[PATCH 2/6] exa: increase/rework safety checks in Prepare/FinishAccess.

[Michel Dänzer]

On Mon, 2009-03-02 at 21:33 +0100, Maarten Maathuis wrote:
> 
> +    /* Check if we're dealing SRC == DST or similar. */
> +    if (pPixmap->devPrivate.ptr != NULL) {
> +       int i;
> +       for (i = 0; i < 6; i++)
> +           if (pExaScr->prepare_access[i] == pPixmap)
> +               break;

Despite your comments, I don't understand how your changes are treating
the src == dst case specially.


> +	/* Someone is messing with us, so we assert. */
> +	if (i == 6 || i == index)
> +	    assert(pPixmap->devPrivate.ptr == NULL);

If you need to abort the X server, please only use FatalError(), not
assert(). The X server currently doesn't catch SIGABRT, so the only
trace of an assertion failure would be in the X server stderr output.

I'm still not sure it's a good idea to sprinkle FatalErrors all over the
place though. These sanity checks may be nice for developer/debugging
builds to catch problems early, but for end-user builds we should try to
continue whenever reasonably possible.

In particular, AFAICT the above assertion would fail if some code path
were to call PrepareAccess twice for the same pixmap and index. That
would probably not be intended, but it's far from an unrecoverable
problem.

 
-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer