samples: enhance hung_task detector test with read-write semaphore support

2025-07-20T02:08:26+00:00

Extend the hung_task detector test module to include read-write semaphore support alongside existing mutex and semaphore tests. This module now creates additional debugfs files under /hung_task, namely 'rw_semaphore_read' and 'rw_semaphore_write', in addition to 'mutex' and 'semaphore'. Reading these files with multiple processes triggers a prolonged sleep (256 seconds) while holding the respective lock, enabling hung_task detector testing for various locking mechanisms. This change builds on the extensible hung_task_tests module, adding read-write semaphore functionality to improve test coverage for kernel locking primitives. The implementation ensures proper lock handling and includes checks to prevent redundant data reads. Usage is: > cd /sys/kernel/debug/hung_task > cat mutex & cat mutex # Test mutex blocking > cat semaphore & cat semaphore # Test semaphore blocking > cat rw_semaphore_write \ & cat rw_semaphore_read # Test rwsem blocking > cat rw_semaphore_write \ & cat rw_semaphore_write # Test rwsem blocking Update the Kconfig description to reflect the addition of read-write semaphore debugfs files. Link: https://lkml.kernel.org/r/20250627072924.36567-4-lance.yang@linux.dev Signed-off-by: Zi Li Suggested-by: Masami Hiramatsu (Google) Cc: Anna Schumaker Cc: Boqun Feng Cc: Ingo Molnar Cc: Joel Granados Cc: John Stultz Cc: Kent Overstreet Cc: Mingzhe Yang Cc: Peter Zijlstra Cc: Sergey Senozhatsky Cc: Steven Rostedt Cc: Tomasz Figa Cc: Waiman Long Cc: Will Deacon Cc: Yongliang Gao Signed-off-by: Andrew Morton

samples: extend hung_task detector test with semaphore support

2025-05-12T00:54:08+00:00

Extend the existing hung_task detector test module to support multiple lock types, including mutex and semaphore, with room for future additions (e.g., spinlock, etc.). This module creates dummy files under /hung_task, such as 'mutex' and 'semaphore'. The read process on any of these files will sleep for enough long time (256 seconds) while holding the respective lock. As a result, the second process will wait on the lock for a prolonged duration and be detected by the hung_task detector. This change unifies the previous mutex-only sample into a single, extensible hung_task_tests module, reducing code duplication and improving maintainability. Usage is: > cd /sys/kernel/debug/hung_task > cat mutex & cat mutex # Test mutex blocking > cat semaphore & cat semaphore # Test semaphore blocking Update the Kconfig description to reflect multiple debugfs files support. Link: https://lkml.kernel.org/r/20250414145945.84916-4-ioworker0@gmail.com Signed-off-by: Lance Yang Signed-off-by: Zi Li Suggested-by: Masami Hiramatsu (Google) Acked-by: Masami Hiramatsu (Google) Cc: Anna Schumaker Cc: Boqun Feng Cc: Ingo Molnar Cc: Joel Granados Cc: John Stultz Cc: Kent Overstreet Cc: Mingzhe Yang Cc: Peter Zijlstra Cc: Sergey Senozhatsky Cc: Steven Rostedt Cc: Tomasz Figa Cc: Waiman Long Cc: Will Deacon Cc: Yongliang Gao Signed-off-by: Andrew Morton

kernel/linux.git/samples/hung_task/hung_task_tests.c, branch v6.18.21

samples: enhance hung_task detector test with read-write semaphore support

samples: extend hung_task detector test with semaphore support