Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/ipc/msg.c b/ipc/msg.c
new file mode 100644
index 0000000..27e516f
--- /dev/null
+++ b/ipc/msg.c
@@ -0,0 +1,862 @@
+/*
+ * linux/ipc/msg.c
+ * Copyright (C) 1992 Krishna Balasubramanian
+ *
+ * Removed all the remaining kerneld mess
+ * Catch the -EFAULT stuff properly
+ * Use GFP_KERNEL for messages as in 1.2
+ * Fixed up the unchecked user space derefs
+ * Copyright (C) 1998 Alan Cox & Andi Kleen
+ *
+ * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
+ *
+ * mostly rewritten, threaded and wake-one semantics added
+ * MSGMAX limit removed, sysctl's added
+ * (c) 1999 Manfred Spraul <manfreds@colorfullife.com>
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/msg.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/list.h>
+#include <linux/security.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <asm/current.h>
+#include <asm/uaccess.h>
+#include "util.h"
+
+/* sysctl: */
+int msg_ctlmax = MSGMAX;
+int msg_ctlmnb = MSGMNB;
+int msg_ctlmni = MSGMNI;
+
+/* one msg_receiver structure for each sleeping receiver */
+struct msg_receiver {
+ struct list_head r_list;
+ struct task_struct* r_tsk;
+
+ int r_mode;
+ long r_msgtype;
+ long r_maxsize;
+
+ struct msg_msg* volatile r_msg;
+};
+
+/* one msg_sender for each sleeping sender */
+struct msg_sender {
+ struct list_head list;
+ struct task_struct* tsk;
+};
+
+#define SEARCH_ANY 1
+#define SEARCH_EQUAL 2
+#define SEARCH_NOTEQUAL 3
+#define SEARCH_LESSEQUAL 4
+
+static atomic_t msg_bytes = ATOMIC_INIT(0);
+static atomic_t msg_hdrs = ATOMIC_INIT(0);
+
+static struct ipc_ids msg_ids;
+
+#define msg_lock(id) ((struct msg_queue*)ipc_lock(&msg_ids,id))
+#define msg_unlock(msq) ipc_unlock(&(msq)->q_perm)
+#define msg_rmid(id) ((struct msg_queue*)ipc_rmid(&msg_ids,id))
+#define msg_checkid(msq, msgid) \
+ ipc_checkid(&msg_ids,&msq->q_perm,msgid)
+#define msg_buildid(id, seq) \
+ ipc_buildid(&msg_ids, id, seq)
+
+static void freeque (struct msg_queue *msq, int id);
+static int newque (key_t key, int msgflg);
+#ifdef CONFIG_PROC_FS
+static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
+#endif
+
+void __init msg_init (void)
+{
+ ipc_init_ids(&msg_ids,msg_ctlmni);
+
+#ifdef CONFIG_PROC_FS
+ create_proc_read_entry("sysvipc/msg", 0, NULL, sysvipc_msg_read_proc, NULL);
+#endif
+}
+
+static int newque (key_t key, int msgflg)
+{
+ int id;
+ int retval;
+ struct msg_queue *msq;
+
+ msq = ipc_rcu_alloc(sizeof(*msq));
+ if (!msq)
+ return -ENOMEM;
+
+ msq->q_perm.mode = (msgflg & S_IRWXUGO);
+ msq->q_perm.key = key;
+
+ msq->q_perm.security = NULL;
+ retval = security_msg_queue_alloc(msq);
+ if (retval) {
+ ipc_rcu_putref(msq);
+ return retval;
+ }
+
+ id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni);
+ if(id == -1) {
+ security_msg_queue_free(msq);
+ ipc_rcu_putref(msq);
+ return -ENOSPC;
+ }
+
+ msq->q_stime = msq->q_rtime = 0;
+ msq->q_ctime = get_seconds();
+ msq->q_cbytes = msq->q_qnum = 0;
+ msq->q_qbytes = msg_ctlmnb;
+ msq->q_lspid = msq->q_lrpid = 0;
+ INIT_LIST_HEAD(&msq->q_messages);
+ INIT_LIST_HEAD(&msq->q_receivers);
+ INIT_LIST_HEAD(&msq->q_senders);
+ msg_unlock(msq);
+
+ return msg_buildid(id,msq->q_perm.seq);
+}
+
+static inline void ss_add(struct msg_queue* msq, struct msg_sender* mss)
+{
+ mss->tsk=current;
+ current->state=TASK_INTERRUPTIBLE;
+ list_add_tail(&mss->list,&msq->q_senders);
+}
+
+static inline void ss_del(struct msg_sender* mss)
+{
+ if(mss->list.next != NULL)
+ list_del(&mss->list);
+}
+
+static void ss_wakeup(struct list_head* h, int kill)
+{
+ struct list_head *tmp;
+
+ tmp = h->next;
+ while (tmp != h) {
+ struct msg_sender* mss;
+
+ mss = list_entry(tmp,struct msg_sender,list);
+ tmp = tmp->next;
+ if(kill)
+ mss->list.next=NULL;
+ wake_up_process(mss->tsk);
+ }
+}
+
+static void expunge_all(struct msg_queue* msq, int res)
+{
+ struct list_head *tmp;
+
+ tmp = msq->q_receivers.next;
+ while (tmp != &msq->q_receivers) {
+ struct msg_receiver* msr;
+
+ msr = list_entry(tmp,struct msg_receiver,r_list);
+ tmp = tmp->next;
+ msr->r_msg = NULL;
+ wake_up_process(msr->r_tsk);
+ smp_mb();
+ msr->r_msg = ERR_PTR(res);
+ }
+}
+/*
+ * freeque() wakes up waiters on the sender and receiver waiting queue,
+ * removes the message queue from message queue ID
+ * array, and cleans up all the messages associated with this queue.
+ *
+ * msg_ids.sem and the spinlock for this message queue is hold
+ * before freeque() is called. msg_ids.sem remains locked on exit.
+ */
+static void freeque (struct msg_queue *msq, int id)
+{
+ struct list_head *tmp;
+
+ expunge_all(msq,-EIDRM);
+ ss_wakeup(&msq->q_senders,1);
+ msq = msg_rmid(id);
+ msg_unlock(msq);
+
+ tmp = msq->q_messages.next;
+ while(tmp != &msq->q_messages) {
+ struct msg_msg* msg = list_entry(tmp,struct msg_msg,m_list);
+ tmp = tmp->next;
+ atomic_dec(&msg_hdrs);
+ free_msg(msg);
+ }
+ atomic_sub(msq->q_cbytes, &msg_bytes);
+ security_msg_queue_free(msq);
+ ipc_rcu_putref(msq);
+}
+
+asmlinkage long sys_msgget (key_t key, int msgflg)
+{
+ int id, ret = -EPERM;
+ struct msg_queue *msq;
+
+ down(&msg_ids.sem);
+ if (key == IPC_PRIVATE)
+ ret = newque(key, msgflg);
+ else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */
+ if (!(msgflg & IPC_CREAT))
+ ret = -ENOENT;
+ else
+ ret = newque(key, msgflg);
+ } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) {
+ ret = -EEXIST;
+ } else {
+ msq = msg_lock(id);
+ if(msq==NULL)
+ BUG();
+ if (ipcperms(&msq->q_perm, msgflg))
+ ret = -EACCES;
+ else {
+ int qid = msg_buildid(id, msq->q_perm.seq);
+ ret = security_msg_queue_associate(msq, msgflg);
+ if (!ret)
+ ret = qid;
+ }
+ msg_unlock(msq);
+ }
+ up(&msg_ids.sem);
+ return ret;
+}
+
+static inline unsigned long copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
+{
+ switch(version) {
+ case IPC_64:
+ return copy_to_user (buf, in, sizeof(*in));
+ case IPC_OLD:
+ {
+ struct msqid_ds out;
+
+ memset(&out,0,sizeof(out));
+
+ ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
+
+ out.msg_stime = in->msg_stime;
+ out.msg_rtime = in->msg_rtime;
+ out.msg_ctime = in->msg_ctime;
+
+ if(in->msg_cbytes > USHRT_MAX)
+ out.msg_cbytes = USHRT_MAX;
+ else
+ out.msg_cbytes = in->msg_cbytes;
+ out.msg_lcbytes = in->msg_cbytes;
+
+ if(in->msg_qnum > USHRT_MAX)
+ out.msg_qnum = USHRT_MAX;
+ else
+ out.msg_qnum = in->msg_qnum;
+
+ if(in->msg_qbytes > USHRT_MAX)
+ out.msg_qbytes = USHRT_MAX;
+ else
+ out.msg_qbytes = in->msg_qbytes;
+ out.msg_lqbytes = in->msg_qbytes;
+
+ out.msg_lspid = in->msg_lspid;
+ out.msg_lrpid = in->msg_lrpid;
+
+ return copy_to_user (buf, &out, sizeof(out));
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+struct msq_setbuf {
+ unsigned long qbytes;
+ uid_t uid;
+ gid_t gid;
+ mode_t mode;
+};
+
+static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version)
+{
+ switch(version) {
+ case IPC_64:
+ {
+ struct msqid64_ds tbuf;
+
+ if (copy_from_user (&tbuf, buf, sizeof (tbuf)))
+ return -EFAULT;
+
+ out->qbytes = tbuf.msg_qbytes;
+ out->uid = tbuf.msg_perm.uid;
+ out->gid = tbuf.msg_perm.gid;
+ out->mode = tbuf.msg_perm.mode;
+
+ return 0;
+ }
+ case IPC_OLD:
+ {
+ struct msqid_ds tbuf_old;
+
+ if (copy_from_user (&tbuf_old, buf, sizeof (tbuf_old)))
+ return -EFAULT;
+
+ out->uid = tbuf_old.msg_perm.uid;
+ out->gid = tbuf_old.msg_perm.gid;
+ out->mode = tbuf_old.msg_perm.mode;
+
+ if(tbuf_old.msg_qbytes == 0)
+ out->qbytes = tbuf_old.msg_lqbytes;
+ else
+ out->qbytes = tbuf_old.msg_qbytes;
+
+ return 0;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds __user *buf)
+{
+ int err, version;
+ struct msg_queue *msq;
+ struct msq_setbuf setbuf;
+ struct kern_ipc_perm *ipcp;
+
+ if (msqid < 0 || cmd < 0)
+ return -EINVAL;
+
+ version = ipc_parse_version(&cmd);
+
+ switch (cmd) {
+ case IPC_INFO:
+ case MSG_INFO:
+ {
+ struct msginfo msginfo;
+ int max_id;
+ if (!buf)
+ return -EFAULT;
+ /* We must not return kernel stack data.
+ * due to padding, it's not enough
+ * to set all member fields.
+ */
+
+ err = security_msg_queue_msgctl(NULL, cmd);
+ if (err)
+ return err;
+
+ memset(&msginfo,0,sizeof(msginfo));
+ msginfo.msgmni = msg_ctlmni;
+ msginfo.msgmax = msg_ctlmax;
+ msginfo.msgmnb = msg_ctlmnb;
+ msginfo.msgssz = MSGSSZ;
+ msginfo.msgseg = MSGSEG;
+ down(&msg_ids.sem);
+ if (cmd == MSG_INFO) {
+ msginfo.msgpool = msg_ids.in_use;
+ msginfo.msgmap = atomic_read(&msg_hdrs);
+ msginfo.msgtql = atomic_read(&msg_bytes);
+ } else {
+ msginfo.msgmap = MSGMAP;
+ msginfo.msgpool = MSGPOOL;
+ msginfo.msgtql = MSGTQL;
+ }
+ max_id = msg_ids.max_id;
+ up(&msg_ids.sem);
+ if (copy_to_user (buf, &msginfo, sizeof(struct msginfo)))
+ return -EFAULT;
+ return (max_id < 0) ? 0: max_id;
+ }
+ case MSG_STAT:
+ case IPC_STAT:
+ {
+ struct msqid64_ds tbuf;
+ int success_return;
+ if (!buf)
+ return -EFAULT;
+ if(cmd == MSG_STAT && msqid >= msg_ids.entries->size)
+ return -EINVAL;
+
+ memset(&tbuf,0,sizeof(tbuf));
+
+ msq = msg_lock(msqid);
+ if (msq == NULL)
+ return -EINVAL;
+
+ if(cmd == MSG_STAT) {
+ success_return = msg_buildid(msqid, msq->q_perm.seq);
+ } else {
+ err = -EIDRM;
+ if (msg_checkid(msq,msqid))
+ goto out_unlock;
+ success_return = 0;
+ }
+ err = -EACCES;
+ if (ipcperms (&msq->q_perm, S_IRUGO))
+ goto out_unlock;
+
+ err = security_msg_queue_msgctl(msq, cmd);
+ if (err)
+ goto out_unlock;
+
+ kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
+ tbuf.msg_stime = msq->q_stime;
+ tbuf.msg_rtime = msq->q_rtime;
+ tbuf.msg_ctime = msq->q_ctime;
+ tbuf.msg_cbytes = msq->q_cbytes;
+ tbuf.msg_qnum = msq->q_qnum;
+ tbuf.msg_qbytes = msq->q_qbytes;
+ tbuf.msg_lspid = msq->q_lspid;
+ tbuf.msg_lrpid = msq->q_lrpid;
+ msg_unlock(msq);
+ if (copy_msqid_to_user(buf, &tbuf, version))
+ return -EFAULT;
+ return success_return;
+ }
+ case IPC_SET:
+ if (!buf)
+ return -EFAULT;
+ if (copy_msqid_from_user (&setbuf, buf, version))
+ return -EFAULT;
+ if ((err = audit_ipc_perms(setbuf.qbytes, setbuf.uid, setbuf.gid, setbuf.mode)))
+ return err;
+ break;
+ case IPC_RMID:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ down(&msg_ids.sem);
+ msq = msg_lock(msqid);
+ err=-EINVAL;
+ if (msq == NULL)
+ goto out_up;
+
+ err = -EIDRM;
+ if (msg_checkid(msq,msqid))
+ goto out_unlock_up;
+ ipcp = &msq->q_perm;
+ err = -EPERM;
+ if (current->euid != ipcp->cuid &&
+ current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN))
+ /* We _could_ check for CAP_CHOWN above, but we don't */
+ goto out_unlock_up;
+
+ err = security_msg_queue_msgctl(msq, cmd);
+ if (err)
+ goto out_unlock_up;
+
+ switch (cmd) {
+ case IPC_SET:
+ {
+ err = -EPERM;
+ if (setbuf.qbytes > msg_ctlmnb && !capable(CAP_SYS_RESOURCE))
+ goto out_unlock_up;
+
+ msq->q_qbytes = setbuf.qbytes;
+
+ ipcp->uid = setbuf.uid;
+ ipcp->gid = setbuf.gid;
+ ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
+ (S_IRWXUGO & setbuf.mode);
+ msq->q_ctime = get_seconds();
+ /* sleeping receivers might be excluded by
+ * stricter permissions.
+ */
+ expunge_all(msq,-EAGAIN);
+ /* sleeping senders might be able to send
+ * due to a larger queue size.
+ */
+ ss_wakeup(&msq->q_senders,0);
+ msg_unlock(msq);
+ break;
+ }
+ case IPC_RMID:
+ freeque (msq, msqid);
+ break;
+ }
+ err = 0;
+out_up:
+ up(&msg_ids.sem);
+ return err;
+out_unlock_up:
+ msg_unlock(msq);
+ goto out_up;
+out_unlock:
+ msg_unlock(msq);
+ return err;
+}
+
+static int testmsg(struct msg_msg* msg,long type,int mode)
+{
+ switch(mode)
+ {
+ case SEARCH_ANY:
+ return 1;
+ case SEARCH_LESSEQUAL:
+ if(msg->m_type <=type)
+ return 1;
+ break;
+ case SEARCH_EQUAL:
+ if(msg->m_type == type)
+ return 1;
+ break;
+ case SEARCH_NOTEQUAL:
+ if(msg->m_type != type)
+ return 1;
+ break;
+ }
+ return 0;
+}
+
+static inline int pipelined_send(struct msg_queue* msq, struct msg_msg* msg)
+{
+ struct list_head* tmp;
+
+ tmp = msq->q_receivers.next;
+ while (tmp != &msq->q_receivers) {
+ struct msg_receiver* msr;
+ msr = list_entry(tmp,struct msg_receiver,r_list);
+ tmp = tmp->next;
+ if(testmsg(msg,msr->r_msgtype,msr->r_mode) &&
+ !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, msr->r_msgtype, msr->r_mode)) {
+ list_del(&msr->r_list);
+ if(msr->r_maxsize < msg->m_ts) {
+ msr->r_msg = NULL;
+ wake_up_process(msr->r_tsk);
+ smp_mb();
+ msr->r_msg = ERR_PTR(-E2BIG);
+ } else {
+ msr->r_msg = NULL;
+ msq->q_lrpid = msr->r_tsk->pid;
+ msq->q_rtime = get_seconds();
+ wake_up_process(msr->r_tsk);
+ smp_mb();
+ msr->r_msg = msg;
+ return 1;
+ }
+ }
+ }
+ return 0;
+}
+
+asmlinkage long sys_msgsnd (int msqid, struct msgbuf __user *msgp, size_t msgsz, int msgflg)
+{
+ struct msg_queue *msq;
+ struct msg_msg *msg;
+ long mtype;
+ int err;
+
+ if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0)
+ return -EINVAL;
+ if (get_user(mtype, &msgp->mtype))
+ return -EFAULT;
+ if (mtype < 1)
+ return -EINVAL;
+
+ msg = load_msg(msgp->mtext, msgsz);
+ if(IS_ERR(msg))
+ return PTR_ERR(msg);
+
+ msg->m_type = mtype;
+ msg->m_ts = msgsz;
+
+ msq = msg_lock(msqid);
+ err=-EINVAL;
+ if(msq==NULL)
+ goto out_free;
+
+ err= -EIDRM;
+ if (msg_checkid(msq,msqid))
+ goto out_unlock_free;
+
+ for (;;) {
+ struct msg_sender s;
+
+ err=-EACCES;
+ if (ipcperms(&msq->q_perm, S_IWUGO))
+ goto out_unlock_free;
+
+ err = security_msg_queue_msgsnd(msq, msg, msgflg);
+ if (err)
+ goto out_unlock_free;
+
+ if(msgsz + msq->q_cbytes <= msq->q_qbytes &&
+ 1 + msq->q_qnum <= msq->q_qbytes) {
+ break;
+ }
+
+ /* queue full, wait: */
+ if(msgflg&IPC_NOWAIT) {
+ err=-EAGAIN;
+ goto out_unlock_free;
+ }
+ ss_add(msq, &s);
+ ipc_rcu_getref(msq);
+ msg_unlock(msq);
+ schedule();
+
+ ipc_lock_by_ptr(&msq->q_perm);
+ ipc_rcu_putref(msq);
+ if (msq->q_perm.deleted) {
+ err = -EIDRM;
+ goto out_unlock_free;
+ }
+ ss_del(&s);
+
+ if (signal_pending(current)) {
+ err=-ERESTARTNOHAND;
+ goto out_unlock_free;
+ }
+ }
+
+ msq->q_lspid = current->tgid;
+ msq->q_stime = get_seconds();
+
+ if(!pipelined_send(msq,msg)) {
+ /* noone is waiting for this message, enqueue it */
+ list_add_tail(&msg->m_list,&msq->q_messages);
+ msq->q_cbytes += msgsz;
+ msq->q_qnum++;
+ atomic_add(msgsz,&msg_bytes);
+ atomic_inc(&msg_hdrs);
+ }
+
+ err = 0;
+ msg = NULL;
+
+out_unlock_free:
+ msg_unlock(msq);
+out_free:
+ if(msg!=NULL)
+ free_msg(msg);
+ return err;
+}
+
+static inline int convert_mode(long* msgtyp, int msgflg)
+{
+ /*
+ * find message of correct type.
+ * msgtyp = 0 => get first.
+ * msgtyp > 0 => get first message of matching type.
+ * msgtyp < 0 => get message with least type must be < abs(msgtype).
+ */
+ if(*msgtyp==0)
+ return SEARCH_ANY;
+ if(*msgtyp<0) {
+ *msgtyp=-(*msgtyp);
+ return SEARCH_LESSEQUAL;
+ }
+ if(msgflg & MSG_EXCEPT)
+ return SEARCH_NOTEQUAL;
+ return SEARCH_EQUAL;
+}
+
+asmlinkage long sys_msgrcv (int msqid, struct msgbuf __user *msgp, size_t msgsz,
+ long msgtyp, int msgflg)
+{
+ struct msg_queue *msq;
+ struct msg_msg *msg;
+ int mode;
+
+ if (msqid < 0 || (long) msgsz < 0)
+ return -EINVAL;
+ mode = convert_mode(&msgtyp,msgflg);
+
+ msq = msg_lock(msqid);
+ if(msq==NULL)
+ return -EINVAL;
+
+ msg = ERR_PTR(-EIDRM);
+ if (msg_checkid(msq,msqid))
+ goto out_unlock;
+
+ for (;;) {
+ struct msg_receiver msr_d;
+ struct list_head* tmp;
+
+ msg = ERR_PTR(-EACCES);
+ if (ipcperms (&msq->q_perm, S_IRUGO))
+ goto out_unlock;
+
+ msg = ERR_PTR(-EAGAIN);
+ tmp = msq->q_messages.next;
+ while (tmp != &msq->q_messages) {
+ struct msg_msg *walk_msg;
+ walk_msg = list_entry(tmp,struct msg_msg,m_list);
+ if(testmsg(walk_msg,msgtyp,mode) &&
+ !security_msg_queue_msgrcv(msq, walk_msg, current, msgtyp, mode)) {
+ msg = walk_msg;
+ if(mode == SEARCH_LESSEQUAL && walk_msg->m_type != 1) {
+ msg=walk_msg;
+ msgtyp=walk_msg->m_type-1;
+ } else {
+ msg=walk_msg;
+ break;
+ }
+ }
+ tmp = tmp->next;
+ }
+ if(!IS_ERR(msg)) {
+ /* Found a suitable message. Unlink it from the queue. */
+ if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
+ msg = ERR_PTR(-E2BIG);
+ goto out_unlock;
+ }
+ list_del(&msg->m_list);
+ msq->q_qnum--;
+ msq->q_rtime = get_seconds();
+ msq->q_lrpid = current->tgid;
+ msq->q_cbytes -= msg->m_ts;
+ atomic_sub(msg->m_ts,&msg_bytes);
+ atomic_dec(&msg_hdrs);
+ ss_wakeup(&msq->q_senders,0);
+ msg_unlock(msq);
+ break;
+ }
+ /* No message waiting. Wait for a message */
+ if (msgflg & IPC_NOWAIT) {
+ msg = ERR_PTR(-ENOMSG);
+ goto out_unlock;
+ }
+ list_add_tail(&msr_d.r_list,&msq->q_receivers);
+ msr_d.r_tsk = current;
+ msr_d.r_msgtype = msgtyp;
+ msr_d.r_mode = mode;
+ if(msgflg & MSG_NOERROR)
+ msr_d.r_maxsize = INT_MAX;
+ else
+ msr_d.r_maxsize = msgsz;
+ msr_d.r_msg = ERR_PTR(-EAGAIN);
+ current->state = TASK_INTERRUPTIBLE;
+ msg_unlock(msq);
+
+ schedule();
+
+ /* Lockless receive, part 1:
+ * Disable preemption. We don't hold a reference to the queue
+ * and getting a reference would defeat the idea of a lockless
+ * operation, thus the code relies on rcu to guarantee the
+ * existance of msq:
+ * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
+ * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
+ * rcu_read_lock() prevents preemption between reading r_msg
+ * and the spin_lock() inside ipc_lock_by_ptr().
+ */
+ rcu_read_lock();
+
+ /* Lockless receive, part 2:
+ * Wait until pipelined_send or expunge_all are outside of
+ * wake_up_process(). There is a race with exit(), see
+ * ipc/mqueue.c for the details.
+ */
+ msg = (struct msg_msg*) msr_d.r_msg;
+ while (msg == NULL) {
+ cpu_relax();
+ msg = (struct msg_msg*) msr_d.r_msg;
+ }
+
+ /* Lockless receive, part 3:
+ * If there is a message or an error then accept it without
+ * locking.
+ */
+ if(msg != ERR_PTR(-EAGAIN)) {
+ rcu_read_unlock();
+ break;
+ }
+
+ /* Lockless receive, part 3:
+ * Acquire the queue spinlock.
+ */
+ ipc_lock_by_ptr(&msq->q_perm);
+ rcu_read_unlock();
+
+ /* Lockless receive, part 4:
+ * Repeat test after acquiring the spinlock.
+ */
+ msg = (struct msg_msg*)msr_d.r_msg;
+ if(msg != ERR_PTR(-EAGAIN))
+ goto out_unlock;
+
+ list_del(&msr_d.r_list);
+ if (signal_pending(current)) {
+ msg = ERR_PTR(-ERESTARTNOHAND);
+out_unlock:
+ msg_unlock(msq);
+ break;
+ }
+ }
+ if (IS_ERR(msg))
+ return PTR_ERR(msg);
+
+ msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
+ if (put_user (msg->m_type, &msgp->mtype) ||
+ store_msg(msgp->mtext, msg, msgsz)) {
+ msgsz = -EFAULT;
+ }
+ free_msg(msg);
+ return msgsz;
+}
+
+#ifdef CONFIG_PROC_FS
+static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
+{
+ off_t pos = 0;
+ off_t begin = 0;
+ int i, len = 0;
+
+ down(&msg_ids.sem);
+ len += sprintf(buffer, " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n");
+
+ for(i = 0; i <= msg_ids.max_id; i++) {
+ struct msg_queue * msq;
+ msq = msg_lock(i);
+ if(msq != NULL) {
+ len += sprintf(buffer + len, "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
+ msq->q_perm.key,
+ msg_buildid(i,msq->q_perm.seq),
+ msq->q_perm.mode,
+ msq->q_cbytes,
+ msq->q_qnum,
+ msq->q_lspid,
+ msq->q_lrpid,
+ msq->q_perm.uid,
+ msq->q_perm.gid,
+ msq->q_perm.cuid,
+ msq->q_perm.cgid,
+ msq->q_stime,
+ msq->q_rtime,
+ msq->q_ctime);
+ msg_unlock(msq);
+
+ pos += len;
+ if(pos < offset) {
+ len = 0;
+ begin = pos;
+ }
+ if(pos > offset + length)
+ goto done;
+ }
+
+ }
+ *eof = 1;
+done:
+ up(&msg_ids.sem);
+ *start = buffer + (offset - begin);
+ len -= (offset - begin);
+ if(len > length)
+ len = length;
+ if(len < 0)
+ len = 0;
+ return len;
+}
+#endif