[Qemu-devel] Re: [PATCH 7/7] char: Prevent multiple devices opening same chardev

[Juan Quintela <quintela@redhat.com>]

Amit Shah <amit.shah@redhat.com> wrote:
> Prevent:
>
> -chardev socket,path=/tmp/foo,server,nowait,id=c0 \
> -device virtserialport,chardev=c0,id=vs0 \
> -device virtserialport,chardev=c0,id=vs1
>
> Reported-by: Mike Cao <bcao@redhat.com>
> Signed-off-by: Amit Shah <amit.shah@redhat.com>

> @@ -197,6 +197,10 @@ void qemu_chr_add_handlers(CharDriverState *s,
>                             IOEventHandler *fd_event,
>                             void *opaque)
>  {
> +    if (!opaque) {
> +        /* chr driver being released. */
> +        s->assigned = 0;
> +    }
>      s->chr_can_read = fd_can_read;
>      s->chr_read = fd_read;
>      s->chr_event = fd_event;

I preffer to decide that a handler is empty when fd_can_read/fd_read and
fd_event are all NULL, and don't take into account the opaque handler.

This covers the case where opaque is NULL because state is implicit on
the other functions.

Later, Juan.