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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <2d6c1ef40f3678ab47a4d14fb5dadaa486bfcda6.1300712809.git.amit.shah@redhat.com>
	(Amit Shah's message of "Mon, 21 Mar 2011 18:39:22 +0530")
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	<cover.1300712809.git.amit.shah@redhat.com>
	<2d6c1ef40f3678ab47a4d14fb5dadaa486bfcda6.1300712809.git.amit.shah@redhat.com>
Date: Wed, 23 Mar 2011 14:32:44 +0100
Message-ID: <m3mxkmrmgz.fsf@neno.mitica>
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Subject: [Qemu-devel] Re: [PATCH 7/7] char: Prevent multiple devices opening
	same chardev
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To: Amit Shah <amit.shah@redhat.com>
Cc: qemu list <qemu-devel@nongnu.org>

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.