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7f26482a87
The filesystem freezer uses percpu-rwsem in a way that is effectively write_non_owner() and achieves this with a few horrible hacks that rely on the rwsem (!percpu) implementation. When PREEMPT_RT replaces the rwsem implementation with a PI aware variant this comes apart. Remove the embedded rwsem and implement it using a waitqueue and an atomic_t. - make readers_block an atomic, and use it, with the waitqueue for a blocking test-and-set write-side. - have the read-side wait for the 'lock' state to clear. Have the waiters use FIFO queueing and mark them (reader/writer) with a new WQ_FLAG. Use a custom wake_function to wake either a single writer or all readers until a writer. 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/20200204092403.GB14879@hirez.programming.kicks-ass.net |
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| .. | ||
| lock_events_list.h | ||
| lock_events.c | ||
| lock_events.h | ||
| lockdep_internals.h | ||
| lockdep_proc.c | ||
| lockdep_states.h | ||
| lockdep.c | ||
| locktorture.c | ||
| Makefile | ||
| mcs_spinlock.h | ||
| mutex-debug.c | ||
| mutex-debug.h | ||
| mutex.c | ||
| mutex.h | ||
| osq_lock.c | ||
| percpu-rwsem.c | ||
| qrwlock.c | ||
| qspinlock_paravirt.h | ||
| qspinlock_stat.h | ||
| qspinlock.c | ||
| rtmutex_common.h | ||
| rtmutex-debug.c | ||
| rtmutex-debug.h | ||
| rtmutex.c | ||
| rtmutex.h | ||
| rwsem.c | ||
| rwsem.h | ||
| semaphore.c | ||
| spinlock_debug.c | ||
| spinlock.c | ||
| test-ww_mutex.c | ||