[Spice-devel] [spice v10 10/27] server: Make the RedDrawable refcount thread-safe

[Christophe Fergeau]

On Thu, Mar 03, 2016 at 12:22:39PM -0500, Frediano Ziglio wrote:
> 
> No, Qemu must provide a thread safe release_resource.
> Two reasons:
> - release_resource is called from RedWorker which is a different
>   thread than Qemu or other users (it's just created inside spice-server);
> - I looked at Qemu code and there is a clear comment on this ;-) .

This is not how I understood this code when I looked at it, my
understanding was that it's fine that the resource release comes from a
different thread, but that it's expected to always come from the same
RedWorker thread (I assume for a given QXL device). I did not read it as
"this code is reentrant and can be called from any thread"

Looking at it again, the ring modification code in
interface_release_resource in hw/display/qxl.c do not look like
something that is thread-safe.

Christophe
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