Re: Deadlock between fbcon and fb_defio?

On Mon, May 10, 2010 at 12:49 AM, Bruno Prémont
[off-list ref] wrote:

Fix crash if we are the first framebuffer loaded as in that case fbcon
wants to flush framebuffer at the end of fb registration, before we
have setup fb_defio.

Bruno,

Please help me understand, how does this scenario occur? I'm
interpreting what you've written above to mean that fbcon is accessing
the framebuffer before you've called defio_init()? Is that correct?

The typical defio use sequence is: defio_init(),
register_framebuffer() and the typical remove sequence is in the
reverse order unregister_framebuffer(), defio_cleanup(). So, I don't
see how fbcon is accessing the framebuffer either before
register_framebuffer() completes (at which point defio init is already
done) or after unregister_framebuffer() completes.

Thanks,
jaya