Messages in this thread Patch in this message | | | Subject | Re: [PATCH 5/5] locking/percpu-rwsem: Remove the embedded rwsem | From | Waiman Long <> | Date | Mon, 18 Nov 2019 16:52:23 -0500 |
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On 11/13/19 5:21 AM, Peter Zijlstra wrote: > @@ -130,20 +131,12 @@ static inline void percpu_rwsem_release( > bool read, unsigned long ip) > { > lock_release(&sem->dep_map, ip); > -#ifdef CONFIG_RWSEM_SPIN_ON_OWNER > - if (!read) > - atomic_long_set(&sem->rw_sem.owner, RWSEM_OWNER_UNKNOWN); > -#endif > } >
This is the only place that set RWSEM_OWNER_UNKNOWN. So you may as well remove all references to it:
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 00d6054687dd..8a418d9eeb7a 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -53,12 +53,6 @@ struct rw_semaphore { #endif }; -/* - * Setting all bits of the owner field except bit 0 will indicate - * that the rwsem is writer-owned with an unknown owner. - */ -#define RWSEM_OWNER_UNKNOWN (-2L) - /* In all implementations count != 0 means locked */ static inline int rwsem_is_locked(struct rw_semaphore *sem) { diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index eef04551eae7..622842754c73 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -660,8 +660,6 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semapho unsigned long flags; bool ret = true; - BUILD_BUG_ON(!(RWSEM_OWNER_UNKNOWN & RWSEM_NONSPINNABLE)); - if (need_resched()) { lockevent_inc(rwsem_opt_fail); return false;
Cheers, Longman
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