mainlining shenanigans
12a280c728
For very subtle mistakes with topology refs, it can be rather difficult to trace them down with the debugging info that we already have. I had one such issue recently while trying to implement suspend/resume reprobing for MST, and ended up coming up with this. Inspired by Chris Wilson's wakeref tracking for i915, this adds a very similar feature to the DP MST helpers, which allows for partial tracking of topology refs for both ports and branch devices. This is a lot less advanced then wakeref tracking: we merely keep a count of all of the spots where a topology ref has been grabbed or dropped, then dump out that history in chronological order when a port or branch device's topology refcount reaches 0. So far, I've found this incredibly useful for debugging topology refcount errors. Since this has the potential to be somewhat slow and loud, we add an expert kernel config option to enable or disable this feature, CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. Changes since v1: * Don't forget to destroy topology_ref_history_lock Changes since v4: * Correct order of kref_put()/topology_ref_history_unlock - we can't unlock the history after kref_put() since the memory might have been freed by that point * Don't print message on allocation error failures, the kernel already does this for us Changes since v5: * Get rid of some leftover usages of %px * Remove a leftover empty return; statement 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.vetter@ffwll.ch> Reviewed-by: Sean Paul <sean@poorly.run> Signed-off-by: Lyude Paul <lyude@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20191022023641.8026-15-lyude@redhat.com |
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| certs | ||
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.