Re: [PATCH v13 07/19] multi-process: add qio channel function to transmit data and fds

["Marc-André Lureau" <marcandre.lureau@gmail.com>]

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Hi

On Mon, Dec 14, 2020 at 9:15 AM Jagannathan Raman <jag.raman@oracle.com>
wrote:

> From: Elena Ufimtseva <elena.ufimtseva@oracle.com>
>
> Adds QIO channel functions that transmit and receive iovs along with fds.
>
> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  include/io/channel.h | 50 +++++++++++++++++++++++++++++++++++++++++
>  io/channel.c         | 63
> +++++++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 112 insertions(+), 1 deletion(-)
>
> diff --git a/include/io/channel.h b/include/io/channel.h
> index 4d6fe45..c2d9836 100644
> --- a/include/io/channel.h
> +++ b/include/io/channel.h
> @@ -774,4 +774,54 @@ void qio_channel_set_aio_fd_handler(QIOChannel *ioc,
>                                      IOHandler *io_write,
>                                      void *opaque);
>
> +/**
> + * qio_channel_readv_full_all:
> + * @ioc: the channel object
> + * @iov: the array of memory regions to read data to
> + * @niov: the length of the @iov array
> + * @fds: an array of file handles to read
> + * @nfds: number of file handles in @fds
> + * @errp: pointer to a NULL-initialized error object
> + *
> + *
> + * Behaves like qio_channel_readvv_full but will attempt
> + * to read all data specified (file handles and memory regions).
> + * The function will wait for all requested data
> + * to be read, yielding from the current coroutine
> + * if required.
> + *
> + * Returns: 0 if all bytes were read, or -1 on error
> + */
> +
> +int qio_channel_readv_full_all(QIOChannel *ioc,
> +                                const struct iovec *iov,
> +                                size_t niov,
> +                                int **fds, size_t *nfds,
> +                                Error **errp);
> +
> +/**
> + * qio_channel_writev_full_all:
> + * @ioc: the channel object
> + * @iov: the array of memory regions to write data from
> + * @niov: the length of the @iov array
> + * @fds: an array of file handles to send
> + * @nfds: number of file handles in @fds
> + * @errp: pointer to a NULL-initialized error object
> + *
> + *
> + * Behaves like qio_channel_writev_full but will attempt
> + * to send all data passed (file handles and memory regions).
> + * The function will wait for all requested data
> + * to be written, yielding from the current coroutine
> + * if required.
> + *
> + * Returns: 0 if all bytes were written, or -1 on error
> + */
> +
> +int qio_channel_writev_full_all(QIOChannel *ioc,
> +                           const struct iovec *iov,
> +                           size_t niov,
> +                           int *fds, size_t nfds,
> +                           Error **errp);
> +
>  #endif /* QIO_CHANNEL_H */
> diff --git a/io/channel.c b/io/channel.c
> index 93d449d..13b0e7a 100644
> --- a/io/channel.c
> +++ b/io/channel.c
> @@ -152,15 +152,72 @@ int qio_channel_readv_all(QIOChannel *ioc,
>      return ret;
>  }
>
> +int qio_channel_readv_full_all(QIOChannel *ioc,
> +                                const struct iovec *iov,
> +                                size_t niov,
> +                                int **fds, size_t *nfds,
> +                                Error **errp)
> +{
> +    int ret = -1;
> +    struct iovec *local_iov = g_new(struct iovec, niov);
> +    struct iovec *local_iov_head = local_iov;
> +    unsigned int nlocal_iov = niov;
> +    int **local_fds = fds;
> +    size_t *local_nfds = nfds;
> +
> +    nlocal_iov = iov_copy(local_iov, nlocal_iov,
> +                          iov, niov,
> +                          0, iov_size(iov, niov));
> +
> +    while (nlocal_iov > 0) {
> +        ssize_t len;
> +        len = qio_channel_readv_full(ioc, local_iov, nlocal_iov,
> local_fds,
> +                                     local_nfds, errp);
> +        if (len == QIO_CHANNEL_ERR_BLOCK) {
> +            if (qemu_in_coroutine()) {
> +                qio_channel_yield(ioc, G_IO_OUT);
> +            } else {
> +                qio_channel_wait(ioc, G_IO_OUT);
> +            }
> +            continue;
> +        }
> +        if (len <= 0) {
> +            ret = len;
> +            goto cleanup;
> +        }
> +
> +        iov_discard_front(&local_iov, &nlocal_iov, len);
> +
> +        local_fds = NULL;
> +        local_nfds = 0;
> +    }
> +
> +    ret = 1;
> + cleanup:
> +    g_free(local_iov_head);
> +    return ret;
> +}
> +
>

I suggest to adapt the code so qio_channel_readv_all_eof() calls
qio_channel_readv_full_all().

You may want to split this patch in 2 parts: the read and write parts.


>  int qio_channel_writev_all(QIOChannel *ioc,
>                             const struct iovec *iov,
>                             size_t niov,
>                             Error **errp)
>  {
> +    return qio_channel_writev_full_all(ioc, iov, niov, NULL, 0, errp);
> +}
> +
> +int qio_channel_writev_full_all(QIOChannel *ioc,
> +                                const struct iovec *iov,
> +                                size_t niov,
> +                                int *fds, size_t nfds,
> +                                Error **errp)
> +{
>      int ret = -1;
>      struct iovec *local_iov = g_new(struct iovec, niov);
>      struct iovec *local_iov_head = local_iov;
>      unsigned int nlocal_iov = niov;
> +    int *local_fds = fds;
> +    size_t local_nfds = nfds;
>
>      nlocal_iov = iov_copy(local_iov, nlocal_iov,
>                            iov, niov,
> @@ -168,7 +225,8 @@ int qio_channel_writev_all(QIOChannel *ioc,
>
>      while (nlocal_iov > 0) {
>          ssize_t len;
> -        len = qio_channel_writev(ioc, local_iov, nlocal_iov, errp);
> +        len = qio_channel_writev_full(ioc, local_iov, nlocal_iov,
> local_fds,
> +                                      local_nfds, errp);
>          if (len == QIO_CHANNEL_ERR_BLOCK) {
>              if (qemu_in_coroutine()) {
>                  qio_channel_yield(ioc, G_IO_OUT);
> @@ -182,6 +240,9 @@ int qio_channel_writev_all(QIOChannel *ioc,
>          }
>
>          iov_discard_front(&local_iov, &nlocal_iov, len);
> +
> +        local_fds = NULL;
> +        local_nfds = 0;
>      }
>
>      ret = 0;
> --
> 1.8.3.1
>
>

-- 
Marc-André Lureau

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