diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-02-04 11:34:37 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-02-11 15:10:57 +0300 |
| commit | bcba67cd806800fa8e973ac49dbc7d2d8fb3e55e (patch) | |
| tree | 3d6fe168cd5bccb14aaca011a89164534b1123ef | |
| parent | 7f26482a872c36b2ee87ea95b9dcd96e3d5805df (diff) | |
| download | linux-bcba67cd806800fa8e973ac49dbc7d2d8fb3e55e.tar.xz | |
locking/rwsem: Remove RWSEM_OWNER_UNKNOWN
Remove the now unused RWSEM_OWNER_UNKNOWN hack. This hack breaks
PREEMPT_RT and getting rid of it was the entire motivation for
re-writing the percpu rwsem.
The biggest problem is that it is fundamentally incompatible with any
form of Priority Inheritance, any exclusively held lock must have a
distinct owner.
Requested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20200204092228.GP14946@hirez.programming.kicks-ass.net
| -rw-r--r-- | include/linux/rwsem.h | 6 | ||||
| -rw-r--r-- | kernel/locking/rwsem.c | 2 |
2 files changed, 0 insertions, 8 deletions
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 81c0d75d5dab..e6f437bafb23 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -659,8 +659,6 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem, unsigned long flags; bool ret = true; - BUILD_BUG_ON(!(RWSEM_OWNER_UNKNOWN & RWSEM_NONSPINNABLE)); - if (need_resched()) { lockevent_inc(rwsem_opt_fail); return false; |