Revision b97021f85517552ea8a0d2c1680c1ee4beab6d14 authored by Benjamin Herrenschmidt on 15 November 2011, 17:11:27 UTC, committed by Benjamin Herrenschmidt on 17 November 2011, 05:26:07 UTC
The Documentation/memory-barriers.txt document requires that atomic operations that return a value act as a memory barrier both before and after the actual atomic operation. Our current implementation doesn't guarantee this. More specifically, while a load following the isync can not be issued before stwcx. has completed, that completion doesn't architecturally means that the result of stwcx. is visible to other processors (or any previous stores for that matter) (typically, the other processors L1 caches can still hold the old value). This has caused an actual crash in RCU torture testing on Power 7 This fixes it by changing those atomic ops to use new macros instead of RELEASE/ACQUIRE barriers, called ATOMIC_ENTRY and ATMOIC_EXIT barriers, which are then defined respectively to lwsync and sync. I haven't had a chance to measure the performance impact (or rather what I measured with kernel compiles is in the noise, I yet have to find a more precise benchmark) Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
1 parent a9a8f77
mqueue.c
/*
* POSIX message queues filesystem for Linux.
*
* Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl)
* Michal Wronski (michal.wronski@gmail.com)
*
* Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com)
* Lockless receive & send, fd based notify:
* Manfred Spraul (manfred@colorfullife.com)
*
* Audit: George Wilson (ltcgcw@us.ibm.com)
*
* This file is released under the GPL.
*/
#include <linux/capability.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/sysctl.h>
#include <linux/poll.h>
#include <linux/mqueue.h>
#include <linux/msg.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/signal.h>
#include <linux/mutex.h>
#include <linux/nsproxy.h>
#include <linux/pid.h>
#include <linux/ipc_namespace.h>
#include <linux/slab.h>
#include <net/sock.h>
#include "util.h"
#define MQUEUE_MAGIC 0x19800202
#define DIRENT_SIZE 20
#define FILENT_SIZE 80
#define SEND 0
#define RECV 1
#define STATE_NONE 0
#define STATE_PENDING 1
#define STATE_READY 2
struct ext_wait_queue { /* queue of sleeping tasks */
struct task_struct *task;
struct list_head list;
struct msg_msg *msg; /* ptr of loaded message */
int state; /* one of STATE_* values */
};
struct mqueue_inode_info {
spinlock_t lock;
struct inode vfs_inode;
wait_queue_head_t wait_q;
struct msg_msg **messages;
struct mq_attr attr;
struct sigevent notify;
struct pid* notify_owner;
struct user_struct *user; /* user who created, for accounting */
struct sock *notify_sock;
struct sk_buff *notify_cookie;
/* for tasks waiting for free space and messages, respectively */
struct ext_wait_queue e_wait_q[2];
unsigned long qsize; /* size of queue in memory (sum of all msgs) */
};
static const struct inode_operations mqueue_dir_inode_operations;
static const struct file_operations mqueue_file_operations;
static const struct super_operations mqueue_super_ops;
static void remove_notification(struct mqueue_inode_info *info);
static struct kmem_cache *mqueue_inode_cachep;
static struct ctl_table_header * mq_sysctl_table;
static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
{
return container_of(inode, struct mqueue_inode_info, vfs_inode);
}
/*
* This routine should be called with the mq_lock held.
*/
static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
{
return get_ipc_ns(inode->i_sb->s_fs_info);
}
static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
{
struct ipc_namespace *ns;
spin_lock(&mq_lock);
ns = __get_ns_from_inode(inode);
spin_unlock(&mq_lock);
return ns;
}
static struct inode *mqueue_get_inode(struct super_block *sb,
struct ipc_namespace *ipc_ns, int mode,
struct mq_attr *attr)
{
struct user_struct *u = current_user();
struct inode *inode;
int ret = -ENOMEM;
inode = new_inode(sb);
if (!inode)
goto err;
inode->i_ino = get_next_ino();
inode->i_mode = mode;
inode->i_uid = current_fsuid();
inode->i_gid = current_fsgid();
inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
if (S_ISREG(mode)) {
struct mqueue_inode_info *info;
struct task_struct *p = current;
unsigned long mq_bytes, mq_msg_tblsz;
inode->i_fop = &mqueue_file_operations;
inode->i_size = FILENT_SIZE;
/* mqueue specific info */
info = MQUEUE_I(inode);
spin_lock_init(&info->lock);
init_waitqueue_head(&info->wait_q);
INIT_LIST_HEAD(&info->e_wait_q[0].list);
INIT_LIST_HEAD(&info->e_wait_q[1].list);
info->notify_owner = NULL;
info->qsize = 0;
info->user = NULL; /* set when all is ok */
memset(&info->attr, 0, sizeof(info->attr));
info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
if (attr) {
info->attr.mq_maxmsg = attr->mq_maxmsg;
info->attr.mq_msgsize = attr->mq_msgsize;
}
mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
if (!info->messages)
goto out_inode;
mq_bytes = (mq_msg_tblsz +
(info->attr.mq_maxmsg * info->attr.mq_msgsize));
spin_lock(&mq_lock);
if (u->mq_bytes + mq_bytes < u->mq_bytes ||
u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
spin_unlock(&mq_lock);
/* mqueue_evict_inode() releases info->messages */
ret = -EMFILE;
goto out_inode;
}
u->mq_bytes += mq_bytes;
spin_unlock(&mq_lock);
/* all is ok */
info->user = get_uid(u);
} else if (S_ISDIR(mode)) {
inc_nlink(inode);
/* Some things misbehave if size == 0 on a directory */
inode->i_size = 2 * DIRENT_SIZE;
inode->i_op = &mqueue_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
}
return inode;
out_inode:
iput(inode);
err:
return ERR_PTR(ret);
}
static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
struct ipc_namespace *ns = data;
int error;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = MQUEUE_MAGIC;
sb->s_op = &mqueue_super_ops;
inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
NULL);
if (IS_ERR(inode)) {
error = PTR_ERR(inode);
goto out;
}
sb->s_root = d_alloc_root(inode);
if (!sb->s_root) {
iput(inode);
error = -ENOMEM;
goto out;
}
error = 0;
out:
return error;
}
static struct dentry *mqueue_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
if (!(flags & MS_KERNMOUNT))
data = current->nsproxy->ipc_ns;
return mount_ns(fs_type, flags, data, mqueue_fill_super);
}
static void init_once(void *foo)
{
struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
inode_init_once(&p->vfs_inode);
}
static struct inode *mqueue_alloc_inode(struct super_block *sb)
{
struct mqueue_inode_info *ei;
ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
if (!ei)
return NULL;
return &ei->vfs_inode;
}
static void mqueue_i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
INIT_LIST_HEAD(&inode->i_dentry);
kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
}
static void mqueue_destroy_inode(struct inode *inode)
{
call_rcu(&inode->i_rcu, mqueue_i_callback);
}
static void mqueue_evict_inode(struct inode *inode)
{
struct mqueue_inode_info *info;
struct user_struct *user;
unsigned long mq_bytes;
int i;
struct ipc_namespace *ipc_ns;
end_writeback(inode);
if (S_ISDIR(inode->i_mode))
return;
ipc_ns = get_ns_from_inode(inode);
info = MQUEUE_I(inode);
spin_lock(&info->lock);
for (i = 0; i < info->attr.mq_curmsgs; i++)
free_msg(info->messages[i]);
kfree(info->messages);
spin_unlock(&info->lock);
/* Total amount of bytes accounted for the mqueue */
mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
+ info->attr.mq_msgsize);
user = info->user;
if (user) {
spin_lock(&mq_lock);
user->mq_bytes -= mq_bytes;
/*
* get_ns_from_inode() ensures that the
* (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
* to which we now hold a reference, or it is NULL.
* We can't put it here under mq_lock, though.
*/
if (ipc_ns)
ipc_ns->mq_queues_count--;
spin_unlock(&mq_lock);
free_uid(user);
}
if (ipc_ns)
put_ipc_ns(ipc_ns);
}
static int mqueue_create(struct inode *dir, struct dentry *dentry,
int mode, struct nameidata *nd)
{
struct inode *inode;
struct mq_attr *attr = dentry->d_fsdata;
int error;
struct ipc_namespace *ipc_ns;
spin_lock(&mq_lock);
ipc_ns = __get_ns_from_inode(dir);
if (!ipc_ns) {
error = -EACCES;
goto out_unlock;
}
if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
!capable(CAP_SYS_RESOURCE)) {
error = -ENOSPC;
goto out_unlock;
}
ipc_ns->mq_queues_count++;
spin_unlock(&mq_lock);
inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
if (IS_ERR(inode)) {
error = PTR_ERR(inode);
spin_lock(&mq_lock);
ipc_ns->mq_queues_count--;
goto out_unlock;
}
put_ipc_ns(ipc_ns);
dir->i_size += DIRENT_SIZE;
dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
d_instantiate(dentry, inode);
dget(dentry);
return 0;
out_unlock:
spin_unlock(&mq_lock);
if (ipc_ns)
put_ipc_ns(ipc_ns);
return error;
}
static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
dir->i_size -= DIRENT_SIZE;
drop_nlink(inode);
dput(dentry);
return 0;
}
/*
* This is routine for system read from queue file.
* To avoid mess with doing here some sort of mq_receive we allow
* to read only queue size & notification info (the only values
* that are interesting from user point of view and aren't accessible
* through std routines)
*/
static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
size_t count, loff_t *off)
{
struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
char buffer[FILENT_SIZE];
ssize_t ret;
spin_lock(&info->lock);
snprintf(buffer, sizeof(buffer),
"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
info->qsize,
info->notify_owner ? info->notify.sigev_notify : 0,
(info->notify_owner &&
info->notify.sigev_notify == SIGEV_SIGNAL) ?
info->notify.sigev_signo : 0,
pid_vnr(info->notify_owner));
spin_unlock(&info->lock);
buffer[sizeof(buffer)-1] = '\0';
ret = simple_read_from_buffer(u_data, count, off, buffer,
strlen(buffer));
if (ret <= 0)
return ret;
filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
return ret;
}
static int mqueue_flush_file(struct file *filp, fl_owner_t id)
{
struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
spin_lock(&info->lock);
if (task_tgid(current) == info->notify_owner)
remove_notification(info);
spin_unlock(&info->lock);
return 0;
}
static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
{
struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
int retval = 0;
poll_wait(filp, &info->wait_q, poll_tab);
spin_lock(&info->lock);
if (info->attr.mq_curmsgs)
retval = POLLIN | POLLRDNORM;
if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
retval |= POLLOUT | POLLWRNORM;
spin_unlock(&info->lock);
return retval;
}
/* Adds current to info->e_wait_q[sr] before element with smaller prio */
static void wq_add(struct mqueue_inode_info *info, int sr,
struct ext_wait_queue *ewp)
{
struct ext_wait_queue *walk;
ewp->task = current;
list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
if (walk->task->static_prio <= current->static_prio) {
list_add_tail(&ewp->list, &walk->list);
return;
}
}
list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
}
/*
* Puts current task to sleep. Caller must hold queue lock. After return
* lock isn't held.
* sr: SEND or RECV
*/
static int wq_sleep(struct mqueue_inode_info *info, int sr,
ktime_t *timeout, struct ext_wait_queue *ewp)
{
int retval;
signed long time;
wq_add(info, sr, ewp);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
spin_unlock(&info->lock);
time = schedule_hrtimeout_range_clock(timeout, 0,
HRTIMER_MODE_ABS, CLOCK_REALTIME);
while (ewp->state == STATE_PENDING)
cpu_relax();
if (ewp->state == STATE_READY) {
retval = 0;
goto out;
}
spin_lock(&info->lock);
if (ewp->state == STATE_READY) {
retval = 0;
goto out_unlock;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
if (time == 0) {
retval = -ETIMEDOUT;
break;
}
}
list_del(&ewp->list);
out_unlock:
spin_unlock(&info->lock);
out:
return retval;
}
/*
* Returns waiting task that should be serviced first or NULL if none exists
*/
static struct ext_wait_queue *wq_get_first_waiter(
struct mqueue_inode_info *info, int sr)
{
struct list_head *ptr;
ptr = info->e_wait_q[sr].list.prev;
if (ptr == &info->e_wait_q[sr].list)
return NULL;
return list_entry(ptr, struct ext_wait_queue, list);
}
/* Auxiliary functions to manipulate messages' list */
static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
{
int k;
k = info->attr.mq_curmsgs - 1;
while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
info->messages[k + 1] = info->messages[k];
k--;
}
info->attr.mq_curmsgs++;
info->qsize += ptr->m_ts;
info->messages[k + 1] = ptr;
}
static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
{
info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
return info->messages[info->attr.mq_curmsgs];
}
static inline void set_cookie(struct sk_buff *skb, char code)
{
((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
}
/*
* The next function is only to split too long sys_mq_timedsend
*/
static void __do_notify(struct mqueue_inode_info *info)
{
/* notification
* invoked when there is registered process and there isn't process
* waiting synchronously for message AND state of queue changed from
* empty to not empty. Here we are sure that no one is waiting
* synchronously. */
if (info->notify_owner &&
info->attr.mq_curmsgs == 1) {
struct siginfo sig_i;
switch (info->notify.sigev_notify) {
case SIGEV_NONE:
break;
case SIGEV_SIGNAL:
/* sends signal */
sig_i.si_signo = info->notify.sigev_signo;
sig_i.si_errno = 0;
sig_i.si_code = SI_MESGQ;
sig_i.si_value = info->notify.sigev_value;
sig_i.si_pid = task_tgid_nr_ns(current,
ns_of_pid(info->notify_owner));
sig_i.si_uid = current_uid();
kill_pid_info(info->notify.sigev_signo,
&sig_i, info->notify_owner);
break;
case SIGEV_THREAD:
set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
netlink_sendskb(info->notify_sock, info->notify_cookie);
break;
}
/* after notification unregisters process */
put_pid(info->notify_owner);
info->notify_owner = NULL;
}
wake_up(&info->wait_q);
}
static int prepare_timeout(const struct timespec __user *u_abs_timeout,
ktime_t *expires, struct timespec *ts)
{
if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
return -EFAULT;
if (!timespec_valid(ts))
return -EINVAL;
*expires = timespec_to_ktime(*ts);
return 0;
}
static void remove_notification(struct mqueue_inode_info *info)
{
if (info->notify_owner != NULL &&
info->notify.sigev_notify == SIGEV_THREAD) {
set_cookie(info->notify_cookie, NOTIFY_REMOVED);
netlink_sendskb(info->notify_sock, info->notify_cookie);
}
put_pid(info->notify_owner);
info->notify_owner = NULL;
}
static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
{
if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
return 0;
if (capable(CAP_SYS_RESOURCE)) {
if (attr->mq_maxmsg > HARD_MSGMAX)
return 0;
} else {
if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
attr->mq_msgsize > ipc_ns->mq_msgsize_max)
return 0;
}
/* check for overflow */
if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
return 0;
if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
+ sizeof (struct msg_msg *))) <
(unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
return 0;
return 1;
}
/*
* Invoked when creating a new queue via sys_mq_open
*/
static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
struct dentry *dentry, int oflag, mode_t mode,
struct mq_attr *attr)
{
const struct cred *cred = current_cred();
struct file *result;
int ret;
if (attr) {
if (!mq_attr_ok(ipc_ns, attr)) {
ret = -EINVAL;
goto out;
}
/* store for use during create */
dentry->d_fsdata = attr;
}
mode &= ~current_umask();
ret = mnt_want_write(ipc_ns->mq_mnt);
if (ret)
goto out;
ret = vfs_create(dir->d_inode, dentry, mode, NULL);
dentry->d_fsdata = NULL;
if (ret)
goto out_drop_write;
result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
/*
* dentry_open() took a persistent mnt_want_write(),
* so we can now drop this one.
*/
mnt_drop_write(ipc_ns->mq_mnt);
return result;
out_drop_write:
mnt_drop_write(ipc_ns->mq_mnt);
out:
dput(dentry);
mntput(ipc_ns->mq_mnt);
return ERR_PTR(ret);
}
/* Opens existing queue */
static struct file *do_open(struct ipc_namespace *ipc_ns,
struct dentry *dentry, int oflag)
{
int ret;
const struct cred *cred = current_cred();
static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
MAY_READ | MAY_WRITE };
if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
ret = -EINVAL;
goto err;
}
if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
ret = -EACCES;
goto err;
}
return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
err:
dput(dentry);
mntput(ipc_ns->mq_mnt);
return ERR_PTR(ret);
}
SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
struct mq_attr __user *, u_attr)
{
struct dentry *dentry;
struct file *filp;
char *name;
struct mq_attr attr;
int fd, error;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
return -EFAULT;
audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
if (IS_ERR(name = getname(u_name)))
return PTR_ERR(name);
fd = get_unused_fd_flags(O_CLOEXEC);
if (fd < 0)
goto out_putname;
mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
if (IS_ERR(dentry)) {
error = PTR_ERR(dentry);
goto out_putfd;
}
mntget(ipc_ns->mq_mnt);
if (oflag & O_CREAT) {
if (dentry->d_inode) { /* entry already exists */
audit_inode(name, dentry);
if (oflag & O_EXCL) {
error = -EEXIST;
goto out;
}
filp = do_open(ipc_ns, dentry, oflag);
} else {
filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
dentry, oflag, mode,
u_attr ? &attr : NULL);
}
} else {
if (!dentry->d_inode) {
error = -ENOENT;
goto out;
}
audit_inode(name, dentry);
filp = do_open(ipc_ns, dentry, oflag);
}
if (IS_ERR(filp)) {
error = PTR_ERR(filp);
goto out_putfd;
}
fd_install(fd, filp);
goto out_upsem;
out:
dput(dentry);
mntput(ipc_ns->mq_mnt);
out_putfd:
put_unused_fd(fd);
fd = error;
out_upsem:
mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
out_putname:
putname(name);
return fd;
}
SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
{
int err;
char *name;
struct dentry *dentry;
struct inode *inode = NULL;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
name = getname(u_name);
if (IS_ERR(name))
return PTR_ERR(name);
mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
I_MUTEX_PARENT);
dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
goto out_unlock;
}
if (!dentry->d_inode) {
err = -ENOENT;
goto out_err;
}
inode = dentry->d_inode;
if (inode)
ihold(inode);
err = mnt_want_write(ipc_ns->mq_mnt);
if (err)
goto out_err;
err = vfs_unlink(dentry->d_parent->d_inode, dentry);
mnt_drop_write(ipc_ns->mq_mnt);
out_err:
dput(dentry);
out_unlock:
mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
putname(name);
if (inode)
iput(inode);
return err;
}
/* Pipelined send and receive functions.
*
* If a receiver finds no waiting message, then it registers itself in the
* list of waiting receivers. A sender checks that list before adding the new
* message into the message array. If there is a waiting receiver, then it
* bypasses the message array and directly hands the message over to the
* receiver.
* The receiver accepts the message and returns without grabbing the queue
* spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
* are necessary. The same algorithm is used for sysv semaphores, see
* ipc/sem.c for more details.
*
* The same algorithm is used for senders.
*/
/* pipelined_send() - send a message directly to the task waiting in
* sys_mq_timedreceive() (without inserting message into a queue).
*/
static inline void pipelined_send(struct mqueue_inode_info *info,
struct msg_msg *message,
struct ext_wait_queue *receiver)
{
receiver->msg = message;
list_del(&receiver->list);
receiver->state = STATE_PENDING;
wake_up_process(receiver->task);
smp_wmb();
receiver->state = STATE_READY;
}
/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
* gets its message and put to the queue (we have one free place for sure). */
static inline void pipelined_receive(struct mqueue_inode_info *info)
{
struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
if (!sender) {
/* for poll */
wake_up_interruptible(&info->wait_q);
return;
}
msg_insert(sender->msg, info);
list_del(&sender->list);
sender->state = STATE_PENDING;
wake_up_process(sender->task);
smp_wmb();
sender->state = STATE_READY;
}
SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
size_t, msg_len, unsigned int, msg_prio,
const struct timespec __user *, u_abs_timeout)
{
struct file *filp;
struct inode *inode;
struct ext_wait_queue wait;
struct ext_wait_queue *receiver;
struct msg_msg *msg_ptr;
struct mqueue_inode_info *info;
ktime_t expires, *timeout = NULL;
struct timespec ts;
int ret;
if (u_abs_timeout) {
int res = prepare_timeout(u_abs_timeout, &expires, &ts);
if (res)
return res;
timeout = &expires;
}
if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
return -EINVAL;
audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
filp = fget(mqdes);
if (unlikely(!filp)) {
ret = -EBADF;
goto out;
}
inode = filp->f_path.dentry->d_inode;
if (unlikely(filp->f_op != &mqueue_file_operations)) {
ret = -EBADF;
goto out_fput;
}
info = MQUEUE_I(inode);
audit_inode(NULL, filp->f_path.dentry);
if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
ret = -EBADF;
goto out_fput;
}
if (unlikely(msg_len > info->attr.mq_msgsize)) {
ret = -EMSGSIZE;
goto out_fput;
}
/* First try to allocate memory, before doing anything with
* existing queues. */
msg_ptr = load_msg(u_msg_ptr, msg_len);
if (IS_ERR(msg_ptr)) {
ret = PTR_ERR(msg_ptr);
goto out_fput;
}
msg_ptr->m_ts = msg_len;
msg_ptr->m_type = msg_prio;
spin_lock(&info->lock);
if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
if (filp->f_flags & O_NONBLOCK) {
spin_unlock(&info->lock);
ret = -EAGAIN;
} else {
wait.task = current;
wait.msg = (void *) msg_ptr;
wait.state = STATE_NONE;
ret = wq_sleep(info, SEND, timeout, &wait);
}
if (ret < 0)
free_msg(msg_ptr);
} else {
receiver = wq_get_first_waiter(info, RECV);
if (receiver) {
pipelined_send(info, msg_ptr, receiver);
} else {
/* adds message to the queue */
msg_insert(msg_ptr, info);
__do_notify(info);
}
inode->i_atime = inode->i_mtime = inode->i_ctime =
CURRENT_TIME;
spin_unlock(&info->lock);
ret = 0;
}
out_fput:
fput(filp);
out:
return ret;
}
SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
size_t, msg_len, unsigned int __user *, u_msg_prio,
const struct timespec __user *, u_abs_timeout)
{
ssize_t ret;
struct msg_msg *msg_ptr;
struct file *filp;
struct inode *inode;
struct mqueue_inode_info *info;
struct ext_wait_queue wait;
ktime_t expires, *timeout = NULL;
struct timespec ts;
if (u_abs_timeout) {
int res = prepare_timeout(u_abs_timeout, &expires, &ts);
if (res)
return res;
timeout = &expires;
}
audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
filp = fget(mqdes);
if (unlikely(!filp)) {
ret = -EBADF;
goto out;
}
inode = filp->f_path.dentry->d_inode;
if (unlikely(filp->f_op != &mqueue_file_operations)) {
ret = -EBADF;
goto out_fput;
}
info = MQUEUE_I(inode);
audit_inode(NULL, filp->f_path.dentry);
if (unlikely(!(filp->f_mode & FMODE_READ))) {
ret = -EBADF;
goto out_fput;
}
/* checks if buffer is big enough */
if (unlikely(msg_len < info->attr.mq_msgsize)) {
ret = -EMSGSIZE;
goto out_fput;
}
spin_lock(&info->lock);
if (info->attr.mq_curmsgs == 0) {
if (filp->f_flags & O_NONBLOCK) {
spin_unlock(&info->lock);
ret = -EAGAIN;
} else {
wait.task = current;
wait.state = STATE_NONE;
ret = wq_sleep(info, RECV, timeout, &wait);
msg_ptr = wait.msg;
}
} else {
msg_ptr = msg_get(info);
inode->i_atime = inode->i_mtime = inode->i_ctime =
CURRENT_TIME;
/* There is now free space in queue. */
pipelined_receive(info);
spin_unlock(&info->lock);
ret = 0;
}
if (ret == 0) {
ret = msg_ptr->m_ts;
if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
ret = -EFAULT;
}
free_msg(msg_ptr);
}
out_fput:
fput(filp);
out:
return ret;
}
/*
* Notes: the case when user wants us to deregister (with NULL as pointer)
* and he isn't currently owner of notification, will be silently discarded.
* It isn't explicitly defined in the POSIX.
*/
SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
const struct sigevent __user *, u_notification)
{
int ret;
struct file *filp;
struct sock *sock;
struct inode *inode;
struct sigevent notification;
struct mqueue_inode_info *info;
struct sk_buff *nc;
if (u_notification) {
if (copy_from_user(¬ification, u_notification,
sizeof(struct sigevent)))
return -EFAULT;
}
audit_mq_notify(mqdes, u_notification ? ¬ification : NULL);
nc = NULL;
sock = NULL;
if (u_notification != NULL) {
if (unlikely(notification.sigev_notify != SIGEV_NONE &&
notification.sigev_notify != SIGEV_SIGNAL &&
notification.sigev_notify != SIGEV_THREAD))
return -EINVAL;
if (notification.sigev_notify == SIGEV_SIGNAL &&
!valid_signal(notification.sigev_signo)) {
return -EINVAL;
}
if (notification.sigev_notify == SIGEV_THREAD) {
long timeo;
/* create the notify skb */
nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
if (!nc) {
ret = -ENOMEM;
goto out;
}
if (copy_from_user(nc->data,
notification.sigev_value.sival_ptr,
NOTIFY_COOKIE_LEN)) {
ret = -EFAULT;
goto out;
}
/* TODO: add a header? */
skb_put(nc, NOTIFY_COOKIE_LEN);
/* and attach it to the socket */
retry:
filp = fget(notification.sigev_signo);
if (!filp) {
ret = -EBADF;
goto out;
}
sock = netlink_getsockbyfilp(filp);
fput(filp);
if (IS_ERR(sock)) {
ret = PTR_ERR(sock);
sock = NULL;
goto out;
}
timeo = MAX_SCHEDULE_TIMEOUT;
ret = netlink_attachskb(sock, nc, &timeo, NULL);
if (ret == 1)
goto retry;
if (ret) {
sock = NULL;
nc = NULL;
goto out;
}
}
}
filp = fget(mqdes);
if (!filp) {
ret = -EBADF;
goto out;
}
inode = filp->f_path.dentry->d_inode;
if (unlikely(filp->f_op != &mqueue_file_operations)) {
ret = -EBADF;
goto out_fput;
}
info = MQUEUE_I(inode);
ret = 0;
spin_lock(&info->lock);
if (u_notification == NULL) {
if (info->notify_owner == task_tgid(current)) {
remove_notification(info);
inode->i_atime = inode->i_ctime = CURRENT_TIME;
}
} else if (info->notify_owner != NULL) {
ret = -EBUSY;
} else {
switch (notification.sigev_notify) {
case SIGEV_NONE:
info->notify.sigev_notify = SIGEV_NONE;
break;
case SIGEV_THREAD:
info->notify_sock = sock;
info->notify_cookie = nc;
sock = NULL;
nc = NULL;
info->notify.sigev_notify = SIGEV_THREAD;
break;
case SIGEV_SIGNAL:
info->notify.sigev_signo = notification.sigev_signo;
info->notify.sigev_value = notification.sigev_value;
info->notify.sigev_notify = SIGEV_SIGNAL;
break;
}
info->notify_owner = get_pid(task_tgid(current));
inode->i_atime = inode->i_ctime = CURRENT_TIME;
}
spin_unlock(&info->lock);
out_fput:
fput(filp);
out:
if (sock) {
netlink_detachskb(sock, nc);
} else if (nc) {
dev_kfree_skb(nc);
}
return ret;
}
SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
const struct mq_attr __user *, u_mqstat,
struct mq_attr __user *, u_omqstat)
{
int ret;
struct mq_attr mqstat, omqstat;
struct file *filp;
struct inode *inode;
struct mqueue_inode_info *info;
if (u_mqstat != NULL) {
if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
return -EFAULT;
if (mqstat.mq_flags & (~O_NONBLOCK))
return -EINVAL;
}
filp = fget(mqdes);
if (!filp) {
ret = -EBADF;
goto out;
}
inode = filp->f_path.dentry->d_inode;
if (unlikely(filp->f_op != &mqueue_file_operations)) {
ret = -EBADF;
goto out_fput;
}
info = MQUEUE_I(inode);
spin_lock(&info->lock);
omqstat = info->attr;
omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
if (u_mqstat) {
audit_mq_getsetattr(mqdes, &mqstat);
spin_lock(&filp->f_lock);
if (mqstat.mq_flags & O_NONBLOCK)
filp->f_flags |= O_NONBLOCK;
else
filp->f_flags &= ~O_NONBLOCK;
spin_unlock(&filp->f_lock);
inode->i_atime = inode->i_ctime = CURRENT_TIME;
}
spin_unlock(&info->lock);
ret = 0;
if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
sizeof(struct mq_attr)))
ret = -EFAULT;
out_fput:
fput(filp);
out:
return ret;
}
static const struct inode_operations mqueue_dir_inode_operations = {
.lookup = simple_lookup,
.create = mqueue_create,
.unlink = mqueue_unlink,
};
static const struct file_operations mqueue_file_operations = {
.flush = mqueue_flush_file,
.poll = mqueue_poll_file,
.read = mqueue_read_file,
.llseek = default_llseek,
};
static const struct super_operations mqueue_super_ops = {
.alloc_inode = mqueue_alloc_inode,
.destroy_inode = mqueue_destroy_inode,
.evict_inode = mqueue_evict_inode,
.statfs = simple_statfs,
};
static struct file_system_type mqueue_fs_type = {
.name = "mqueue",
.mount = mqueue_mount,
.kill_sb = kill_litter_super,
};
int mq_init_ns(struct ipc_namespace *ns)
{
ns->mq_queues_count = 0;
ns->mq_queues_max = DFLT_QUEUESMAX;
ns->mq_msg_max = DFLT_MSGMAX;
ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
if (IS_ERR(ns->mq_mnt)) {
int err = PTR_ERR(ns->mq_mnt);
ns->mq_mnt = NULL;
return err;
}
return 0;
}
void mq_clear_sbinfo(struct ipc_namespace *ns)
{
ns->mq_mnt->mnt_sb->s_fs_info = NULL;
}
void mq_put_mnt(struct ipc_namespace *ns)
{
mntput(ns->mq_mnt);
}
static int __init init_mqueue_fs(void)
{
int error;
mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
sizeof(struct mqueue_inode_info), 0,
SLAB_HWCACHE_ALIGN, init_once);
if (mqueue_inode_cachep == NULL)
return -ENOMEM;
/* ignore failures - they are not fatal */
mq_sysctl_table = mq_register_sysctl_table();
error = register_filesystem(&mqueue_fs_type);
if (error)
goto out_sysctl;
spin_lock_init(&mq_lock);
init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
if (IS_ERR(init_ipc_ns.mq_mnt)) {
error = PTR_ERR(init_ipc_ns.mq_mnt);
goto out_filesystem;
}
return 0;
out_filesystem:
unregister_filesystem(&mqueue_fs_type);
out_sysctl:
if (mq_sysctl_table)
unregister_sysctl_table(mq_sysctl_table);
kmem_cache_destroy(mqueue_inode_cachep);
return error;
}
__initcall(init_mqueue_fs);
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