsem remains locked on exit.
277 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
279 struct msg_msg *msg, *t;
280 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
282 expunge_all(msq, -EIDRM);
283 ss_wakeup(&msq->q_senders, 1);
285 ipc_unlock_object(&msq->q_perm);
288 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
289 atomic_dec(&ns->msg_hdrs);
292 atomic_sub(msq->q_cbytes, &ns->msg_bytes);
293 ipc_rcu_putref(msq, msg_rcu_free);
297 * Called with msg_ids.rwsem and ipcp locked.
299 static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
301 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
303 return security_msg_queue_associate(msq, msgflg);
306 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
308 struct ipc_namespace *ns;
309 static const struct ipc_ops msg_ops = {
311 .associate = msg_security,
313 struct ipc_params msg_params;
315 ns = current->nsproxy->ipc_ns;
317 msg_params.key = key;
318 msg_params.flg = msgflg;
320 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
323 static inline unsigned long
324 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
328 return copy_to_user(buf, in, sizeof(*in));
333 memset(&out, 0, sizeof(out));
335 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
337 out.msg_stime = in->msg_stime;
338 out.msg_rtime = in->msg_rtime;
339 out.msg_ctime = in->msg_ctime;
341 if (in->msg_cbytes > USHRT_MAX)
342 out.msg_cbytes = USHRT_MAX;
344 out.msg_cbytes = in->msg_cbytes;
345 out.msg_lcbytes = in->msg_cbytes;
347 if (in->msg_qnum > USHRT_MAX)
348 out.msg_qnum = USHRT_MAX;
350 out.msg_qnum = in->msg_qnum;
352 if (in->msg_qbytes > USHRT_MAX)
353 out.msg_qbytes = USHRT_MAX;
355 out.msg_qbytes = in->msg_qbytes;
356 out.msg_lqbytes = in->msg_qbytes;
358 out.msg_lspid = in->msg_lspid;
359 out.msg_lrpid = in->msg_lrpid;
361 return copy_to_user(buf, &out, sizeof(out));
368 static inline unsigned long
369 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
373 if (copy_from_user(out, buf, sizeof(*out)))
378 struct msqid_ds tbuf_old;
380 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
383 out->msg_perm.uid = tbuf_old.msg_perm.uid;
384 out->msg_perm.gid = tbuf_old.msg_perm.gid;
385 out->msg_perm.mode = tbuf_old.msg_perm.mode;
387 if (tbuf_old.msg_qbytes == 0)
388 out->msg_qbytes = tbuf_old.msg_lqbytes;
390 out->msg_qbytes = tbuf_old.msg_qbytes;
400 * This function handles some msgctl commands which require the rwsem
401 * to be held in write mode.
402 * NOTE: no locks must be held, the rwsem is taken inside this function.
404 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
405 struct msqid_ds __user *buf, int version)
407 struct kern_ipc_perm *ipcp;
408 struct msqid64_ds uninitialized_var(msqid64);
409 struct msg_queue *msq;
412 if (cmd == IPC_SET) {
413 if (copy_msqid_from_user(&msqid64, buf, version))
417 down_write(&msg_ids(ns).rwsem);
420 ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
421 &msqid64.msg_perm, msqid64.msg_qbytes);
427 msq = container_of(ipcp, struct msg_queue, q_perm);
429 err = security_msg_queue_msgctl(msq, cmd);
435 ipc_lock_object(&msq->q_perm);
436 /* freeque unlocks the ipc object and rcu */
440 if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
441 !capable(CAP_SYS_RESOURCE)) {
446 ipc_lock_object(&msq->q_perm);
447 err = ipc_update_perm(&msqid64.msg_perm, ipcp);
451 msq->q_qbytes = msqid64.msg_qbytes;
453 msq->q_ctime = get_seconds();
454 /* sleeping receivers might be excluded by
455 * stricter permissions.
457 expunge_all(msq, -EAGAIN);
458 /* sleeping senders might be able to send
459 * due to a larger queue size.
461 ss_wakeup(&msq->q_senders, 0);
469 ipc_unlock_object(&msq->q_perm);
473 up_write(&msg_ids(ns).rwsem);
477 static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
478 int cmd, int version, void __user *buf)
481 struct msg_queue *msq;
487 struct msginfo msginfo;
494 * We must not return kernel stack data.
495 * due to padding, it's not enough
496 * to set all member fields.
498 err = security_msg_queue_msgctl(NULL, cmd);
502 memset(&msginfo, 0, sizeof(msginfo));
503 msginfo.msgmni = ns->msg_ctlmni;
504 msginfo.msgmax = ns->msg_ctlmax;
505 msginfo.msgmnb = ns->msg_ctlmnb;
506 msginfo.msgssz = MSGSSZ;
507 msginfo.msgseg = MSGSEG;
508 down_read(&msg_ids(ns).rwsem);
509 if (cmd == MSG_INFO) {
510 msginfo.msgpool = msg_ids(ns).in_use;
511 msginfo.msgmap = atomic_read(&ns->msg_hdrs);
512 msginfo.msgtql = atomic_read(&ns->msg_bytes);
514 msginfo.msgmap = MSGMAP;
515 msginfo.msgpool = MSGPOOL;
516 msginfo.msgtql = MSGTQL;
518 max_id = ipc_get_maxid(&msg_ids(ns));
519 up_read(&msg_ids(ns).rwsem);
520 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
522 return (max_id < 0) ? 0 : max_id;
528 struct msqid64_ds tbuf;
534 memset(&tbuf, 0, sizeof(tbuf));
537 if (cmd == MSG_STAT) {
538 msq = msq_obtain_object(ns, msqid);
543 success_return = msq->q_perm.id;
545 msq = msq_obtain_object_check(ns, msqid);
554 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
557 err = security_msg_queue_msgctl(msq, cmd);
561 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
562 tbuf.msg_stime = msq->q_stime;
563 tbuf.msg_rtime = msq->q_rtime;
564 tbuf.msg_ctime = msq->q_ctime;
565 tbuf.msg_cbytes = msq->q_cbytes;
566 tbuf.msg_qnum = msq->q_qnum;
567 tbuf.msg_qbytes = msq->q_qbytes;
568 tbuf.msg_lspid = msq->q_lspid;
569 tbuf.msg_lrpid = msq->q_lrpid;
572 if (copy_msqid_to_user(buf, &tbuf, version))
574 return success_return;
587 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
590 struct ipc_namespace *ns;
592 if (msqid < 0 || cmd < 0)
595 version = ipc_parse_version(&cmd);
596 ns = current->nsproxy->ipc_ns;
601 case MSG_STAT: /* msqid is an index rather than a msg queue id */
603 return msgctl_nolock(ns, msqid, cmd, version, buf);
606 return msgctl_down(ns, msqid, cmd, buf, version);
612 static int testmsg(struct msg_msg *msg, long type, int mode)
619 case SEARCH_LESSEQUAL:
620 if (msg->m_type <= type)
624 if (msg->m_type == type)
627 case SEARCH_NOTEQUAL:
628 if (msg->m_type != type)
635 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
637 struct msg_receiver *msr, *t;
639 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
640 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
641 !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
642 msr->r_msgtype, msr->r_mode)) {
644 list_del(&msr->r_list);
645 if (msr->r_maxsize < msg->m_ts) {
646 /* initialize pipelined send ordering */
648 wake_up_process(msr->r_tsk);
649 smp_mb(); /* see barrier comment below */
650 msr->r_msg = ERR_PTR(-E2BIG);
653 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
654 msq->q_rtime = get_seconds();
655 wake_up_process(msr->r_tsk);
657 * Ensure that the wakeup is visible before
658 * setting r_msg, as the receiving end depends
659 * on it. See lockless receive part 1 and 2 in
673 long do_msgsnd(int msqid, long mtype, void __user *mtext,
674 size_t msgsz, int msgflg)
676 struct msg_queue *msq;
679 struct ipc_namespace *ns;
681 ns = current->nsproxy->ipc_ns;
683 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
688 msg = load_msg(mtext, msgsz);
696 msq = msq_obtain_object_check(ns, msqid);
702 ipc_lock_object(&msq->q_perm);
708 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
711 /* raced with RMID? */
712 if (!ipc_valid_object(&msq->q_perm)) {
717 err = security_msg_queue_msgsnd(msq, msg, msgflg);
721 if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
722 1 + msq->q_qnum <= msq->q_qbytes) {
726 /* queue full, wait: */
727 if (msgflg & IPC_NOWAIT) {
732 /* enqueue the sender and prepare to block */
735 if (!ipc_rcu_getref(msq)) {
740 ipc_unlock_object(&msq->q_perm);
745 ipc_lock_object(&msq->q_perm);
747 ipc_rcu_putref(msq, ipc_rcu_free);
748 /* raced with RMID? */
749 if (!ipc_valid_object(&msq->q_perm)) {
756 if (signal_pending(current)) {
757 err = -ERESTARTNOHAND;
762 msq->q_lspid = task_tgid_vnr(current);
763 msq->q_stime = get_seconds();
765 if (!pipelined_send(msq, msg)) {
766 /* no one is waiting for this message, enqueue it */
767 list_add_tail(&msg->m_list, &msq->q_messages);
768 msq->q_cbytes += msgsz;
770 atomic_add(msgsz, &ns->msg_bytes);
771 atomic_inc(&ns->msg_hdrs);
778 ipc_unlock_object(&msq->q_perm);
786 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
791 if (get_user(mtype, &msgp->mtype))
793 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
796 static inline int convert_mode(long *msgtyp, int msgflg)
798 if (msgflg & MSG_COPY)
799 return SEARCH_NUMBER;
801 * find message of correct type.
802 * msgtyp = 0 => get first.
803 * msgtyp > 0 => get first message of matching type.
804 * msgtyp < 0 => get message with least type must be < abs(msgtype).
810 return SEARCH_LESSEQUAL;
812 if (msgflg & MSG_EXCEPT)
813 return SEARCH_NOTEQUAL;
817 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
819 struct msgbuf __user *msgp = dest;
822 if (put_user(msg->m_type, &msgp->mtype))
825 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
826 if (store_msg(msgp->mtext, msg, msgsz))
831 #ifdef CONFIG_CHECKPOINT_RESTORE
833 * This function creates new kernel message structure, large enough to store
834 * bufsz message bytes.
836 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
838 struct msg_msg *copy;
841 * Create dummy message to copy real message to.
843 copy = load_msg(buf, bufsz);
849 static inline void free_copy(struct msg_msg *copy)
855 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
857 return ERR_PTR(-ENOSYS);
860 static inline void free_copy(struct msg_msg *copy)
865 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
867 struct msg_msg *msg, *found = NULL;
870 list_for_each_entry(msg, &msq->q_messages, m_list) {
871 if (testmsg(msg, *msgtyp, mode) &&
872 !security_msg_queue_msgrcv(msq, msg, current,
874 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
875 *msgtyp = msg->m_type - 1;
877 } else if (mode == SEARCH_NUMBER) {
878 if (*msgtyp == count)
886 return found ?: ERR_PTR(-EAGAIN);
889 long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
890 long (*msg_handler)(void __user *, struct msg_msg *, size_t))
893 struct msg_queue *msq;
894 struct ipc_namespace *ns;
895 struct msg_msg *msg, *copy = NULL;
897 ns = current->nsproxy->ipc_ns;
899 if (msqid < 0 || (long) bufsz < 0)
902 if (msgflg & MSG_COPY) {
903 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
905 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
907 return PTR_ERR(copy);
909 mode = convert_mode(&msgtyp, msgflg);
912 msq = msq_obtain_object_check(ns, msqid);
920 struct msg_receiver msr_d;
922 msg = ERR_PTR(-EACCES);
923 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
926 ipc_lock_object(&msq->q_perm);
928 /* raced with RMID? */
929 if (!ipc_valid_object(&msq->q_perm)) {
930 msg = ERR_PTR(-EIDRM);
934 msg = find_msg(msq, &msgtyp, mode);
937 * Found a suitable message.
938 * Unlink it from the queue.
940 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
941 msg = ERR_PTR(-E2BIG);
945 * If we are copying, then do not unlink message and do
946 * not update queue parameters.
948 if (msgflg & MSG_COPY) {
949 msg = copy_msg(msg, copy);
953 list_del(&msg->m_list);
955 msq->q_rtime = get_seconds();
956 msq->q_lrpid = task_tgid_vnr(current);
957 msq->q_cbytes -= msg->m_ts;
958 atomic_sub(msg->m_ts, &ns->msg_bytes);
959 atomic_dec(&ns->msg_hdrs);
960 ss_wakeup(&msq->q_senders, 0);
965 /* No message waiting. Wait for a message */
966 if (msgflg & IPC_NOWAIT) {
967 msg = ERR_PTR(-ENOMSG);
971 list_add_tail(&msr_d.r_list, &msq->q_receivers);
972 msr_d.r_tsk = current;
973 msr_d.r_msgtype = msgtyp;
975 if (msgflg & MSG_NOERROR)
976 msr_d.r_maxsize = INT_MAX;
978 msr_d.r_maxsize = bufsz;
979 msr_d.r_msg = ERR_PTR(-EAGAIN);
980 current->state = TASK_INTERRUPTIBLE;
982 ipc_unlock_object(&msq->q_perm);
986 /* Lockless receive, part 1:
987 * Disable preemption. We don't hold a reference to the queue
988 * and getting a reference would defeat the idea of a lockless
989 * operation, thus the code relies on rcu to guarantee the
991 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
992 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
993 * rcu_read_lock() prevents preemption between reading r_msg
994 * and acquiring the q_perm.lock in ipc_lock_object().
998 /* Lockless receive, part 2:
999 * Wait until pipelined_send or expunge_all are outside of
1000 * wake_up_process(). There is a race with exit(), see
1001 * ipc/mqueue.c for the details.
1003 msg = (struct msg_msg *)msr_d.r_msg;
1004 while (msg == NULL) {
1006 msg = (struct msg_msg *)msr_d.r_msg;
1009 /* Lockless receive, part 3:
1010 * If there is a message or an error then accept it without
1013 if (msg != ERR_PTR(-EAGAIN))
1016 /* Lockless receive, part 3:
1017 * Acquire the queue spinlock.
1019 ipc_lock_object(&msq->q_perm);
1021 /* Lockless receive, part 4:
1022 * Repeat test after acquiring the spinlock.
1024 msg = (struct msg_msg *)msr_d.r_msg;
1025 if (msg != ERR_PTR(-EAGAIN))
1028 list_del(&msr_d.r_list);
1029 if (signal_pending(current)) {
1030 msg = ERR_PTR(-ERESTARTNOHAND);
1034 ipc_unlock_object(&msq->q_perm);
1038 ipc_unlock_object(&msq->q_perm);
1043 return PTR_ERR(msg);
1046 bufsz = msg_handler(buf, msg, bufsz);
1052 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1053 long, msgtyp, int, msgflg)
1055 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1058 #ifdef CONFIG_PROC_FS
1059 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1061 struct user_namespace *user_ns = seq_user_ns(s);
1062 struct msg_queue *msq = it;
1064 return seq_printf(s,
1065 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1073 from_kuid_munged(user_ns, msq->q_perm.uid),
1074 from_kgid_munged(user_ns, msq->q_perm.gid),
1075 from_kuid_munged(user_ns, msq->q_perm.cuid),
1076 from_kgid_munged(user_ns, msq->q_perm.cgid),