[Intel-gfx] [PATCH 2/2] drm/i915: Don't BUG_ON in i915_gem_obj_offset

[Dave Airlie]

On 25 June 2014 11:30, Ben Widawsky <ben at bwidawsk.net> wrote:
> On Wed, Jun 18, 2014 at 12:04:46AM +0200, Daniel Vetter wrote:
>> On Tue, Jun 17, 2014 at 10:34:38PM +0200, Daniel Vetter wrote:
>> > A WARN_ON is perfectly fine.
>> >
>> > The BUG in here seems to be the cause behind hard-hangs when I cat the
>> > i915_gem_pageflip debugfs file (which calls this from an irq
>> > spinlock). But only while running a full igt run after a while. I
>> > still need to root cause the underlying issue.
>> >
>> > I'll also start reject patches which add new BUG_ON but don't come
>> > with a really good justification for it. The general rule really
>> > should be to just WARN and hope the driver survives for long enough.
>> >
>> > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>>
>> Both patches merged, this one improved per Chris' suggestions on irc.
>> -Daniel
>>
>
> Hey, here's an idea. How about we root cause bugs instead of making
> blanket statements about the validity of real assertions? If the callers
> of ggtt_offset are calling it on unbound objects, it's a violation of
> the design. And in the other cases, it's a real bug.
>
> I'd NAK this patch if it wasn't already merged, and my NAK meant
> something.
>

Its kinda hard to debug an assert if it takes the whole box down, and you
never see the assert printed anywhere. Any why should the whole
kernel die because the GPU driver stuffed up.

Maybe you confused this with userspace.

Dave.