io_uring_prep_poll_add(3)	 liburing Manual       io_uring_prep_poll_add(3)

NAME
     io_uring_prep_poll_add - prepare a poll request

SYNOPSIS
     #include <poll.h>
     #include <liburing.h>

     void io_uring_prep_poll_add(struct io_uring_sqe *sqe,
				 int fd,
				 unsigned poll_mask);

     void io_uring_prep_poll_multishot(struct io_uring_sqe *sqe,
				       int fd,
				       unsigned poll_mask);

DESCRIPTION
     The io_uring_prep_poll_add(3) function prepares a poll request. The submis-
     sion queue entry sqe is setup to use the file descriptor fd that should get
     polled, with the events desired specified in the poll_mask argument.

     The  default  behavior  is	 a  single-shot poll request. When the specified
     event has triggered, a completion CQE is posted and no more events will  be
     generated	by  the	 poll  request.	 io_uring_prep_poll_multishot(3) behaves
     identically in terms of events, but it persists  across  notifications  and
     will  repeatedly post notifications for the same registration. A CQE posted
     from a multishot poll request will have IORING_CQE_F_MORE set  in	the  CQE
     flags  member,  indicating	 that the application should expect more comple-
     tions from this request. If the multishot poll request gets  terminated  or
     experiences  an  error,  this flag will not be set in the CQE. If this hap-
     pens, the application should not expect further CQEs from the original  re-
     quest and must reissue a new one if it still wishes to get notifications on
     this file descriptor.


RETURN VALUE
     None

ERRORS
     The CQE res field will contain the result of the operation, which is a bit-
     mask  of  the  events  notified. See the poll(2) man page for details. Note
     that where synchronous system calls will return -1 on failure and set errno
     to the actual error value, io_uring never uses errno.  Instead  it	 returns
     the negated errno directly in the CQE res field.

SEE ALSO
     io_uring_get_sqe(3), io_uring_submit(3), poll(2), epoll_ctl(3)

liburing-2.2			 March 12, 2022	       io_uring_prep_poll_add(3)