diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2019-10-30 20:30:41 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-02-11 13:10:56 +0100 |
| commit | 7f26482a872c36b2ee87ea95b9dcd96e3d5805df (patch) | |
| tree | 0a0e843a50333cc34780860e3378ecae2c5a52bf /kernel/locking/rwsem.h | |
| parent | locking/percpu-rwsem: Extract __percpu_down_read_trylock() (diff) | |
| download | linux-7f26482a872c36b2ee87ea95b9dcd96e3d5805df.tar.xz linux-7f26482a872c36b2ee87ea95b9dcd96e3d5805df.zip | |
locking/percpu-rwsem: Remove the embedded rwsem
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
Diffstat (limited to 'kernel/locking/rwsem.h')
| -rw-r--r-- | kernel/locking/rwsem.h | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h index d0d33a59622d..e69de29bb2d1 100644 --- a/kernel/locking/rwsem.h +++ b/kernel/locking/rwsem.h @@ -1,12 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ - -#ifndef __INTERNAL_RWSEM_H -#define __INTERNAL_RWSEM_H -#include <linux/rwsem.h> - -extern void __down_read(struct rw_semaphore *sem); -extern void __up_read(struct rw_semaphore *sem); -extern void __down_write(struct rw_semaphore *sem); -extern void __up_write(struct rw_semaphore *sem); - -#endif /* __INTERNAL_RWSEM_H */ |