Re: [Qemu-devel] [PATCH v2 25/42] ivshmem: Disentangle ivshmem_read()

[Marc-André Lureau]

On Mon, Mar 7, 2016 at 8:25 PM, Markus Armbruster <address@hidden> wrote:
> Signed-off-by: Markus Armbruster <address@hidden>
> ---

Reviewed-by: Marc-André Lureau <address@hidden>


>  hw/misc/ivshmem.c | 172 
> +++++++++++++++++++++++++++---------------------------
>  1 file changed, 87 insertions(+), 85 deletions(-)
>
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index 5d33be4..e568263 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -564,115 +564,117 @@ static void setup_interrupt(IVShmemState *s, int 
> vector)
>      }
>  }
>
> -static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
> +static void process_msg_shmem(IVShmemState *s, int fd)
>  {
> -    IVShmemState *s = opaque;
> -    int incoming_fd;
> -    int new_eventfd;
> -    int64_t incoming_posn;
>      Error *err = NULL;
> -    Peer *peer;
> +    void *ptr;
>
> -    if (!fifo_update_and_get_i64(s, buf, size, &incoming_posn)) {
> +    if (memory_region_is_mapped(&s->ivshmem)) {
> +        error_report("shm already initialized");
> +        close(fd);
>          return;
>      }
>
> -    incoming_fd = qemu_chr_fe_get_msgfd(s->server_chr);
> -    IVSHMEM_DPRINTF("posn is %" PRId64 ", fd is %d\n",
> -                    incoming_posn, incoming_fd);
> -
> -    if (incoming_posn < -1 || incoming_posn > IVSHMEM_MAX_PEERS) {
> -        error_report("server sent invalid message %" PRId64,
> -                     incoming_posn);
> -        if (incoming_fd != -1) {
> -            close(incoming_fd);
> -        }
> -        return;
> -    }
> -
> -    if (incoming_posn >= s->nb_peers) {
> -        resize_peers(s, incoming_posn + 1);
> -    }
> -
> -    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) {
> -            /* receive our posn */
> -            s->vm_id = incoming_posn;
> -        } else {
> -            /* otherwise an fd == -1 means an existing peer has gone away */
> -            IVSHMEM_DPRINTF("posn %" PRId64 " has gone away\n", 
> incoming_posn);
> -            close_peer_eventfds(s, incoming_posn);
> -        }
> +    if (check_shm_size(s, fd, &err) == -1) {
> +        error_report_err(err);
> +        close(fd);
>          return;
>      }
>
> -    /* if the position is -1, then it's shared memory region fd */
> -    if (incoming_posn == -1) {
> -        void * map_ptr;
> -
> -        if (memory_region_is_mapped(&s->ivshmem)) {
> -            error_report("shm already initialized");
> -            close(incoming_fd);
> -            return;
> -        }
> -
> -        if (check_shm_size(s, incoming_fd, &err) == -1) {
> -            error_report_err(err);
> -            close(incoming_fd);
> -            return;
> -        }
> -
> -        /* mmap the region and map into the BAR2 */
> -        map_ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED,
> -                                                            incoming_fd, 0);
> -        if (map_ptr == MAP_FAILED) {
> -            error_report("Failed to mmap shared memory %s", strerror(errno));
> -            close(incoming_fd);
> -            return;
> -        }
> -        memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s),
> -                                   "ivshmem.bar2", s->ivshmem_size, map_ptr);
> -        qemu_set_ram_fd(s->ivshmem.ram_addr, incoming_fd);
> -        vmstate_register_ram(&s->ivshmem, DEVICE(s));
> -
> -        IVSHMEM_DPRINTF("guest h/w addr = %p, size = %" PRIu64 "\n",
> -                        map_ptr, s->ivshmem_size);
> -
> -        memory_region_add_subregion(&s->bar, 0, &s->ivshmem);
> -
> +    /* mmap the region and map into the BAR2 */
> +    ptr = mmap(0, s->ivshmem_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 
> 0);
> +    if (ptr == MAP_FAILED) {
> +        error_report("Failed to mmap shared memory %s", strerror(errno));
> +        close(fd);
>          return;
>      }
> -
> -    /* each peer has an associated array of eventfds, and we keep
> -     * track of how many eventfds received so far */
> -    /* get a new eventfd: */
> +    memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s),
> +                               "ivshmem.bar2", s->ivshmem_size, ptr);
> +    qemu_set_ram_fd(s->ivshmem.ram_addr, fd);
> +    vmstate_register_ram(&s->ivshmem, DEVICE(s));
> +    memory_region_add_subregion(&s->bar, 0, &s->ivshmem);
> +}
> +
> +static void process_msg_disconnect(IVShmemState *s, uint16_t posn)
> +{
> +    IVSHMEM_DPRINTF("posn %d has gone away\n", posn);
> +    close_peer_eventfds(s, posn);
> +}
> +
> +static void process_msg_connect(IVShmemState *s, uint16_t posn, int fd)
> +{
> +    Peer *peer = &s->peers[posn];
> +    int vector;
> +
> +    /*
> +     * The N-th connect message for this peer comes with the file
> +     * descriptor for vector N-1.  Count messages to find the vector.
> +     */
>      if (peer->nb_eventfds >= s->vectors) {
>          error_report("Too many eventfd received, device has %d vectors",
>                       s->vectors);
> -        close(incoming_fd);
> +        close(fd);
>          return;
>      }
> +    vector = peer->nb_eventfds++;
>
> -    new_eventfd = peer->nb_eventfds++;
> +    IVSHMEM_DPRINTF("eventfds[%d][%d] = %d\n", posn, vector, fd);
> +    event_notifier_init_fd(&peer->eventfds[vector], fd);
> +    fcntl_setfl(fd, O_NONBLOCK); /* msix/irqfd poll non block */
>
> -    /* this is an eventfd for a particular peer VM */
> -    IVSHMEM_DPRINTF("eventfds[%" PRId64 "][%d] = %d\n", incoming_posn,
> -                    new_eventfd, incoming_fd);
> -    event_notifier_init_fd(&peer->eventfds[new_eventfd], incoming_fd);
> -    fcntl_setfl(incoming_fd, O_NONBLOCK); /* msix/irqfd poll non block */
> -
> -    if (incoming_posn == s->vm_id) {
> -        setup_interrupt(s, new_eventfd);
> +    if (posn == s->vm_id) {
> +        setup_interrupt(s, vector);
>      }
>
>      if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
> -        ivshmem_add_eventfd(s, incoming_posn, new_eventfd);
> +        ivshmem_add_eventfd(s, posn, vector);
>      }
>  }
>
> +static void process_msg(IVShmemState *s, int64_t msg, int fd)
> +{
> +    IVSHMEM_DPRINTF("posn is %" PRId64 ", fd is %d\n", msg, fd);
> +
> +    if (msg < -1 || msg > IVSHMEM_MAX_PEERS) {
> +        error_report("server sent invalid message %" PRId64, msg);
> +        close(fd);
> +        return;
> +    }
> +
> +    if (msg == -1) {
> +        process_msg_shmem(s, fd);
> +        return;
> +    }
> +
> +    if (msg >= s->nb_peers) {
> +        resize_peers(s, msg + 1);
> +    }
> +
> +    if (fd >= 0) {
> +        process_msg_connect(s, msg, fd);
> +    } else if (s->vm_id == -1) {
> +        s->vm_id = msg;
> +    } else {
> +        process_msg_disconnect(s, msg);
> +    }
> +}
> +
> +static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
> +{
> +    IVShmemState *s = opaque;
> +    int fd;
> +    int64_t msg;
> +
> +    if (!fifo_update_and_get_i64(s, buf, size, &msg)) {
> +        return;
> +    }
> +
> +    fd = qemu_chr_fe_get_msgfd(s->server_chr);
> +    IVSHMEM_DPRINTF("posn is %" PRId64 ", fd is %d\n", msg, fd);
> +
> +    process_msg(s, msg, fd);
> +}
> +
>  static void ivshmem_check_version(void *opaque, const uint8_t * buf, int 
> size)
>  {
>      IVShmemState *s = opaque;
> --
> 2.4.3
>
>



-- 
Marc-André Lureau