Re: [Qemu-devel] [PATCH v4 20/47] ivshmem: simplify a bit the code

[Claudio Fontana <claudio.fontana@huawei.com>]

On 24.09.2015 13:37, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> Use some more explicit variables to simplify the code.
> 
> nth_eventfd variable is the current eventfd to be manipulated.

"the new_eventfd variable is the new eventfd to be manipulated".
Although after the name change it is so obvious that maybe it could be removed from the commit message?

> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  hw/misc/ivshmem.c | 28 ++++++++++++++--------------
>  1 file changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index 63bcf6c..c59d9ed 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -488,9 +488,10 @@ static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
>  {
>      IVShmemState *s = opaque;
>      int incoming_fd;
> -    int guest_max_eventfd;
> +    int new_eventfd;
>      long incoming_posn;
>      Error *err = NULL;
> +    Peer *peer;
>  
>      if (!fifo_update_and_get(s, buf, size,
>                               &incoming_posn, sizeof(incoming_posn))) {
> @@ -517,6 +518,8 @@ static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
>          }
>      }
>  
> +    peer = &s->peers[incoming_posn];
> +
>      if (incoming_fd == -1) {
>          /* if posn is positive and unseen before then this is our posn*/
>          if (incoming_posn >= 0 && s->vm_id == -1) {
> @@ -564,27 +567,24 @@ static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
>          return;
>      }
>  
> -    /* each guest has an array of eventfds, and we keep track of how many
> -     * guests for each VM */
> -    guest_max_eventfd = s->peers[incoming_posn].nb_eventfds;
> +    /* each peer has an associated array of eventfds, and we keep
> +     * track of how many eventfds received so far */
> +    /* get a new eventfd: */
> +    new_eventfd = peer->nb_eventfds++;
>  
>      /* this is an eventfd for a particular guest VM */
>      IVSHMEM_DPRINTF("eventfds[%ld][%d] = %d\n", incoming_posn,
> -                    guest_max_eventfd, incoming_fd);
> -    event_notifier_init_fd(&s->peers[incoming_posn].eventfds[guest_max_eventfd],
> -                           incoming_fd);
> -
> -    /* increment count for particular guest */
> -    s->peers[incoming_posn].nb_eventfds++;
> +                    new_eventfd, incoming_fd);
> +    event_notifier_init_fd(&peer->eventfds[new_eventfd], incoming_fd);
>  
>      if (incoming_posn == s->vm_id) {
> -        s->eventfd_chr[guest_max_eventfd] = create_eventfd_chr_device(s,
> -                   &s->peers[s->vm_id].eventfds[guest_max_eventfd],
> -                   guest_max_eventfd);
> +        s->eventfd_chr[new_eventfd] = create_eventfd_chr_device(s,
> +                   &s->peers[s->vm_id].eventfds[new_eventfd],
> +                   new_eventfd);
>      }
>  
>      if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
> -        ivshmem_add_eventfd(s, incoming_posn, guest_max_eventfd);
> +        ivshmem_add_eventfd(s, incoming_posn, new_eventfd);
>      }
>  }
>  
>