From: Cyril Hrubis <chrubis@xxxxxxx>
Signed-off-by: Cyril Hrubis <chrubis@xxxxxxx>
---
man2/ioctl_pipe.2 | 75 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 75 insertions(+)
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+.\" Copyright (c) 2022 by Cyril Hrubis <chrubi@xxxxxxx>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date. The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein. The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
+.\"
+.\"
+.TH IOCTL_PIPE 2 2022-08-06 "Linux" "Linux Programmer's Manual"
+.SH NAME
+ioctl_pipe \- ioctl() operations for General notification mechanism
+.SH SYNOPSIS
+.nf
+.B #include <linux/watch_queue.h>
+.PP
+.BI "int ioctl(int " pipefd[1] ", IOC_WATCH_QUEUE_SET_SIZE, int " size ");
+.PP
+.BI "int ioctl(int " pipefd[1] ", IOC_WATCH_QUEUE_SET_FILTER, struct watch_notification_filter * " filter ");
+.fi
+.PP
+.SH DESCRIPTION
+The following
+.BR ioctl (2)
+operations are provided to set up a general notification queue parameters.
+The notification queue is build on the top of a
+.BR pipe (2)
+opened with
+.B O_NOTIFICATION_PIPE
+flag.
+.TP
+.BR IOC_WATCH_QUEUE_SET_SIZE " (since Linux 5.8)"
+.\" commit c73be61cede5882f9605a852414db559c0ebedfd
+Preallocates the pipe buffer memory so that it can fit size notification messages. Currently the size must be between 1 and 512.
+.TP
+.BR IOC_WATCH_QUEUE_SET_FILTER " (since Linux 5.8)"
+.\" commit c73be61cede5882f9605a852414db559c0ebedfd
+Watch queue filter, if set, can limit events that are received.
+Filters are passed in a \fIstruct watch_notification_filter\fP
+and each filter is described by \fIstruct watch_notification_type_filter\fP structure.
+
+.EX
+struct watch_notification_filter {
+ __u32 nr_filters;
+ __u32 __reserved;
+ struct watch_notification_type_filter filters[];
+};
+
+struct watch_notification_type_filter {
+ __u32 type;
+ __u32 info_filter;
+ __u32 info_mask;
+ __u32 subtype_filter[8];
+};
+.EE
+
+.SH SEE ALSO
+.BR pipe (2),
+.BR ioctl (2)
--
2.35.1
