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Lyude Paul 7cb12d4831 drm/dp_mst: Destroy MSTBs asynchronously
When reprobing an MST topology during resume, we have to account for the
fact that while we were suspended it's possible that mstbs may have been
removed from any ports in the topology. Since iterating downwards in the
topology requires that we hold &mgr->lock, destroying MSTBs from this
context would result in attempting to lock &mgr->lock a second time and
deadlocking.

So, fix this by first moving destruction of MSTBs into
destroy_connector_work, then rename destroy_connector_work and friends
to reflect that they now destroy both ports and mstbs.

Note that even though this means that MSTBs will still be accessible for
a short period of time between their removal from the topology and
delayed destruction, we are still protected against referencing a MSTB
with a refcount of 0 since we use kref_get_unless_zero() in most places.

Changes since v1:
* s/destroy_connector_list/destroy_port_list/
  s/connector_destroy_lock/delayed_destroy_lock/
  s/connector_destroy_work/delayed_destroy_work/
  s/drm_dp_finish_destroy_branch_device/drm_dp_delayed_destroy_mstb/
  s/drm_dp_finish_destroy_port/drm_dp_delayed_destroy_port/
  - danvet
* Use two loops in drm_dp_delayed_destroy_work() - danvet
* Better explain why we need to do this - danvet
* Use cancel_work_sync() instead of flush_work() - flush_work() doesn't
  account for work requeing

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191022023641.8026-2-lyude@redhat.com
2019-10-24 14:21:55 -04:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-10-20 06:31:14 -04:00
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Documentation Linux 5.4-rc4 2019-10-23 12:10:05 +02:00
drivers drm/dp_mst: Destroy MSTBs asynchronously 2019-10-24 14:21:55 -04:00
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include drm/dp_mst: Destroy MSTBs asynchronously 2019-10-24 14:21:55 -04:00
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Makefile Linux 5.4-rc4 2019-10-20 15:56:22 -04:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.