Messages in this thread | | | From | Sebastian Andrzej Siewior <> | Subject | [PATCH 0/2] locking: Provide {rwlock|spin}_is_contended on PREEMPT_RT | Date | Mon, 6 Sep 2021 16:30:02 +0200 |
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The lkp bot reported that rt_rwlock_is_contended() is not used so I looked closer.
#1 wires up rwlock_is_contended() with rt_rwlock_is_contended() as it was probably intended. As noted in the patch description, a writer will always see true based on the current implementation. This could be solved by looking at the waiters of the rtmutex underneath as done in #2 for spin_lock (which is missing). The helper is not exported and would be also needed for rwsem_is_contended() because it is using the same rw_base_is_contended() implementation.
Maybe it is not worth the trouble given that on PREEMPT_RT the rwlock/ spinlock is preemptible so it might be just best to return false and wait for the scheduler to do its magic.
Sebastian
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