io_uring_prep_msg_ring_fd(3) — Linux manual page

io_uring_prep_msg_ring(3)    liburing Manual   io_uring_prep_msg_ring(3)

NAME

       io_uring_prep_msg_ring_fd - send a direct descriptor to another
       ring

SYNOPSIS

       #include <liburing.h>

       void io_uring_prep_msg_ring_fd(struct io_uring_sqe *sqe,
                               int fd,
                               int source_fd,
                               int target_fd,
                               __u64 data,
                               unsigned int flags);

       void io_uring_prep_msg_ring_fd_alloc(struct io_uring_sqe *sqe,
                               int fd,
                               int source_fd,
                               __u64 data,
                               unsigned int flags);

DESCRIPTION

       io_uring_prep_msg_ring_fd(3) prepares an SQE to send a direct
       file descriptor to another ring. The submission queue entry sqe
       is setup to use the file descriptor fd, which must identify a
       target io_uring context, to send the locally registered file
       descriptor with value source_fd to the destination ring into
       index target_fd and passing data as the user data in the target
       CQE with the request modifier flags set by flags.  Currently
       there are no valid flag modifiers, this field must contain 0.

       io_uring_prep_msg_ring_fd_alloc(3) is similar to
       io_uring_prep_msg_ring_fd(3), but doesn't specify a target index
       for the direct descriptor. Instead, this index is allocated in
       the target ring and returned in the CQE res field.

RETURN VALUE

       None

ERRORS

       These are the errors that are reported in the CQE res field.

       -ENOMEM
              The kernel was unable to allocate memory for the request.

       -EINVAL
              One of the fields set in the SQE was invalid.

       -EINVAL
              Target ring is identical to the source ring.

       -EBADFD
              The descriptor passed in fd does not refer to an io_uring
              file descriptor, or the ring is in a disabled state.

       -EOVERFLOW
              The kernel was unable to fill a CQE on the target ring.
              This can happen if the target CQ ring is in an overflow
              state and the kernel wasn't able to allocate memory for a
              new CQE entry.

       -ENFILE
              The direct descriptor table in the target ring was full,
              no new descriptors could be successfully allocated.

COLOPHON

       This page is part of the liburing (A library for io_uring)
       project.  Information about the project can be found at 
       ⟨https://github.com/axboe/liburing⟩.  If you have a bug report for
       this manual page, send it to io-uring@vger.kernel.org.  This page
       was obtained from the project's upstream Git repository
       ⟨https://github.com/axboe/liburing⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-03.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

liburing-2.4                  Mar 16, 2023     io_uring_prep_msg_ring(3)

Pages that refer to this page: io_uring_prep_msg_ring_fd(3), io_uring_prep_msg_ring_fd_alloc(3)

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