drm: safely free connectors from connector_iter
In commit 613051da Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Wed Dec 14 00:08:06 2016 +0100 drm: locking&new iterators for connector_list we've went to extreme lengths to make sure connector iterations works in any context, without introducing any additional locking context. This worked, except for a small fumble in the implementation: When we actually race with a concurrent connector unplug event, and our temporary connector reference turns out to be the final one, then everything breaks: We call the connector release function from whatever context we happen to be in, which can be an irq/atomic context. And connector freeing grabs all kinds of locks and stuff. Fix this by creating a specially safe put function for connetor_iter, which (in this rare case) punts the cleanup to a worker. Reported-by: NBen Widawsky <ben@bwidawsk.net> Cc: Ben Widawsky <ben@bwidawsk.net> Fixes: 613051da ("drm: locking&new iterators for connector_list") Cc: Dave Airlie <airlied@gmail.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Sean Paul <seanpaul@chromium.org> Cc: <stable@vger.kernel.org> # v4.11+ Reviewed-by: NDave Airlie <airlied@gmail.com> Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20171204204818.24745-1-daniel.vetter@ffwll.ch
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