https://bugs.kde.org/show_bug.cgi?id=500951
--- Comment #6 from Sanfod Rockowitz <rockow...@minsoft.com> --- I have made extensive extensive changes to libddcutil in branch 2.2.1-dev to detect API usage errors and diagnose display lock deadlocks. A key problem is that calling ddca_redetect_displays() while display watch is active can produce invalid states. Prior to release 2.2.0, display change detection just informed the client by callback that the display configuration had changed, leaving it to the client to call ddca_redetect_displays() which tells libddcutil to discard everything it knows about connected displays. As of release 2.2.0, display change detection updates libddcuti's internal tables and informs the client by callback what has changed. The client should not need to call ddca_redetect_displays(). A key check is preventing ddca_redetect_displays() from executing with callback threads are active. This can lead to corrupt data structures. Callback functions run in their own thread and libddcutil does not block until the callback completes - otherwise an errant callback function could hang display watch detection. Unfortunately, I don't see a way to distinguish using the glib API between callbacks that are still executing, and which should bock ddca_redetect_displays(), and ones that have actually died. So at best what happens is that an error message is written to the system log warning the ddca_redetect_displays() appears to be called when callback threads are executing. But again, all this convoluted and imperfect logic can be avoided by avoiding use of ddca_redetect_displays() If deadlocks persist, please run with the following settings in configuration file ddcutilrc: options: --ts --tid options: --ts --trace api --trcfile display_lock.c options: --trace-to-syslog-only options: --trcfunc add_open_display_for_current_thread --trcfunc remove_open_display_for_current_thread options: --trcfunc ddc_close_all_displays_for_current_thread options: --trcfunc unlock_all_displays_for_current_thread options: --trcfunc dw_execute_callback_func Output to the system log will be voluminous. Error messages in the system log may immediately indicate the problem. Otherwise leave it to me to examine the output. Unfortunately, I am traveling with only my laptop, so I am unable to test all these changes by attaching and detaching monitors. I also expect to be unavailable for the next several days. But I wanted to give people the opportunity to test with them. -- You are receiving this mail because: You are watching all bug changes.
