NAME

       ioctl_pipe - ioctl() operations for General notification mechanism

SYNOPSIS

       #include <linux/watch_queue.h>  /* Definition of IOC_WATCH_QUEUE_* */
       #include <sys/ioctl.h>

       int ioctl(int pipefd[1], IOC_WATCH_QUEUE_SET_SIZE, int size);
       int ioctl(int pipefd[1], IOC_WATCH_QUEUE_SET_FILTER,
                 struct watch_notification_filter *filter);

DESCRIPTION

       The  following  ioctl(2)  operations  are  provided to set up general notification queue parameters.  The
       notification queue is built on the top of a pipe(2) opened with the O_NOTIFICATION_PIPE flag.

       IOC_WATCH_QUEUE_SET_SIZE (since Linux 5.8)
              Preallocates the pipe buffer memory so that it can fit  size  notification  messages.   Currently,
              size must be between 1 and 512.

       IOC_WATCH_QUEUE_SET_FILTER (since Linux 5.8)
              Watch  queue  filter  can  limit  events  that  are  received.   Filters  are  passed  in a struct
              watch_notification_filter and each filter is described by a struct  watch_notification_type_filter
              structure.

                  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];
                  };

SEE ALSO

       pipe(2), ioctl(2)

Linux man-pages 6.9.1                              2024-05-02                                      ioctl_pipe(2)