* [PATCH v4 1/4] IPC: Added two new system call mq_recvmmsg() and mq_sendmmsg()
2026-09-24 15:34 [PATCH v4 0/4] Add two new system call mq_recvmmsg() and mq_sendmmsg() to posix ipc mqueue mathura kumar
@ 2026-09-24 15:34 ` mathura kumar
2026-09-24 15:35 ` [PATCH v4 2/4] IPC: Added system call entry in all of most common architectures mathura kumar
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: mathura kumar @ 2026-09-24 15:34 UTC (permalink / raw)
To: brauner; +Cc: linux-kernel, linux-arch, corbet, mathura.kumar.tech
Implement two new POSIX message queue system calls,
mq_sendmmsg() and mq_recvmmsg(), analogous to the
existing sendmmsg()/recvmmsg() socket system calls.
These allow sending and receiving or peek multiple messages in a
single syscall,reducing the overhead of repeated context switches
per discrete message.
It contains the core implementation of both system calls as
part of a larger patchset.
long mq_sendmmsg(mqd_t mqdes, struct mq_mmsg_attrs *attrs,
unsigned int attrs_len, unsigned long start_idx,
const struct __kernel_timespec *u_abs_timeout);
long mq_recvmmsg(mqd_t mqdes, struct mq_mmsg_attrs *attrs,
unsigned int attrs_len, unsigned int flags,
unsigned long start_idx,
const struct __kernel_timespec *u_abs_timeout);
Implementation complete details available under
mq_recvmmsg.rst and mq_sendmmsg.rst
Signed-off-by: mathura kumar <mathura.kumar.tech@gmail.com>
---
include/linux/compat.h | 12 +-
include/linux/syscalls.h | 9 +
include/uapi/asm-generic/unistd.h | 9 +-
include/uapi/linux/mqueue.h | 27 +-
ipc/mqueue.c | 595 ++++++++++++++++++++++++++++--
ipc/msg.c | 2 +-
ipc/msgutil.c | 45 ++-
ipc/util.h | 3 +-
kernel/sys_ni.c | 6 +
9 files changed, 645 insertions(+), 63 deletions(-)
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 8da0a15c95f4..cb6cda4aebdd 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -18,7 +18,6 @@
#include <linux/aio_abi.h> /* for aio_context_t */
#include <linux/uaccess.h>
#include <linux/unistd.h>
-
#include <asm/compat.h>
#include <asm/siginfo.h>
#include <asm/signal.h>
@@ -428,6 +427,8 @@ struct compat_sysctl_args;
struct compat_kexec_segment;
struct compat_mq_attr;
struct compat_msgbuf;
+struct compat_msg_attrs;
+struct compat_mq_mmsg_attrs;
void copy_siginfo_to_external32(struct compat_siginfo *to,
const struct kernel_siginfo *from);
@@ -805,8 +806,13 @@ asmlinkage long compat_sys_pwritev64v2(unsigned long fd,
const struct iovec __user *vec,
unsigned long vlen, loff_t pos, rwf_t flags);
#endif
-
-
+asmlinkage long compat_sys_mq_sendmmsg(mqd_t mqdes, struct compat_mq_mmsg_attrs __user *attrs,
+ unsigned int attrs_len, unsigned long start_index,
+ const struct __kernel_timespec __user *abs_timeout);
+asmlinkage long compat_sys_mq_recvmmsg(mqd_t mqdes, struct compat_mq_mmsg_attrs __user *attrs,
+ unsigned int attrs_len, unsigned int flags,
+ unsigned long start_index,
+ const struct __kernel_timespec __user *abs_timeout);
/*
* Deprecated system calls which are still defined in
* include/uapi/asm-generic/unistd.h and wanted by >= 1 arch
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 874d9067a43b..0abf938e86da 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -79,6 +79,8 @@ struct mnt_id_req;
struct ns_id_req;
struct xattr_args;
struct file_attr;
+struct mq_msg_attrs;
+struct mq_mmsg_attrs;
#include <linux/types.h>
#include <linux/aio_abi.h>
@@ -739,7 +741,14 @@ asmlinkage long sys_sysinfo(struct sysinfo __user *info);
asmlinkage long sys_mq_open(const char __user *name, int oflag, umode_t mode, struct mq_attr __user *attr);
asmlinkage long sys_mq_unlink(const char __user *name);
asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *msg_ptr, size_t msg_len, unsigned int msg_prio, const struct __kernel_timespec __user *abs_timeout);
+asmlinkage long sys_mq_sendmmsg(mqd_t mqdes, struct mq_mmsg_attrs __user *attrs,
+ unsigned int attrs_len, unsigned long start_index,
+ const struct __kernel_timespec __user *abs_timeout);
asmlinkage long sys_mq_timedreceive(mqd_t mqdes, char __user *msg_ptr, size_t msg_len, unsigned int __user *msg_prio, const struct __kernel_timespec __user *abs_timeout);
+asmlinkage long sys_mq_recvmmsg(mqd_t mqdes, struct mq_mmsg_attrs __user *attrs,
+ unsigned int attrs_len, unsigned int flags,
+ unsigned long start_index,
+ const struct __kernel_timespec __user *abs_timeout);
asmlinkage long sys_mq_notify(mqd_t mqdes, const struct sigevent __user *notification);
asmlinkage long sys_mq_getsetattr(mqd_t mqdes, const struct mq_attr __user *mqstat, struct mq_attr __user *omqstat);
asmlinkage long sys_mq_timedreceive_time32(mqd_t mqdes,
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index a627acc8fb5f..1d06486d3aa5 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -863,9 +863,14 @@ __SYSCALL(__NR_listns, sys_listns)
#define __NR_rseq_slice_yield 471
__SYSCALL(__NR_rseq_slice_yield, sys_rseq_slice_yield)
-#undef __NR_syscalls
-#define __NR_syscalls 472
+#define __NR_mq_recvmmsg 472
+__SC_COMP(__NR_mq_recvmmsg, sys_mq_recvmmsg, compat_sys_mq_recvmmsg)
+
+#define __NR_mq_sendmmsg 473
+__SC_COMP(__NR_mq_sendmmsg, sys_mq_sendmmsg, compat_sys_mq_sendmmsg)
+#undef __NR_syscalls
+#define __NR_syscalls 474
/*
* 32 bit systems traditionally used different
* syscalls for off_t and loff_t arguments, while
diff --git a/include/uapi/linux/mqueue.h b/include/uapi/linux/mqueue.h
index b516b66840ad..6ce21e41eb18 100644
--- a/include/uapi/linux/mqueue.h
+++ b/include/uapi/linux/mqueue.h
@@ -18,8 +18,9 @@
#ifndef _LINUX_MQUEUE_H
#define _LINUX_MQUEUE_H
-
+#include <linux/uio.h>
#include <linux/types.h>
+#include <linux/compat.h>
#define MQ_PRIO_MAX 32768
/* per-uid limit of kernel memory used by mqueue, in bytes */
@@ -33,6 +34,30 @@ struct mq_attr {
__kernel_long_t __reserved[4]; /* ignored for input, zeroed for output */
};
+struct mq_msg_attrs {
+ __kernel_size_t msg_len;
+ unsigned int __user *msg_prio;
+ void __user *msg_ptr;
+};
+
+struct mq_mmsg_attrs {
+ struct iovec __user *msg_attrs_vec;
+ __kernel_size_t vlen;
+ int __user *ret;
+};
+
+struct compat_msg_attrs {
+ compat_size_t msg_len;
+ compat_uptr_t __user msg_prio;
+ compat_uptr_t __user msg_ptr;
+};
+
+struct compat_mq_mmsg_attrs {
+ compat_uptr_t __user msg_attrs_vec;
+ compat_size_t vlen;
+ compat_uptr_t __user ret;
+};
+
/*
* SIGEV_THREAD implementation:
* SIGEV_THREAD must be implemented in user space. If SIGEV_THREAD is passed
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 4798b375972b..a19e24f7b3aa 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -11,7 +11,8 @@
*
* Audit: George Wilson (ltcgcw@us.ibm.com)
*/
-
+#include "linux/build_bug.h"
+#include "linux/printk.h"
#include <linux/capability.h>
#include <linux/init.h>
#include <linux/pagemap.h>
@@ -39,7 +40,10 @@
#include <linux/sched/signal.h>
#include <linux/sched/user.h>
+#include <linux/uio.h>
+#include <linux/uaccess.h>
#include <net/sock.h>
+#include <linux/rbtree_augmented.h>
#include "util.h"
struct mqueue_fs_context {
@@ -54,6 +58,16 @@ struct mqueue_fs_context {
#define SEND 0
#define RECV 1
+#define MQ_PEEK 0x02
+#define MQ_RECV 0x04
+#define MQ_VALID_FLAGS (MQ_PEEK | MQ_RECV)
+
+/* List of all mq_mmsg_attrs "versions". */
+#define MQ_MMSG_ATTRS_SIZE_VER0 24
+#define MQ_MMSG_ATTRS_SIZE_LATEST MQ_MMSG_ATTRS_SIZE_VER0
+#define COMPAT_MQ_MMSG_ATTRS_SIZE_VER0 12
+#define COMPAT_MQ_MMSG_ATTRS_SIZE_LATEST COMPAT_MQ_MMSG_ATTRS_SIZE_VER0
+
#define STATE_NONE 0
#define STATE_READY 1
@@ -61,6 +75,8 @@ struct posix_msg_tree_node {
struct rb_node rb_node;
struct list_head msg_list;
int priority;
+ unsigned int msg_count; /* Total messages at exactly this priority */
+ unsigned int subtree_msg_count; /* sum of messages in this node and all descendants */
};
/*
@@ -186,7 +202,53 @@ static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
return ns;
}
-/* Auxiliary functions to manipulate messages' list */
+static inline unsigned int get_subtree_count(struct rb_node *node)
+{
+ if (!node)
+ return 0;
+ return rb_entry(node, struct posix_msg_tree_node, rb_node)->subtree_msg_count;
+}
+
+static void msg_tree_propagate_subtree_msg_count(struct rb_node *node, struct rb_node *stop)
+{
+ while (node != stop) {
+ struct posix_msg_tree_node *leaf = rb_entry(node, struct posix_msg_tree_node,
+ rb_node);
+ unsigned int new_count = leaf->msg_count +
+ get_subtree_count(node->rb_left) +
+ get_subtree_count(node->rb_right);
+ if (leaf->subtree_msg_count == new_count)
+ break;
+ leaf->subtree_msg_count = new_count;
+ node = rb_parent(node);
+ }
+}
+
+static void msg_tree_copy_subtree_msg_count(struct rb_node *old, struct rb_node *new)
+{
+ struct posix_msg_tree_node *old_leaf = rb_entry(old, struct posix_msg_tree_node, rb_node);
+ struct posix_msg_tree_node *new_leaf = rb_entry(new, struct posix_msg_tree_node, rb_node);
+
+ new_leaf->subtree_msg_count = old_leaf->subtree_msg_count;
+}
+
+static void msg_tree_rotate_subtree_msg_count(struct rb_node *old, struct rb_node *new)
+{
+ struct posix_msg_tree_node *old_leaf = rb_entry(old, struct posix_msg_tree_node, rb_node);
+ struct posix_msg_tree_node *new_leaf = rb_entry(new, struct posix_msg_tree_node, rb_node);
+
+ new_leaf->subtree_msg_count = old_leaf->subtree_msg_count;
+ old_leaf->subtree_msg_count = old_leaf->msg_count +
+ get_subtree_count(old->rb_left) +
+ get_subtree_count(old->rb_right);
+}
+
+static const struct rb_augment_callbacks msg_tree_callbacks = {
+ .propagate = msg_tree_propagate_subtree_msg_count,
+ .copy = msg_tree_copy_subtree_msg_count,
+ .rotate = msg_tree_rotate_subtree_msg_count
+};
+
static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
{
struct rb_node **p, *parent = NULL;
@@ -216,13 +278,20 @@ static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
INIT_LIST_HEAD(&leaf->msg_list);
}
leaf->priority = msg->m_type;
+ leaf->msg_count = 1;
+ leaf->subtree_msg_count = 1;
if (rightmost)
info->msg_tree_rightmost = &leaf->rb_node;
rb_link_node(&leaf->rb_node, parent, p);
- rb_insert_color(&leaf->rb_node, &info->msg_tree);
+ msg_tree_propagate_subtree_msg_count(parent, NULL);
+ rb_insert_augmented(&leaf->rb_node, &info->msg_tree, &msg_tree_callbacks);
+ goto common_insert;
insert_msg:
+ leaf->msg_count++;
+ msg_tree_propagate_subtree_msg_count(&leaf->rb_node, NULL);
+common_insert:
info->attr.mq_curmsgs++;
info->qsize += msg->m_ts;
list_add_tail(&msg->m_list, &leaf->msg_list);
@@ -236,8 +305,7 @@ static inline void msg_tree_erase(struct posix_msg_tree_node *leaf,
if (info->msg_tree_rightmost == node)
info->msg_tree_rightmost = rb_prev(node);
-
- rb_erase(node, &info->msg_tree);
+ rb_erase_augmented(node, &info->msg_tree, &msg_tree_callbacks);
if (info->node_cache)
kfree(leaf);
else
@@ -277,8 +345,11 @@ static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
msg = list_first_entry(&leaf->msg_list,
struct msg_msg, m_list);
list_del(&msg->m_list);
+ leaf->msg_count--;
if (list_empty(&leaf->msg_list)) {
msg_tree_erase(leaf, info);
+ } else {
+ msg_tree_propagate_subtree_msg_count(&leaf->rb_node, NULL);
}
}
info->attr.mq_curmsgs--;
@@ -765,7 +836,6 @@ static struct ext_wait_queue *wq_get_first_waiter(
return list_entry(ptr, struct ext_wait_queue, list);
}
-
static inline void set_cookie(struct sk_buff *skb, char code)
{
((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
@@ -1034,29 +1104,27 @@ static inline void pipelined_receive(struct wake_q_head *wake_q,
__pipelined_op(wake_q, info, sender);
}
-static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
- size_t msg_len, unsigned int msg_prio,
- struct timespec64 *ts)
+static ssize_t do_mq_sendmsg(mqd_t mqdes, const char __user *u_msg_ptr, size_t msg_len,
+ unsigned int msg_prio, ktime_t *timeout)
{
+ ssize_t ret = 0;
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 posix_msg_tree_node *new_leaf = NULL;
- int ret = 0;
- DEFINE_WAKE_Q(wake_q);
+ struct timespec64 ts, *abs_timeout = NULL;
+ DEFINE_WAKE_Q(wake_q);
if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
return -EINVAL;
- if (ts) {
- expires = timespec64_to_ktime(*ts);
- timeout = &expires;
+ if (timeout) {
+ ts = ktime_to_timespec64(*timeout);
+ abs_timeout = &ts;
}
-
- audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts);
+ audit_mq_sendrecv(mqdes, msg_len, msg_prio, abs_timeout);
CLASS(fd, f)(mqdes);
if (fd_empty(f))
@@ -1139,24 +1207,37 @@ static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
return ret;
}
-static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
- size_t msg_len, unsigned int __user *u_msg_prio,
- struct timespec64 *ts)
+static ssize_t do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
+ size_t msg_len, unsigned int msg_prio,
+ struct timespec64 *ts)
+{
+ ktime_t expires, *timeout = NULL;
+
+ if (ts) {
+ expires = timespec64_to_ktime(*ts);
+ timeout = &expires;
+ }
+
+ return do_mq_sendmsg(mqdes, u_msg_ptr, msg_len, msg_prio, timeout);
+}
+
+static ssize_t do_mq_recvmsg(mqd_t mqdes, char __user *u_msg_ptr, size_t msg_len,
+ unsigned int __user *u_msg_prio, ktime_t *timeout)
{
ssize_t ret;
struct msg_msg *msg_ptr;
struct inode *inode;
struct mqueue_inode_info *info;
struct ext_wait_queue wait;
- ktime_t expires, *timeout = NULL;
struct posix_msg_tree_node *new_leaf = NULL;
+ struct timespec64 ts, *abs_timeout = NULL;
- if (ts) {
- expires = timespec64_to_ktime(*ts);
- timeout = &expires;
+ if (timeout) {
+ ts = ktime_to_timespec64(*timeout);
+ abs_timeout = &ts;
}
- audit_mq_sendrecv(mqdes, msg_len, 0, ts);
+ audit_mq_sendrecv(mqdes, msg_len, 0, abs_timeout);
CLASS(fd, f)(mqdes);
if (fd_empty(f))
@@ -1222,7 +1303,7 @@ static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
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)) {
+ store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
ret = -EFAULT;
}
free_msg(msg_ptr);
@@ -1230,6 +1311,366 @@ static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
return ret;
}
+static ssize_t do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, size_t msg_len,
+ unsigned int __user *u_msg_prio, struct timespec64 *ts)
+{
+ ktime_t expires, *timeout = NULL;
+
+ if (ts) {
+ expires = timespec64_to_ktime(*ts);
+ timeout = &expires;
+ }
+
+ return do_mq_recvmsg(mqdes, u_msg_ptr, msg_len, u_msg_prio, timeout);
+}
+
+static struct msg_msg *mq_peek_index(struct mqueue_inode_info *info, unsigned long index)
+{
+ struct rb_node *node;
+ struct posix_msg_tree_node *leaf;
+ struct msg_msg *msg;
+ unsigned int right_count;
+ unsigned int offset;
+ unsigned int i = 0;
+
+ node = info->msg_tree.rb_node;
+ while (node) {
+ leaf = rb_entry(node, struct posix_msg_tree_node, rb_node);
+ right_count = get_subtree_count(node->rb_right);
+
+ if (index < right_count) {
+ node = node->rb_right;
+ } else if (index < (right_count + leaf->msg_count)) {
+ /* Target is at this priority level */
+ offset = index - right_count;
+ list_for_each_entry(msg, &leaf->msg_list, m_list) {
+ if (i == offset)
+ return msg;
+ i++;
+ }
+ WARN_ON_ONCE(i != offset);
+ break;
+ } else {
+ index -= (right_count + leaf->msg_count);
+ node = node->rb_left;
+ }
+ }
+
+ return NULL;
+}
+
+static ssize_t do_mq_recvmsg2(mqd_t mqdes, struct mq_msg_attrs *args, unsigned int flags,
+ unsigned long index, ktime_t *timeout)
+{
+ ssize_t ret;
+ struct msg_msg *msg_ptr, *k_msg_buffer;
+ long k_m_type;
+ size_t k_m_ts;
+ struct inode *inode;
+ struct mqueue_inode_info *info;
+ struct timespec64 ts, *abs_timeout = NULL;
+
+ if (timeout) {
+ ts = ktime_to_timespec64(*timeout);
+ abs_timeout = &ts;
+ }
+ if (flags & MQ_PEEK) {
+ audit_mq_sendrecv(mqdes, args->msg_len, 0, abs_timeout);
+ CLASS(fd, f)(mqdes);
+ if (fd_empty(f))
+ return -EBADF;
+
+ inode = file_inode(fd_file(f));
+ if (unlikely(fd_file(f)->f_op != &mqueue_file_operations))
+ return -EBADF;
+
+ info = MQUEUE_I(inode);
+ audit_file(fd_file(f));
+ if (unlikely(!(fd_file(f)->f_mode & FMODE_READ)))
+ return -EBADF;
+
+ if (unlikely(args->msg_len < info->attr.mq_msgsize))
+ return -EMSGSIZE;
+
+ if (index >= (unsigned long)info->attr.mq_maxmsg)
+ return -EINVAL;
+
+ spin_lock(&info->lock);
+
+ if (info->attr.mq_curmsgs == 0) {
+ spin_unlock(&info->lock);
+ return -EAGAIN;
+ }
+ msg_ptr = mq_peek_index(info, index);
+ if (!msg_ptr) {
+ spin_unlock(&info->lock);
+ return -ENODATA;
+ }
+ k_m_type = msg_ptr->m_type;
+ k_m_ts = msg_ptr->m_ts;
+
+ spin_unlock(&info->lock);
+
+ k_msg_buffer = alloc_msg(k_m_ts);
+
+ if (!k_msg_buffer)
+ return -ENOMEM;
+ ret = security_msg_msg_alloc(k_msg_buffer);
+ if (ret) {
+ free_msg(k_msg_buffer);
+ return ret;
+ }
+
+ /*
+ * Two spin locks are necessary here. We are avoiding atomic memory
+ * allocation and premature allocation before confirming
+ * a message actually exists to peek and retrieving required buffer size
+ * when first lock was taken.
+ */
+ spin_lock(&info->lock);
+
+ msg_ptr = mq_peek_index(info, index);
+ if (!msg_ptr || msg_ptr->m_type != k_m_type ||
+ msg_ptr->m_ts != k_m_ts) {
+ spin_unlock(&info->lock);
+ free_msg(k_msg_buffer);
+ return -EAGAIN;
+ }
+ msg_ptr = copy_msg(msg_ptr, k_msg_buffer, k_m_ts);
+ if (IS_ERR(msg_ptr)) {
+ spin_unlock(&info->lock);
+ free_msg(k_msg_buffer);
+ return PTR_ERR(msg_ptr);
+ }
+ spin_unlock(&info->lock);
+
+ ret = k_msg_buffer->m_ts;
+ if (args->msg_prio && put_user(k_m_type, args->msg_prio)) {
+ free_msg(k_msg_buffer);
+ return -EFAULT;
+ }
+ if (store_msg((char *)args->msg_ptr, k_msg_buffer, k_m_ts)) {
+ free_msg(k_msg_buffer);
+ return -EFAULT;
+ }
+ free_msg(k_msg_buffer);
+ return ret;
+ }
+ if (flags & MQ_RECV) {
+ return do_mq_recvmsg(mqdes, (char *)args->msg_ptr, args->msg_len,
+ args->msg_prio, timeout);
+ }
+
+ return -EINVAL;
+}
+
+static int mq_mmsg_copy_attrs_from_user(struct mq_mmsg_attrs *attrs,
+ const struct mq_mmsg_attrs __user *uattrs,
+ unsigned int attrs_len)
+{
+ BUILD_BUG_ON(sizeof(*attrs) < MQ_MMSG_ATTRS_SIZE_VER0);
+ BUILD_BUG_ON(sizeof(*attrs) != MQ_MMSG_ATTRS_SIZE_LATEST);
+
+ if (unlikely(attrs_len < MQ_MMSG_ATTRS_SIZE_VER0))
+ return -EINVAL;
+ if (unlikely(attrs_len > PAGE_SIZE))
+ return -E2BIG;
+ return copy_struct_from_user(attrs, sizeof(*attrs), uattrs, attrs_len);
+}
+
+#ifdef CONFIG_COMPAT
+static int mq_mmsg_copy_compat_attrs(struct mq_mmsg_attrs *attrs,
+ const struct compat_mq_mmsg_attrs __user *uattrs,
+ unsigned int attrs_len)
+{
+ struct compat_mq_mmsg_attrs v = {};
+ int err;
+
+ BUILD_BUG_ON(sizeof(*attrs) < MQ_MMSG_ATTRS_SIZE_VER0);
+ BUILD_BUG_ON(sizeof(*attrs) != MQ_MMSG_ATTRS_SIZE_LATEST);
+ BUILD_BUG_ON(sizeof(v) != COMPAT_MQ_MMSG_ATTRS_SIZE_VER0);
+
+ if (unlikely(attrs_len < COMPAT_MQ_MMSG_ATTRS_SIZE_VER0))
+ return -EINVAL;
+ if (unlikely(attrs_len > PAGE_SIZE))
+ return -E2BIG;
+ err = copy_struct_from_user(&v, sizeof(v), uattrs, attrs_len);
+
+ if (err)
+ return err;
+ attrs->msg_attrs_vec = (struct iovec __user *)compat_ptr((unsigned long)v.msg_attrs_vec);
+ attrs->ret = (int *)compat_ptr(v.ret);
+ attrs->vlen = v.vlen;
+ return 0;
+}
+
+static int mq_mmsg_copy_compat_msg_attr(struct mq_msg_attrs *attr,
+ const struct iovec *desc_iov)
+{
+ struct compat_msg_attrs v = {};
+
+ if (desc_iov->iov_len != sizeof(v))
+ return -EINVAL;
+ if (copy_from_user(&v, desc_iov->iov_base, sizeof(v)))
+ return -EFAULT;
+
+ attr->msg_len = v.msg_len;
+ attr->msg_prio = (unsigned int *)compat_ptr(v.msg_prio);
+ attr->msg_ptr = compat_ptr(v.msg_ptr);
+ return 0;
+ }
+
+#endif
+
+static int mq_mmsg_copy_msg_attr(struct mq_msg_attrs *attr,
+ const struct iovec *desc_iov, bool compat)
+{
+ if (compat)
+ return mq_mmsg_copy_compat_msg_attr(attr, desc_iov);
+ if (desc_iov->iov_len != sizeof(*attr))
+ return -EINVAL;
+ if (copy_from_user(attr, desc_iov->iov_base, sizeof(*attr)))
+ return -EFAULT;
+ return 0;
+}
+
+static inline long mq_mmsg_done_or_error(unsigned int done, int ret)
+{
+ if (ret < 0 && done)
+ return done;
+ return ret;
+}
+
+static ssize_t do_mq_recvmmsg(mqd_t mqdes, const struct mq_mmsg_attrs *attrs,
+ unsigned int flags, unsigned long start_idx,
+ struct timespec64 *ts, bool compat)
+{
+ struct iov_iter iter;
+ struct iovec outer_iovstack[UIO_FASTIOV], *free_iov = outer_iovstack;
+ const struct iovec *msg_iov;
+ ktime_t batch_deadline, *timeout = NULL;
+ ssize_t ret = 0;
+ ssize_t batch_success = 0;
+ unsigned long index;
+ unsigned int i;
+
+ if (flags & ~MQ_VALID_FLAGS)
+ return -EINVAL;
+ if ((flags & MQ_RECV) && (flags & MQ_PEEK))
+ return -EINVAL;
+ if (start_idx > attrs->vlen)
+ return -EINVAL;
+ if (!attrs->vlen || attrs->vlen > UIO_MAXIOV)
+ return -EINVAL;
+
+ ret = __import_iovec(ITER_DEST,
+ attrs->msg_attrs_vec, attrs->vlen,
+ ARRAY_SIZE(outer_iovstack), &free_iov, &iter,
+ compat);
+ if (ret < 0)
+ return ret;
+ msg_iov = iter_iov(&iter);
+
+ /* One absolute deadline for the whole batch. */
+ if (ts) {
+ batch_deadline = timespec64_to_ktime(*ts);
+ timeout = &batch_deadline;
+ }
+ for (i = start_idx; i < attrs->vlen; i++) {
+ struct mq_msg_attrs desc = {};
+
+ ret = mq_mmsg_copy_msg_attr(&desc, &msg_iov[i], compat);
+ if (ret < 0)
+ break;
+
+ index = (flags & MQ_PEEK) ? i : 0;
+ ret = do_mq_recvmsg2(mqdes, &desc, flags, index, timeout);
+
+ if (ret < 0) {
+ if (attrs->ret && put_user(ret, attrs->ret)) {
+ kfree(free_iov);
+ return -EFAULT;
+ }
+ break;
+ }
+ batch_success++;
+ }
+
+ if (!(batch_success != attrs->vlen)) {
+ if (attrs->ret && put_user(0, attrs->ret)) {
+ kfree(free_iov);
+ return -EFAULT;
+ }
+ }
+ kfree(free_iov);
+ return mq_mmsg_done_or_error(batch_success, ret < 0 ? ret : batch_success);
+}
+
+static ssize_t do_mq_sendmmsg(mqd_t mqdes, const struct mq_mmsg_attrs *attrs,
+ unsigned long start_idx, struct timespec64 *ts,
+ bool compat)
+{
+ struct iov_iter iter;
+ struct iovec outer_iovstack[UIO_FASTIOV], *free_iov = outer_iovstack;
+ const struct iovec *msg_iov;
+ ktime_t batch_deadline, *timeout = NULL;
+ ssize_t ret = 0;
+ ssize_t batch_success = 0;
+ unsigned int i;
+
+ if (!attrs->vlen || attrs->vlen > UIO_MAXIOV || start_idx > attrs->vlen)
+ return -EINVAL;
+
+ ret = __import_iovec(ITER_SOURCE,
+ attrs->msg_attrs_vec, attrs->vlen,
+ ARRAY_SIZE(outer_iovstack), &free_iov, &iter,
+ compat);
+ if (ret < 0)
+ return ret;
+ msg_iov = iter_iov(&iter);
+
+ if (ts) {
+ batch_deadline = timespec64_to_ktime(*ts);
+ timeout = &batch_deadline;
+ }
+ for (i = start_idx; i < attrs->vlen; i++) {
+ struct mq_msg_attrs desc = {};
+ unsigned int msg_prio = 0;
+
+ ret = mq_mmsg_copy_msg_attr(&desc, &msg_iov[i], compat);
+ if (ret < 0)
+ break;
+ if (!desc.msg_prio) {
+ ret = -EINVAL;
+ break;
+ }
+ if (get_user(msg_prio, desc.msg_prio)) {
+ ret = -EFAULT;
+ break;
+ }
+ ret = do_mq_sendmsg(mqdes, desc.msg_ptr, desc.msg_len,
+ msg_prio, timeout);
+
+ if (ret < 0) {
+ if (attrs->ret && put_user(ret, attrs->ret)) {
+ kfree(free_iov);
+ return -EFAULT;
+ }
+ break;
+ }
+ batch_success++;
+ }
+
+ if (!(batch_success != attrs->vlen)) {
+ if (attrs->ret && put_user(0, attrs->ret)) {
+ kfree(free_iov);
+ return -EFAULT;
+ }
+ }
+ kfree(free_iov);
+ return mq_mmsg_done_or_error(batch_success, ret < 0 ? ret : batch_success);
+}
+
SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
size_t, msg_len, unsigned int, msg_prio,
const struct __kernel_timespec __user *, u_abs_timeout)
@@ -1244,6 +1685,27 @@ SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
}
+SYSCALL_DEFINE5(mq_sendmmsg, mqd_t, mqdes, struct mq_mmsg_attrs __user *, attrs,
+ unsigned int, attrs_len, unsigned long, start_idx,
+ const struct __kernel_timespec __user *, u_abs_timeout)
+{
+ struct mq_mmsg_attrs kattrs = {};
+ struct timespec64 ts, *p = NULL;
+ int ret;
+
+ ret = mq_mmsg_copy_attrs_from_user(&kattrs, attrs, attrs_len);
+ if (ret)
+ return ret;
+ if (u_abs_timeout) {
+ int res = prepare_timeout(u_abs_timeout, &ts);
+
+ if (res)
+ return res;
+ p = &ts;
+ }
+ return do_mq_sendmmsg(mqdes, &kattrs, start_idx, p, false);
+}
+
SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
size_t, msg_len, unsigned int __user *, u_msg_prio,
const struct __kernel_timespec __user *, u_abs_timeout)
@@ -1258,6 +1720,27 @@ SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
}
+SYSCALL_DEFINE6(mq_recvmmsg, mqd_t, mqdes, struct mq_mmsg_attrs __user *, attrs,
+ unsigned int, attrs_len, unsigned int, flags, unsigned long, start_idx,
+ const struct __kernel_timespec __user *, u_abs_timeout)
+{
+ struct mq_mmsg_attrs kattrs = {};
+ struct timespec64 ts, *p = NULL;
+ int ret;
+
+ ret = mq_mmsg_copy_attrs_from_user(&kattrs, attrs, attrs_len);
+ if (ret)
+ return ret;
+ if (u_abs_timeout) {
+ int res = prepare_timeout(u_abs_timeout, &ts);
+
+ if (res)
+ return res;
+ p = &ts;
+ }
+ return do_mq_recvmmsg(mqdes, &kattrs, flags, start_idx, p, false);
+}
+
/*
* 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.
@@ -1460,7 +1943,7 @@ struct compat_mq_attr {
};
static inline int get_compat_mq_attr(struct mq_attr *attr,
- const struct compat_mq_attr __user *uattr)
+ const struct compat_mq_attr __user *uattr)
{
struct compat_mq_attr v;
@@ -1476,7 +1959,7 @@ static inline int get_compat_mq_attr(struct mq_attr *attr,
}
static inline int put_compat_mq_attr(const struct mq_attr *attr,
- struct compat_mq_attr __user *uattr)
+ struct compat_mq_attr __user *uattr)
{
struct compat_mq_attr v;
@@ -1491,8 +1974,8 @@ static inline int put_compat_mq_attr(const struct mq_attr *attr,
}
COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
- int, oflag, compat_mode_t, mode,
- struct compat_mq_attr __user *, u_attr)
+ int, oflag, compat_mode_t, mode,
+ struct compat_mq_attr __user *, u_attr)
{
struct mq_attr attr, *p = NULL;
if (u_attr && oflag & O_CREAT) {
@@ -1504,7 +1987,7 @@ COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
}
COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
- const struct compat_sigevent __user *, u_notification)
+ const struct compat_sigevent __user *, u_notification)
{
struct sigevent n, *p = NULL;
if (u_notification) {
@@ -1541,6 +2024,56 @@ COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
return -EFAULT;
return 0;
}
+
+COMPAT_SYSCALL_DEFINE5(mq_sendmmsg, mqd_t, mqdes, struct compat_mq_mmsg_attrs __user *, attrs,
+ unsigned int, attrs_len, unsigned long, start_idx,
+ const struct __kernel_timespec __user *, u_abs_timeout)
+{
+ struct mq_mmsg_attrs kattrs = {};
+ struct timespec64 ts, *p = NULL;
+ struct iovec msg_atrrs_vec = {};
+ int ret;
+
+ kattrs.msg_attrs_vec = &msg_atrrs_vec;
+ ret = mq_mmsg_copy_compat_attrs(&kattrs, attrs, attrs_len);
+ if (ret)
+ return ret;
+
+ if (u_abs_timeout) {
+ int res = prepare_timeout(u_abs_timeout, &ts);
+
+ if (res)
+ return res;
+ p = &ts;
+ }
+
+ return do_mq_sendmmsg(mqdes, &kattrs, start_idx, p, true);
+}
+
+COMPAT_SYSCALL_DEFINE6(mq_recvmmsg, mqd_t, mqdes, struct compat_mq_mmsg_attrs __user *, attrs,
+ unsigned int, attrs_len, unsigned int, flags, unsigned long, start_idx,
+ const struct __kernel_timespec __user *, u_abs_timeout)
+{
+ struct mq_mmsg_attrs kattrs = {};
+ struct timespec64 ts, *p = NULL;
+ struct iovec msg_atrrs_vec = {};
+ int ret;
+
+ kattrs.msg_attrs_vec = &msg_atrrs_vec;
+ ret = mq_mmsg_copy_compat_attrs(&kattrs, attrs, attrs_len);
+ if (ret)
+ return ret;
+
+ if (u_abs_timeout) {
+ int res = prepare_timeout(u_abs_timeout, &ts);
+
+ if (res)
+ return res;
+ p = &ts;
+ }
+
+ return do_mq_recvmmsg(mqdes, &kattrs, flags, start_idx, p, true);
+}
#endif
#ifdef CONFIG_COMPAT_32BIT_TIME
diff --git a/ipc/msg.c b/ipc/msg.c
index 62996b97f0ac..53c1632dc22a 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -1156,7 +1156,7 @@ static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, in
* not update queue parameters.
*/
if (msgflg & MSG_COPY) {
- msg = copy_msg(msg, copy);
+ msg = copy_msg(msg, copy, min_t(size_t, bufsz, ns->msg_ctlmax));
goto out_unlock0;
}
diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index e28f0cecb2ec..a022fd36a356 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -51,7 +51,7 @@ static int __init init_msg_buckets(void)
}
subsys_initcall(init_msg_buckets);
-static struct msg_msg *alloc_msg(size_t len)
+struct msg_msg *alloc_msg(size_t len)
{
struct msg_msg *msg;
struct msg_msgseg **pseg;
@@ -122,39 +122,36 @@ struct msg_msg *load_msg(const void __user *src, size_t len)
free_msg(msg);
return ERR_PTR(err);
}
-#ifdef CONFIG_CHECKPOINT_RESTORE
-struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
+
+struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst, size_t len)
{
- struct msg_msgseg *dst_pseg, *src_pseg;
- size_t len = src->m_ts;
- size_t alen;
+ struct msg_msgseg *src_seg, *dst_seg;
+ size_t remaining, chunk;
- if (src->m_ts > dst->m_ts)
+ if (len > src->m_ts)
return ERR_PTR(-EINVAL);
- alen = min(len, DATALEN_MSG);
- memcpy(dst + 1, src + 1, alen);
+ chunk = min(len, DATALEN_MSG);
- for (dst_pseg = dst->next, src_pseg = src->next;
- src_pseg != NULL;
- dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
+ memcpy(dst + 1, src + 1, chunk);
+ remaining = len - chunk;
+ src_seg = src->next;
+ dst_seg = dst->next;
- len -= alen;
- alen = min(len, DATALEN_SEG);
- memcpy(dst_pseg + 1, src_pseg + 1, alen);
+ while (remaining > 0 && src_seg && dst_seg) {
+ chunk = min(remaining, DATALEN_SEG);
+ memcpy(dst_seg + 1, src_seg + 1, chunk);
+ remaining -= chunk;
+ src_seg = src_seg->next;
+ dst_seg = dst_seg->next;
}
-
+ if (remaining != 0)
+ return ERR_PTR(-EINVAL);
dst->m_type = src->m_type;
- dst->m_ts = src->m_ts;
-
+ dst->m_ts = len;
return dst;
}
-#else
-struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
-{
- return ERR_PTR(-ENOSYS);
-}
-#endif
+
int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
{
size_t alen;
diff --git a/ipc/util.h b/ipc/util.h
index a55d6cebe6d3..374abeee79b3 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -197,8 +197,9 @@ int ipc_parse_version(int *cmd);
extern void free_msg(struct msg_msg *msg);
extern struct msg_msg *load_msg(const void __user *src, size_t len);
-extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
+extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst, size_t len);
extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
+extern struct msg_msg *alloc_msg(size_t len);
static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
{
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index add3032da16f..8219d76c72a0 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -392,5 +392,11 @@ COND_SYSCALL(setuid16);
COND_SYSCALL(rseq);
COND_SYSCALL(rseq_slice_yield);
+/* ipc */
+COND_SYSCALL(mq_recvmmsg);
+COND_SYSCALL_COMPAT(mq_recvmmsg);
+COND_SYSCALL(mq_sendmmsg);
+COND_SYSCALL_COMPAT(mq_sendmmsg);
+
COND_SYSCALL(uretprobe);
COND_SYSCALL(uprobe);
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v4 4/4] Test: Added self-testing and documentation
2026-09-24 15:34 [PATCH v4 0/4] Add two new system call mq_recvmmsg() and mq_sendmmsg() to posix ipc mqueue mathura kumar
` (2 preceding siblings ...)
2026-09-24 15:35 ` [PATCH v4 3/4] IPC: Added system call entry in performance tool mathura kumar
@ 2026-09-24 15:35 ` mathura kumar
3 siblings, 0 replies; 5+ messages in thread
From: mathura kumar @ 2026-09-24 15:35 UTC (permalink / raw)
To: brauner; +Cc: linux-kernel, linux-arch, corbet, mathura.kumar.tech
Add test coverage to verify system call behavior under
different-different cases.
Update index documentation to include two new doc.
1) mq_recvmmsg.rst
2) mq_sendmmsg.rst
The tests validate:
1) Offset boundries.
2) Partial success behaviors.
3) Timeout behavior.
Documentation changes include:
1) Updated implementation details.
2) Error handlings mechanism.
3) Tests details.
Signed-off-by: mathura kumar <mathura.kumar.tech@gmail.com>
---
Documentation/userspace-api/index.rst | 2 +
Documentation/userspace-api/mq_recvmmsg.rst | 207 +++++++++++
Documentation/userspace-api/mq_sendmmsg.rst | 171 +++++++++
tools/testing/selftests/ipc/Makefile | 2 +-
tools/testing/selftests/ipc/mq_recvmmsg.c | 392 ++++++++++++++++++++
tools/testing/selftests/ipc/mq_sendmmsg.c | 360 ++++++++++++++++++
6 files changed, 1133 insertions(+), 1 deletion(-)
create mode 100644 Documentation/userspace-api/mq_recvmmsg.rst
create mode 100644 Documentation/userspace-api/mq_sendmmsg.rst
create mode 100644 tools/testing/selftests/ipc/mq_recvmmsg.c
create mode 100644 tools/testing/selftests/ipc/mq_sendmmsg.c
diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst
index a68b1bea57a8..4e9cbdd8c3a8 100644
--- a/Documentation/userspace-api/index.rst
+++ b/Documentation/userspace-api/index.rst
@@ -22,6 +22,8 @@ System calls
ioctl/index
mseal
rseq
+ mq_recvmmsg
+ mq_sendmmsg
Security-related interfaces
===========================
diff --git a/Documentation/userspace-api/mq_recvmmsg.rst b/Documentation/userspace-api/mq_recvmmsg.rst
new file mode 100644
index 000000000000..680e5f1beb0c
--- /dev/null
+++ b/Documentation/userspace-api/mq_recvmmsg.rst
@@ -0,0 +1,207 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+mq_recvmmsg system call
+=============================
+
+This document describes the mq_recvmmsg() system call. It provides
+an overview of the feature, interface specification, design, and
+test specification.
+
+Contents
+--------
+
+ 1) Overview
+ 2) Functional Specification
+ 3) Design
+ 4) Test Specification
+
+1) Overview
+-----------
+
+POSIX message queues on Linux provide mq_timedreceive() for consuming
+messages from a queue.This interface requires the caller to pass the
+message buffer, length and priority pointer as individual arguments to
+the system call. This imposes a fixed calling convention that cannot be
+extended without breaking the ABI.
+
+mq_recvmmsg() introduces a new system call entry point that accepts
+message buffer parameters via a struct argument inside a iovec rather
+than as individual syscall arguments.
+
+One 64-bit variant is provided with compat handling:
+ mq_recvmmsg()
+
+2) Functional Specification
+---------------------------
+
+NAME
+ mq_recvmmsg - receive or peek as a batch of messages from a
+ POSIX message queue
+
+SYNOPSIS
+
+.. code-block:: c
+
+ #include <mqueue.h>
+
+ struct mq_msg_attrs {
+ __kernel_size_t msg_len;
+ unsigned int __user *msg_prio;
+ void __user *msg_ptr;
+ };
+
+ struct mq_mmsg_attrs {
+ struct iovec __user *msg_attrs_vec;
+ __kernel_size_t vlen;
+ int *ret;
+ };
+
+ ssize_t mq_recvmmsg(mqd_t mqdes, struct mq_mmsg_attrs *attrs,
+ unsigned int attrs_len, unsigned int flags,
+ unsigned long start_idx,
+ const struct __kernel_timespec *abs_timeout);
+
+
+DESCRIPTION
+ mq_recvmmsg() receives or peeks as a batch of messages from the
+ message queue referred to by the descriptor mqdes.
+
+ The flags argument controls receive behavior. The following
+ flag is defined:
+
+ ``MQ_PEEK``
+ Copies the message into struct mq_msg_attrs without removing it from
+ the queue. The queue is not modified.
+
+ ``MQ_RECV``
+ Copies and consumes messages from the queue up to the count specified
+ by vlen.
+
+ The start_idx argument specifies which message to begin operating on within
+ the priority-ordered queue, relative to the requested batch range.
+
+ The abs_timeout argument specifies an absolute timeout for the entire batch
+ operation. When MQ_PEEK is set, abs_timeout is ignored, since peek is a
+ non-blocking snapshot operation. When MQ_PEEK is not set, abs_timeout be the
+ timeout for the entire batch.
+
+RETURN VALUE
+ On success, returns the number of messages copied into user-space.
+
+ On failure, the function returns an error directly without writing
+ to the ret field of struct mq_mmsg_attrs in two situations:
+
+ * An error occurred before a single message was successfully copied to user space.
+ * new error occurred in writing error itself in ret field of struct mq_mmsg_attrs
+ after partial success before completing batch and passing a bad address in ret can
+ cause successfully dequeued messages to be permanently lost, as userspace has no other
+ way to know about messages already dequeued in the non-peek path.
+
+
+ERRORS
+ ``EAGAIN``
+ Queue is empty and MQ_PEEK is set. Peek is always
+ non-blocking and returns immediately on empty queue.
+
+ ``EBADF``
+ mqdes is not a valid message queue descriptor open
+ for reading.
+
+ ``EFAULT``
+ attrs, msg_ptr, msg_prio, or abs_timeout points to
+ an invalid address or any invalid address.
+
+ ``EINVAL``
+ The batch size is too large, start_idx is inconsistent with the
+ current queue state, flags contains an unrecognized value, or contradictory
+ flags were passed.
+
+ ``EMSGSIZE``
+ msg_len is less than the mq_msgsize attribute of
+ the queue.
+
+ ``E2BIG``
+ attrs_len is greater than PAGE_SIZE.
+
+ ``ETIMEDOUT``
+ Pop path only. The call timed out before a message
+ became available. Never returned on peek path.
+
+ ``ENODATA``
+ No valid message exists matching the given parameters.
+
+ ``ENOMEM``
+ Insufficient memory to complete the operation.
+
+3) Design
+---------
+
+3.1 Struct-based argument passing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The message buffer parameters (msg_ptr, msg_len, msg_prio) are consolidated
+into struct mq_msg_attrs rather than passed as individual syscall arguments.
+These are then referenced via struct mq_mmsg_attrs, which contains an
+iovec msg_attrs_vec and a vlen count. The base of msg_attrs_vec holds individual
+mq_msg_attrs entries, and length store struct mq_msg_attrs size.
+
+
+3.2 Compat handling
+~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: c
+
+ struct compat_msg_attrs {
+ compat_size_t msg_len;
+ compat_uptr_t msg_prio;
+ compat_uptr_t msg_ptr;
+ };
+
+ struct compat_mq_mmsg_attrs {
+ compat_uptr_t msg_attrs_vec;
+ compat_size_t vlen;
+ compat_uptr_t ret;
+ };
+
+
+The compat entry point performs the necessary conversions before
+calling the shared do_mq_recvmmsg() implementation.
+
+3.3 Peek implementation
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+When MQ_PEEK is set, the implementation locates the target message
+in the priority tree but does not remove it. Two locks are taken:
+the first confirms a message exists before any allocation is
+attempted and retrieve required buffer size to do memory allocation
+outside of critical section, avoiding allocation on empty queues.
+The second protects the kernel temporary buffer copy operation.
+
+3.4 start_idx argument
+~~~~~~~~~~~~~~~~~~~~~~~
+
+The start_idx argument specifies which message to begin operating on within the queue.
+If a batch request fails partway through, user space is expected to supply an updated
+start_idx reflecting the number of messages already handled, failing to do so may result
+in unexpected message delivery.
+
+4) Test Specification
+----------------------
+
+Tests for mq_recvmmsg() should cover the following:
+
+1) Basic receive and peek — Verify that without MQ_PEEK the message is consumed and
+the queue depth decreases by one. Verify that the message body, priority, and return
+value are correct.
+
+2) Offset and boundary handling — Verify that the implementation correctly respects
+batch size and start_idx boundary conditions.
+
+3) Partial success — Verify that when an error occurs mid-batch, the call returns
+successfully with the count of messages processed so far, rather than discarding partial
+results.
+
+
+
+
+
diff --git a/Documentation/userspace-api/mq_sendmmsg.rst b/Documentation/userspace-api/mq_sendmmsg.rst
new file mode 100644
index 000000000000..7b676645177e
--- /dev/null
+++ b/Documentation/userspace-api/mq_sendmmsg.rst
@@ -0,0 +1,171 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+mq_sendmmsg system call
+=============================
+
+This document describes the mq_sendmmsg() system call. It provides
+an overview of the feature, interface specification, design, and
+test specification.
+
+Contents
+--------
+
+ 1) Overview
+ 2) Functional Specification
+ 3) Design
+ 4) Test Specification
+
+1) Overview
+-----------
+
+POSIX message queues on Linux provide mq_timedsend() for storing
+messages in a queue one at time.
+
+mq_sendmmsg() introduces a new system call entry point that take
+messages in batch and store in queues.
+
+One 64-bit variant is provided with compat handling:
+ mq_sendmmsg()
+
+2) Functional Specification
+---------------------------
+
+NAME
+ mq_sendmmsg - send messages as a batch to queues.
+
+SYNOPSIS
+
+.. code-block:: c
+
+ #include <mqueue.h>
+
+ struct mq_msg_attrs {
+ __kernel_size_t msg_len;
+ unsigned int __user *msg_prio;
+ void __user *msg_ptr;
+ };
+
+ struct mq_mmsg_attrs {
+ struct iovec __user *msg_attrs_vec;
+ __kernel_size_t vlen;
+ int *ret;
+ };
+
+ ssize_t mq_sendmmsg(mqd_t mqdes, struct mq_mmsg_attrs *attrs,
+ unsigned int attrs_len, unsigned long start_idx,
+ const struct __kernel_timespec *abs_timeout);
+
+
+DESCRIPTION
+ mq_sendmmsg() send messages in batch to message queue referred
+ to by the descriptor mqdes.
+
+ The start_idx argument specifies which message to begin operating on within
+ relative to the requested batch range.
+
+ The abs_timeout argument specifies an absolute timeout for the entire batch
+ operation.
+
+RETURN VALUE
+ On success, returns the number of messages stored into the queues.
+
+ On failure, the function returns an error directly without writing
+ to the ret field of struct mq_mmsg_attrs in two situations:
+
+ * An error occurred before a single message was successfully stored into the queues.
+ * A new error occurred in writing error itself in ret field of struct mq_mmsg_attrs
+ after partial success before completing batch and passing a bad address in ret can
+ cause successfully enqueued messages to be processed again in a future call, resulting
+ in duplicates, as userspace has no other way to know about messages processed so far in
+ previous call.
+
+
+ERRORS
+ ``EAGAIN``
+ Queue is not empty.
+
+ ``EBADF``
+ mqdes is not a valid message queue descriptor open
+ for reading.
+
+ ``EFAULT``
+ attrs, msg_ptr, msg_prio, or abs_timeout points to
+ an invalid address.
+
+ ``EINVAL``
+ The batch size is too large, start_idx is inconsistent with the
+ current queue state.
+
+ ``EMSGSIZE``
+ msg_len is greater than the mq_msgsize attribute of
+ the queue.
+
+ ``E2BIG``
+ attrs_len is greater than PAGE_SIZE.
+
+ ``ETIMEDOUT``
+ The call timed out before a space became available to store
+ new messages.
+
+ ``ENOMEM``
+ Insufficient memory to complete the operation.
+
+3) Design
+---------
+
+3.1 Struct-based argument passing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The message buffer parameters (msg_ptr, msg_len, msg_prio) are consolidated
+into struct mq_msg_attrs rather than passed as individual syscall arguments.
+These are then referenced via struct mq_mmsg_attrs, which contains an
+iovec msg_attrs_vec and a vlen count. The base of msg_attrs_vec holds individual
+mq_msg_attrs entries, and length store struct mq_msg_attrs size.
+
+
+3.2 Compat handling
+~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: c
+
+ struct compat_msg_attrs {
+ compat_size_t msg_len;
+ compat_uptr_t msg_prio;
+ compat_uptr_t msg_ptr;
+ };
+
+ struct compat_mq_mmsg_attrs {
+ compat_uptr_t msg_attrs_vec;
+ compat_size_t vlen;
+ compat_uptr_t ret;
+ };
+
+
+The compat entry point performs the necessary conversions before
+calling the shared do_mq_sendmmsg() implementation.
+
+
+3.3 start_idx argument
+~~~~~~~~~~~~~~~~~~~~~~~
+
+The start_idx argument specifies the message at which to begin storing messages in the queue.
+If a batch request fails partway through, user space is expected to supply an updated
+start_idx reflecting the number of messages already handled, failing to do so may result
+in duplicate message passed to the queues.
+
+4) Test Specification
+----------------------
+
+Tests for mq_sendmmsg() should cover the following:
+
+1) Offset and boundary handling — Verify that the implementation work correctly as per
+batch size and start_idx boundary conditions.
+
+2) Partial success — Verify that when an error occurs mid-batch, the call returns
+successfully with the count of messages processed so far.
+
+3) Batch Timeout - Verify batch absolute deadline return expected value when
+queue is completely full.
+
+
+
diff --git a/tools/testing/selftests/ipc/Makefile b/tools/testing/selftests/ipc/Makefile
index fad10f2bb57b..04da0efd67d7 100644
--- a/tools/testing/selftests/ipc/Makefile
+++ b/tools/testing/selftests/ipc/Makefile
@@ -12,7 +12,7 @@ endif
CFLAGS += $(KHDR_INCLUDES)
-TEST_GEN_PROGS := msgque
+TEST_GEN_PROGS := msgque mq_recvmmsg mq_sendmmsg
include ../lib.mk
diff --git a/tools/testing/selftests/ipc/mq_recvmmsg.c b/tools/testing/selftests/ipc/mq_recvmmsg.c
new file mode 100644
index 000000000000..7d464c4d839f
--- /dev/null
+++ b/tools/testing/selftests/ipc/mq_recvmmsg.c
@@ -0,0 +1,392 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/uio.h>
+#include <time.h>
+#include <unistd.h>
+#include <linux/time_types.h>
+#include "kselftest.h"
+#include <mqueue.h>
+
+#ifndef __NR_mq_recvmmsg
+#if defined(__alpha__)
+#define __NR_mq_recvmmsg 582
+#else
+#define __NR_mq_recvmmsg 472
+#endif
+#endif
+
+#define MQ_PEEK 0x02
+#define MQ_RECV 0x04
+
+#define MQ_NAME_PREFIX "/mq_peek_test"
+#define MQ_MAXMSG 16
+#define MAX_MSG_SIZE 8192
+
+struct msg_attrs {
+ long msg_len;
+ unsigned int *msg_prio;
+ void *msg_ptr;
+};
+
+struct mmsg_attrs {
+ struct iovec *msg_attrs_vec;
+ long vlen;
+ int *err;
+};
+
+struct batch_slot {
+ struct msg_attrs desc;
+ struct iovec iov;
+ char buf[MAX_MSG_SIZE];
+ unsigned int prio;
+};
+
+static long mq_recvmmsg(mqd_t mqdes, struct mmsg_attrs *attrs, unsigned int attrs_len,
+ unsigned int flags, unsigned int start_idx,
+ const struct __kernel_timespec *timeout)
+{
+ return syscall(__NR_mq_recvmmsg, mqdes, attrs, attrs_len, flags,
+ start_idx, timeout);
+}
+
+static long queue_depth(mqd_t mqd)
+{
+ struct mq_attr attr;
+
+ if (mq_getattr(mqd, &attr))
+ return -1;
+
+ return attr.mq_curmsgs;
+}
+
+static mqd_t open_queue(const char *suffix)
+{
+ static unsigned int seq;
+ char name[128];
+ struct mq_attr attr = {
+ .mq_flags = 0,
+ .mq_maxmsg = MQ_MAXMSG,
+ .mq_msgsize = MAX_MSG_SIZE,
+ };
+
+ mqd_t mqd;
+
+ snprintf(name, sizeof(name), "%s%s_%d_%u", MQ_NAME_PREFIX, suffix, getpid(),
+ seq++);
+
+ mq_unlink(name);
+
+ mqd = mq_open(name, O_NONBLOCK | O_RDWR | O_CREAT | O_EXCL, 0600, &attr);
+ if (mqd == (mqd_t)-1) {
+ ksft_test_result_fail("mq_open(%s) failed: %m\n", name);
+ ksft_exit_fail();
+ }
+
+ mq_unlink(name);
+ return mqd;
+}
+
+static void build_slot(struct batch_slot *slot)
+{
+ memset(slot, 0, sizeof(*slot));
+ slot->desc.msg_len = sizeof(slot->buf);
+ slot->desc.msg_prio = &slot->prio;
+ slot->desc.msg_ptr = slot->buf;
+ slot->iov.iov_base = &slot->desc;
+ slot->iov.iov_len = sizeof(slot->desc);
+}
+
+static void build_slots(struct batch_slot *slots, size_t nr)
+{
+ size_t i;
+
+ for (i = 0; i < nr; i++)
+ build_slot(&slots[i]);
+}
+
+static long batch_recv(mqd_t mqd, struct batch_slot *slots, size_t nr,
+ int *err, unsigned int flags, unsigned int start_idx,
+ const struct __kernel_timespec *timeout)
+{
+ struct iovec vec[MQ_MAXMSG];
+ struct mmsg_attrs attrs;
+ size_t i;
+
+ for (i = 0; i < nr; i++)
+ vec[i] = slots[i].iov;
+
+ attrs.msg_attrs_vec = vec;
+ attrs.vlen = nr;
+ attrs.err = err;
+
+ return mq_recvmmsg(mqd, &attrs, sizeof(attrs), flags, start_idx,
+ timeout);
+}
+
+
+static void send_or_die(mqd_t mqd, unsigned int prio, const char *payload)
+{
+ if (mq_send(mqd, payload, strlen(payload), prio)) {
+ ksft_test_result_fail("mq_send(%s, %u) failed: %m\n",
+ payload, prio);
+ ksft_exit_fail();
+ }
+}
+
+static bool check_slot(const struct batch_slot *slot, const char *payload,
+ unsigned int prio)
+{
+ size_t len = strlen(payload);
+
+ if (slot->prio != prio)
+ return false;
+ if (memcmp(slot->buf, payload, len))
+ return false;
+ return true;
+}
+
+static void test_peek_batch_success_count(void)
+{
+ mqd_t mqd = open_queue("peek_count");
+ struct batch_slot slots[3];
+ long ret;
+ int err;
+
+ send_or_die(mqd, 1, "low");
+ send_or_die(mqd, 9, "high");
+
+ build_slots(slots, ARRAY_SIZE(slots));
+ ret = batch_recv(mqd, slots, ARRAY_SIZE(slots), &err, MQ_PEEK, 0, NULL);
+
+ if (ret != 2) {
+ ksft_test_result_fail("peek count: ret=%ld expected=2\n", ret);
+ goto out;
+ }
+ if (!check_slot(&slots[0], "high", 9) ||
+ !check_slot(&slots[1], "low", 1)) {
+ ksft_test_result_fail("peek count: payload/prio mismatch\n");
+ goto out;
+ }
+ if (queue_depth(mqd) != 2) {
+ ksft_test_result_fail("peek count: queue depth changed to %ld\n",
+ queue_depth(mqd));
+ goto out;
+ }
+
+ ksft_test_result_pass("peek batch returns number of successful messages\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_receive_batch_success_count(void)
+{
+ static const struct __kernel_timespec expired = { 0, 0 };
+ mqd_t mqd = open_queue("recv_count");
+ struct batch_slot slots[3];
+ long ret;
+ int err;
+
+ send_or_die(mqd, 2, "two");
+ send_or_die(mqd, 7, "seven");
+
+ build_slots(slots, ARRAY_SIZE(slots));
+ ret = batch_recv(mqd, slots, ARRAY_SIZE(slots), &err, MQ_RECV, 0, &expired);
+
+ if (ret != 2) {
+ ksft_test_result_fail("receive count: ret=%ld expected=2\n", ret);
+ goto out;
+ }
+ if (!check_slot(&slots[0], "seven", 7) ||
+ !check_slot(&slots[1], "two", 2)) {
+ ksft_test_result_fail("receive count: payload/prio mismatch\n");
+ goto out;
+ }
+ if (queue_depth(mqd) != 0) {
+ ksft_test_result_fail("receive count: queue depth=%ld expected=0\n",
+ queue_depth(mqd));
+ goto out;
+ }
+
+ ksft_test_result_pass("receive batch returns success count and consumes messages\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_peek_start_idx_uses_absolute_index(void)
+{
+ mqd_t mqd = open_queue("peek_offset");
+ struct batch_slot slots[3];
+ long ret;
+ int err;
+
+ send_or_die(mqd, 9, "high");
+ send_or_die(mqd, 5, "mid");
+ send_or_die(mqd, 1, "low");
+
+ build_slots(slots, ARRAY_SIZE(slots));
+ memset(slots[0].buf, 0x5a, sizeof(slots[0].buf));
+ ret = batch_recv(mqd, slots, ARRAY_SIZE(slots), &err, MQ_PEEK, 1, NULL);
+
+ if (ret != 2) {
+ ksft_test_result_fail("peek start_idx: ret=%ld expected=2\n", ret);
+ goto out;
+ }
+ if (!check_slot(&slots[1], "mid", 5) ||
+ !check_slot(&slots[2], "low", 1)) {
+ ksft_test_result_fail("peek start_idx: wrong messages returned\n");
+ goto out;
+ }
+ if (slots[0].buf[0] != 0x5a) {
+ ksft_test_result_fail("peek start_idx: slot 0 was written by kernel unnecessarily\n");
+ goto out;
+ }
+
+ ksft_test_result_pass("peek start_idx maps directly to queue\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_receive_start_idx_not_receives_from_outside_range(void)
+{
+ mqd_t mqd = open_queue("recv_offset");
+ struct batch_slot slots[3];
+ long ret;
+ int err;
+
+ send_or_die(mqd, 8, "first");
+ send_or_die(mqd, 3, "second");
+
+ build_slots(slots, ARRAY_SIZE(slots));
+ memset(slots[0].buf, 0x6b, sizeof(slots[0].buf));
+ ret = batch_recv(mqd, slots, ARRAY_SIZE(slots), &err, MQ_RECV, 1, NULL);
+
+ if (ret != 2) {
+ ksft_test_result_fail("receive start_idx: ret=%ld expected=2\n",
+ ret);
+ goto out;
+ }
+ if (!check_slot(&slots[1], "first", 8) ||
+ !check_slot(&slots[2], "second", 3)) {
+ ksft_test_result_fail("receive start_idx: wrong receive order\n");
+ goto out;
+ }
+ if (slots[0].buf[0] != 0x6b) {
+ ksft_test_result_fail("receive start_idx: slot 0 was written by kernel unnecessarily\n");
+ goto out;
+ }
+
+ ksft_test_result_pass("non-peek path ignores queue indexing and receives from head within range\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_peek_partial_success_on_small_buffer(void)
+{
+ mqd_t mqd = open_queue("peek_small");
+ struct batch_slot slots[2];
+ long ret;
+ int err;
+
+ send_or_die(mqd, 9, "abc");
+ send_or_die(mqd, 4, "1234");
+
+ build_slots(slots, ARRAY_SIZE(slots));
+ slots[1].desc.msg_len = 1;
+ ret = batch_recv(mqd, slots, ARRAY_SIZE(slots), &err, MQ_PEEK, 0, NULL);
+
+ if (ret != 1) {
+ ksft_test_result_fail("peek partial small buffer: ret=%ld expected=1\n",
+ ret);
+ goto out;
+ }
+ if (!check_slot(&slots[0], "abc", 9)) {
+ ksft_test_result_fail("peek partial small buffer: first slot mismatch\n");
+ goto out;
+ }
+ if (queue_depth(mqd) != 2) {
+ ksft_test_result_fail("peek partial small buffer: queue depth=%ld expected=2\n",
+ queue_depth(mqd));
+ goto out;
+ }
+
+ ksft_test_result_pass("peek batch reports completed so far before EMSGSIZE\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_receive_partial_success_on_bad_desc_len(void)
+{
+ mqd_t mqd = open_queue("recv_desc");
+ struct batch_slot slots[2];
+ long ret;
+ int err;
+
+ send_or_die(mqd, 6, "driver");
+ send_or_die(mqd, 2, "module");
+
+ build_slots(slots, ARRAY_SIZE(slots));
+ slots[1].iov.iov_len = sizeof(slots[1].desc) - 1;
+ ret = batch_recv(mqd, slots, ARRAY_SIZE(slots), &err, MQ_RECV, 0, NULL);
+
+ if (ret != 1) {
+ ksft_test_result_fail("receive partial desc len: ret=%ld expected=1\n",
+ ret);
+ goto out;
+ }
+ if (!check_slot(&slots[0], "driver", 6)) {
+ ksft_test_result_fail("receive partial desc len: first slot mismatch\n");
+ goto out;
+ }
+ if (queue_depth(mqd) != 1) {
+ ksft_test_result_fail("receive partial desc len: queue depth=%ld expected=1\n",
+ queue_depth(mqd));
+ goto out;
+ }
+
+ ksft_test_result_pass("receive batch reports completed so far before descriptor error\n");
+out:
+ mq_close(mqd);
+}
+
+static const struct {
+ const char *name;
+ void (*fn)(void);
+} tests[] = {
+ { "peek batch success count", test_peek_batch_success_count },
+ { "receive batch success count", test_receive_batch_success_count },
+ { "peek absolute index with start_idx", test_peek_start_idx_uses_absolute_index },
+ { "receive start_idx obey offset boundary", test_receive_start_idx_not_receives_from_outside_range },
+ { "peek partial success before EMSGSIZE", test_peek_partial_success_on_small_buffer },
+ { "receive partial success before desc error", test_receive_partial_success_on_bad_desc_len },
+};
+
+int main(void)
+{
+ size_t i;
+ struct batch_slot probe;
+ long ret;
+ int err;
+
+ ksft_print_header();
+
+ build_slot(&probe);
+ ret = batch_recv((mqd_t)-1, &probe, 1, &err, MQ_PEEK, 0, NULL);
+ if (ret == -1 && errno == ENOSYS)
+ ksft_exit_skip("mq_recvmmsg syscall not available\n");
+
+ ksft_set_plan(ARRAY_SIZE(tests));
+
+ for (i = 0; i < ARRAY_SIZE(tests); i++) {
+ ksft_print_msg("[%02zu] %s\n", i + 1, tests[i].name);
+ tests[i].fn();
+ }
+
+ return ksft_get_fail_cnt() ? 1 : 0;
+}
diff --git a/tools/testing/selftests/ipc/mq_sendmmsg.c b/tools/testing/selftests/ipc/mq_sendmmsg.c
new file mode 100644
index 000000000000..3f51ba75d1cb
--- /dev/null
+++ b/tools/testing/selftests/ipc/mq_sendmmsg.c
@@ -0,0 +1,360 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <fcntl.h>
+#include <mqueue.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/uio.h>
+#include <time.h>
+#include <unistd.h>
+#include <linux/time_types.h>
+#include "kselftest.h"
+
+#ifndef __NR_mq_sendmmsg
+#if defined(__alpha__)
+#define __NR_mq_sendmmsg 583
+#else
+#define __NR_mq_sendmmsg 473
+#endif
+#endif
+
+#define MQ_NAME_PREFIX "/mq_sendmmsg_test_"
+#define MQ_MAXMSG 16
+#define MAX_MSG_SIZE 128
+
+struct msg_attrs {
+ long msg_len;
+ unsigned int *msg_prio;
+ void *msg_ptr;
+};
+
+struct mmsg_attrs {
+ struct iovec *msg_attrs_vec;
+ long vlen;
+ int *err;
+};
+
+struct send_slot {
+ struct msg_attrs desc;
+ struct iovec iov;
+ const char *payload;
+ unsigned int prio;
+};
+
+static long mq_sendmmsg(mqd_t mqdes, struct mmsg_attrs *attrs,
+ unsigned int attrs_len, unsigned long start_idx,
+ const struct __kernel_timespec *timeout)
+{
+ return syscall(__NR_mq_sendmmsg, mqdes, attrs, attrs_len, start_idx,
+ timeout);
+}
+
+static mqd_t open_queue_rw(const char *suffix, unsigned int O_FLAGS, long maxmsg)
+{
+ static unsigned int seq;
+ char name[128];
+ struct mq_attr attr = {
+ .mq_flags = 0,
+ .mq_maxmsg = maxmsg,
+ .mq_msgsize = MAX_MSG_SIZE,
+ };
+
+ mqd_t mqd;
+
+ snprintf(name, sizeof(name), "%s%s_%d_%u", MQ_NAME_PREFIX, suffix, getpid(), seq++);
+ mq_unlink(name);
+
+ mqd = mq_open(name, O_FLAGS, 0600, &attr);
+ if (mqd == (mqd_t)-1) {
+ ksft_test_result_fail("mq_open(%s) failed: %m\n", name);
+ ksft_exit_fail();
+ }
+
+ mq_unlink(name);
+ return mqd;
+}
+
+static void init_send_slot(struct send_slot *slot, const char *payload,
+ unsigned int prio)
+{
+ memset(slot, 0, sizeof(*slot));
+ slot->payload = payload;
+ slot->prio = prio;
+ slot->desc.msg_len = strlen(payload);
+ slot->desc.msg_prio = &slot->prio;
+ slot->desc.msg_ptr = (void *)payload;
+ slot->iov.iov_base = &slot->desc;
+ slot->iov.iov_len = sizeof(slot->desc);
+}
+
+static void init_send_slots(struct send_slot *slots, char *const *payloads,
+ const unsigned int *prios, size_t nr)
+{
+ size_t i;
+
+ for (i = 0; i < nr; i++)
+ init_send_slot(&slots[i], payloads[i], prios[i]);
+}
+
+static long batch_send(mqd_t mqd, struct send_slot *slots, size_t nr, int *err,
+ unsigned int start_idx,
+ const struct __kernel_timespec *timeout)
+{
+ struct iovec vec[MQ_MAXMSG];
+ struct mmsg_attrs attrs;
+ size_t i;
+
+ for (i = 0; i < nr; i++)
+ vec[i] = slots[i].iov;
+
+ attrs.msg_attrs_vec = vec;
+ attrs.vlen = nr;
+ attrs.err = err;
+
+ return mq_sendmmsg(mqd, &attrs, sizeof(attrs), start_idx, timeout);
+}
+
+static long queue_depth(mqd_t mqd)
+{
+ struct mq_attr attr;
+
+ if (mq_getattr(mqd, &attr))
+ return -1;
+
+ return attr.mq_curmsgs;
+}
+
+static bool recv_expect(mqd_t mqd, const char *payload, unsigned int prio)
+{
+ char buf[MAX_MSG_SIZE];
+ unsigned int got_prio = 0;
+ ssize_t ret;
+ size_t len = strlen(payload);
+
+ memset(buf, 0, sizeof(buf));
+ ret = mq_receive(mqd, buf, sizeof(buf), &got_prio);
+ if (ret < 0)
+ return false;
+ if ((size_t)ret != len)
+ return false;
+ if (got_prio != prio)
+ return false;
+ if (memcmp(buf, payload, len))
+ return false;
+ return true;
+}
+
+static void test_start_idx_obeys_offset(void)
+{
+ mqd_t mqd = open_queue_rw("offset", O_NONBLOCK | O_RDWR | O_CREAT | O_EXCL, MQ_MAXMSG);
+ struct send_slot slots[3];
+ static char *const payloads[] = { "first", "second", "third" };
+ unsigned int prios[] = { 1, 5, 9 };
+ long ret;
+ int err;
+
+ init_send_slots(slots, payloads, prios, ARRAY_SIZE(slots));
+ ret = batch_send(mqd, slots, ARRAY_SIZE(slots), &err, 1, NULL);
+
+ if (ret != 2) {
+ ksft_test_result_fail("start_idx skip: ret=%ld expected=2\n", ret);
+ goto out;
+ }
+ if (queue_depth(mqd) != 2) {
+ ksft_test_result_fail("start_idx skip: queue depth=%ld expected=2\n",
+ queue_depth(mqd));
+ goto out;
+ }
+ if (!recv_expect(mqd, "third", 9) ||
+ !recv_expect(mqd, "second", 5)) {
+ ksft_test_result_fail("start_idx skip: wrong messages sent\n");
+ goto out;
+ }
+
+ ksft_test_result_pass("start_idx skips earlier descriptors\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_partial_success_on_null_prio(void)
+{
+ mqd_t mqd = open_queue_rw("null_prio", O_NONBLOCK | O_RDWR | O_CREAT | O_EXCL, MQ_MAXMSG);
+ struct send_slot slots[2];
+ static char *const payloads[] = { "ok", "bad" };
+ unsigned int prios[] = { 7, 3 };
+ long ret;
+ int err;
+
+ init_send_slots(slots, payloads, prios, ARRAY_SIZE(slots));
+ slots[1].desc.msg_prio = NULL;
+ ret = batch_send(mqd, slots, ARRAY_SIZE(slots), &err, 0, NULL);
+
+ if (ret != 1) {
+ ksft_test_result_fail("partial null prio: ret=%ld expected=1\n", ret);
+ goto out;
+ }
+ if (queue_depth(mqd) != 1 || !recv_expect(mqd, "ok", 7)) {
+ ksft_test_result_fail("partial null prio: queue contents mismatch\n");
+ goto out;
+ }
+
+ ksft_test_result_pass("completed prefix is returned before NULL prio error\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_partial_success_on_bad_desc_len(void)
+{
+ mqd_t mqd = open_queue_rw("bad_desc", O_NONBLOCK | O_RDWR | O_CREAT | O_EXCL, MQ_MAXMSG);
+ struct send_slot slots[2];
+ static char *const payloads[] = { "ok", "bad" };
+ unsigned int prios[] = { 8, 2 };
+ long ret;
+ int err;
+
+ init_send_slots(slots, payloads, prios, ARRAY_SIZE(slots));
+ slots[1].iov.iov_len = sizeof(slots[1].desc) - 1;
+ ret = batch_send(mqd, slots, ARRAY_SIZE(slots), &err, 0, NULL);
+
+ if (ret != 1) {
+ ksft_test_result_fail("partial bad desc len: ret=%ld expected=1\n", ret);
+ goto out;
+ }
+ if (queue_depth(mqd) != 1 || !recv_expect(mqd, "ok", 8)) {
+ ksft_test_result_fail("partial bad desc len: queue contents mismatch\n");
+ goto out;
+ }
+
+ ksft_test_result_pass("completed prefix is returned before descriptor error\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_partial_success_on_bad_prio_ptr(void)
+{
+ mqd_t mqd = open_queue_rw("bad_prio_ptr", O_NONBLOCK | O_RDWR | O_CREAT | O_EXCL, MQ_MAXMSG);
+ struct send_slot slots[2];
+ static char *const payloads[] = { "ok", "bad" };
+ unsigned int prios[] = { 6, 4 };
+ long ret;
+ int err;
+
+ init_send_slots(slots, payloads, prios, ARRAY_SIZE(slots));
+ slots[1].desc.msg_prio = (void *)1;
+ ret = batch_send(mqd, slots, ARRAY_SIZE(slots), &err, 0, NULL);
+
+ if (ret != 1) {
+ ksft_test_result_fail("partial bad prio ptr: ret=%ld expected=1\n", ret);
+ goto out;
+ }
+ if (queue_depth(mqd) != 1 || !recv_expect(mqd, "ok", 6)) {
+ ksft_test_result_fail("partial bad prio ptr: queue contents mismatch\n");
+ goto out;
+ }
+
+ ksft_test_result_pass("completed prefix is returned before bad prio pointer fault\n");
+out:
+ mq_close(mqd);
+}
+
+static void test_full_queue_timeout(void)
+{
+ static const struct __kernel_timespec expired = { 0, 0 };
+ mqd_t mqd = open_queue_rw("full_timeout", O_RDWR | O_CREAT | O_EXCL, 1);
+ struct send_slot slot;
+ long ret;
+ int err;
+
+ init_send_slot(&slot, "first", 1);
+ ret = batch_send(mqd, &slot, 1, &err, 0, NULL);
+ if (ret != 1)
+ ksft_exit_fail_msg("failed to prefill queue\n");
+
+ init_send_slot(&slot, "second", 2);
+ ret = batch_send(mqd, &slot, 1, &err, 0, &expired);
+
+ if (ret == -1 && errno == ETIMEDOUT && queue_depth(mqd) == 1)
+ ksft_test_result_pass("full queue with expired timeout returns ETIMEDOUT\n");
+ else
+ ksft_test_result_fail("full queue timeout: ret=%ld errno=%d depth=%ld\n",
+ ret, errno, queue_depth(mqd));
+
+ mq_close(mqd);
+}
+
+static void test_partial_success_when_queue_fills(void)
+{
+ static const struct __kernel_timespec expired = { 0, 0 };
+ mqd_t mqd = open_queue_rw("queue_fills", O_NONBLOCK | O_RDWR | O_CREAT | O_EXCL, 2);
+ struct send_slot slots[2];
+ static char *const payloads[] = { "fit", "overflow" };
+ unsigned int prios[] = { 1, 2 };
+ long ret;
+ int err;
+
+ init_send_slot(&slots[0], "prefill", 3);
+ ret = batch_send(mqd, &slots[0], 1, &err, 0, NULL);
+ if (ret != 1)
+ ksft_exit_fail_msg("failed to prefill queue\n");
+
+ init_send_slots(slots, payloads, prios, ARRAY_SIZE(slots));
+ ret = batch_send(mqd, slots, ARRAY_SIZE(slots), &err, 0, &expired);
+
+ if (ret != 1) {
+ ksft_test_result_fail("queue fills partial: ret=%ld expected=1\n", ret);
+ goto out;
+ }
+ if (queue_depth(mqd) != 2) {
+ ksft_test_result_fail("queue fills partial: depth=%ld expected=2\n",
+ queue_depth(mqd));
+ goto out;
+ }
+ if (!recv_expect(mqd, "prefill", 3) || !recv_expect(mqd, "fit", 1)) {
+ ksft_test_result_fail("queue fills partial: queue contents mismatch\n");
+ goto out;
+ }
+
+ ksft_test_result_pass("completed operation is returned when queue fills mid-batch\n");
+out:
+ mq_close(mqd);
+}
+
+static const struct {
+ const char *name;
+ void (*fn)(void);
+} tests[] = {
+ { "start_idx obey offset", test_start_idx_obeys_offset },
+ { "partial success on NULL prio", test_partial_success_on_null_prio },
+ { "partial success on bad desc len", test_partial_success_on_bad_desc_len },
+ { "partial success on bad prio pointer", test_partial_success_on_bad_prio_ptr },
+ { "full queue timeout", test_full_queue_timeout },
+ { "partial success when queue fills", test_partial_success_when_queue_fills },
+};
+
+int main(void)
+{
+ size_t i;
+ struct send_slot probe;
+ long ret;
+ int err;
+
+ ksft_print_header();
+
+ init_send_slot(&probe, "probe", 1);
+ ret = batch_send((mqd_t)-1, &probe, 1, &err, 0, NULL);
+ if (ret == -1 && errno == ENOSYS)
+ ksft_exit_skip("mq_sendmmsg syscall not available\n");
+
+ ksft_set_plan(ARRAY_SIZE(tests));
+
+ for (i = 0; i < ARRAY_SIZE(tests); i++) {
+ ksft_print_msg("[%02zu] %s\n", i + 1, tests[i].name);
+ tests[i].fn();
+ }
+
+ return ksft_get_fail_cnt() ? 1 : 0;
+}
--
2.43.0
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