Re: [PATCH RESEND v2 1/4]IPC: Added New system call do_mq_timedreceive2() for non-destructive peek on posix mqueue

[Jonathan Corbet <corbet@lwn.net>]

One other thing I noticed ...

Mathura_Kumar <academic1mathura@gmail.com> writes:

> Signed-off-by: Mathura_Kumar <academic1mathura@gmail.com>
> ---
>  include/linux/compat.h            |   6 +-
>  include/linux/syscalls.h          |   6 +
>  include/uapi/asm-generic/unistd.h |   7 +-
>  include/uapi/linux/mqueue.h       |  14 ++-
>  ipc/mqueue.c                      | 186 ++++++++++++++++++++++++++++--
>  ipc/msg.c                         |   2 +-
>  ipc/msgutil.c                     |  48 ++++----
>  ipc/util.h                        |   3 +-
>  kernel/sys_ni.c                   |   1 +
>  9 files changed, 231 insertions(+), 42 deletions(-)

[...]

> +static int do_mq_timedreceive2(mqd_t mqdes, struct mq_timedreceive2_args *args,
> +			       unsigned int flags, unsigned long index,
> +			       struct timespec64 *ts)
> +{
> +	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;
> +
> +	if (!(flags & MQ_PEEK)) {
> +		return do_mq_timedreceive(mqdes, args->msg_ptr, args->msg_len,
> +					  args->msg_prio, ts);
> +	}

You don't check for unknown flags here; that will make impossible to add
new flags in the future.

jon