On Sat, Feb 22, 2020 at 10:48 AM Daniel Vetter daniel.vetter@ffwll.ch wrote:
On Fri, Feb 21, 2020 at 10:36 PM Chris Wilson chris@chris-wilson.co.uk wrote:
Quoting Daniel Vetter (2020-02-21 21:02:30)
For two reasons:
- The driver core clears this already for us after we're unloaded in __device_release_driver().
Even if we abort before loading?
History notes that i915_pci_remove was called with a stale pointer on error.
So even if there's a bug we still have the problem that clearing the pci_drvdata in our drm_driver->release hook is way too late. You could already have bound a new driver to the underlying device. So if driver core doesn't clear drvdata on bind failure and we need to clear this ourselves, then this line here could actually clear the drvdata of the next driver instance bound to the pci device. Not that that's ever going to happen outside of very contrived testing.
But looking at really_probe() in base/dd.c we do clear drvdata on failure. So no idea how/why that stale drvdata came to be. Anyway that's kinda why I cc'ed Greg, so he could confirm that this is correct.
Looking at git history, this was fixed in driver core in
commit 0998d0631001288a5974afc0b2a5f568bcdecb4d Author: Hans de Goede hdegoede@redhat.com Date: Wed May 23 00:09:34 2012 +0200
device-core: Ensure drvdata = NULL when no driver is bound
I'll add that to the commit message. -Daniel