[Bug 76582] igt/drv_module_reload causes call trace

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=76582

--- Comment #5 from David Herrmann <dh.herrmann at gmail.com> ---
I am confused by the bisect. The commit in questions just delays a free() so my
first guess was some i915 code checks for "dev->primary != NULL" and then does
a deregistration, while it should rather check for "dev->primary->kdev !=
NULL". On the other hand, no-one should check for that at all and just expect
them to be there during ->unload().

But then again, looking at the backtrace, we're currently in the i915
->unload() path, so the code modified by the commit hasn't even be called, yet.
Furthermore, the warning happens _deep_ down the i2c chain (unregistering
i2c-devices on top of i2c-adapters).

A few things that bug me:
 * this code is 1/2 a year old, why does this warning show up only _now_?
 * the bisected commit breaks module re-loading, but that was already fixed
 * the code in question hasn't even been called, yet

My suspicion is that you mixed up two different calltraces. Your comment "Same
as https://bugs.freedesktop.org/show_bug.cgi?id=71208#c5" is definitely wrong.
The stack-traces in that bug are on the devices created by DRM, unlike this
trace which is in the i2c layer.

Can you please bisect again _starting_ at least after this:

  commit a3483353ca4e6dbeef2ed62ebed01af109b5b27a
  Author: David Herrmann <dh.herrmann at gmail.com>
  Date:   Wed Nov 13 11:42:26 2013 +0100

      drm: check for !kdev in drm_unplug_minor()

And please verify the stack-traces contain "i2cdev_detach_adapter".

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