Re: [Qemu-devel] [PATCH v2] char: restore read callback on a reattached (hotplug) chardev

[Paolo Bonzini <pbonzini@redhat.com>]

Il 11/12/2013 10:47, Gal Hammer ha scritto:
> Fix a bug that was introduced in commit 386a5a1e. A removal of a device
> set the chr handlers to NULL. However when the device is plugged back,
> its read callback is not restored so data can't be transfter from the
> host to the guest via the virtio-serial port.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1027181
> 
> V2: - do not call chr_update_read_handler on device removal.
>     - add asserts to verify chr_update_read_handler is not called
>       with an assigned fd_in_tag to prevent fd leaks.
>     - update fd and udp backends' chr_update_read_handler function
>       so it won't remove fd_in to prevent a double release.
> 
> Signed-off-by: Gal Hammer <ghammer@redhat.com>
> ---
>  qemu-char.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/qemu-char.c b/qemu-char.c
> index e00f84c..69649f0 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -213,7 +213,7 @@ void qemu_chr_add_handlers(CharDriverState *s,
>      s->chr_read = fd_read;
>      s->chr_event = fd_event;
>      s->handler_opaque = opaque;
> -    if (s->chr_update_read_handler)
> +    if (fe_open && s->chr_update_read_handler)
>          s->chr_update_read_handler(s);
>  
>      if (!s->explicit_fe_open) {
> @@ -870,6 +870,7 @@ static void fd_chr_update_read_handler(CharDriverState *chr)
>  {
>      FDCharDriver *s = chr->opaque;
>  
> +    assert(!chr->fd_in_tag);
>      remove_fd_in_watch(chr);
>      if (s->fd_in) {
>          chr->fd_in_tag = io_add_watch_poll(s->fd_in, fd_chr_read_poll,
> @@ -2228,7 +2229,7 @@ static void udp_chr_update_read_handler(CharDriverState *chr)
>  {
>      NetCharDriver *s = chr->opaque;
>  
> -    remove_fd_in_watch(chr);
> +    assert(!chr->fd_in_tag);
>      if (s->chan) {
>          chr->fd_in_tag = io_add_watch_poll(s->chan, udp_chr_read_poll,
>                                             udp_chr_read, chr);
> @@ -2510,6 +2511,17 @@ static void tcp_chr_connect(void *opaque)
>      qemu_chr_be_generic_open(chr);
>  }
>  
> +static void tcp_chr_update_read_handler(CharDriverState *chr)
> +{
> +    TCPCharDriver *s = chr->opaque;
> +
> +    assert(!chr->fd_in_tag);
> +    if (s->chan && !chr->fd_in_tag) {
> +        chr->fd_in_tag = io_add_watch_poll(s->chan, tcp_chr_read_poll,
> +                                           tcp_chr_read, chr);
> +    }
> +}
> +
>  #define IACSET(x,a,b,c) x[0] = a; x[1] = b; x[2] = c;
>  static void tcp_chr_telnet_init(int fd)
>  {
> @@ -2665,6 +2677,7 @@ static CharDriverState *qemu_chr_open_socket_fd(int fd, bool do_nodelay,
>      chr->get_msgfd = tcp_get_msgfd;
>      chr->chr_add_client = tcp_chr_add_client;
>      chr->chr_add_watch = tcp_chr_add_watch;
> +    chr->chr_update_read_handler = tcp_chr_update_read_handler;
>      /* be isn't opened until we get a connection */
>      chr->explicit_be_open = true;
>  
> 

Cc: qemu-stable@nongnu.org