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* locking/percpu-rwsem: Clean up the lockdep annotations in percpu_down_read()Oleg Nesterov2015-10-061-5/+5
| | | | | | | | | | | | | Based on Peter Zijlstra's earlier patch. Change percpu_down_read() to use __down_read(), this way we can do rwsem_acquire_read() unconditionally at the start to make this code more symmetric and clean. Originally-From: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* locking/percpu-rwsem: Fix the comments outdated by rcu_syncOleg Nesterov2015-10-061-39/+11
| | | | | | | | Update the comments broken by the previous change. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* locking/percpu-rwsem: Make use of the rcu_sync infrastructureOleg Nesterov2015-10-061-11/+7
| | | | | | | | | | | | | | | | | | Currently down_write/up_write calls synchronize_sched_expedited() twice, which is evil. Change this code to rely on rcu-sync primitives. This avoids the _expedited "big hammer", and this can be faster in the contended case or even in the case when a single thread does down_write/up_write in a loop. Of course, a single down_write() will take more time, but otoh it will be much more friendly to the whole system. To simplify the review this patch doesn't update the comments, fixed by the next change. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* locking/percpu-rwsem: Make percpu_free_rwsem() after kzalloc() safeOleg Nesterov2015-10-061-0/+7
| | | | | | | | | | | | | | This is the temporary ugly hack which will be reverted later. We only need it to ensure that the next patch will not break "change sb_writers to use percpu_rw_semaphore" patches routed via the VFS tree. The alloc_super()->destroy_super() error path assumes that it is safe to call percpu_free_rwsem() after kzalloc() without percpu_init_rwsem(), so let's not disappoint it. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* locking/percpu-rwsem: Export symbols for locktorturePaul E. McKenney2015-10-061-0/+5
| | | | | | | | | This commit exports percpu_down_read(), percpu_down_write(), __percpu_init_rwsem(), percpu_up_read(), and percpu_up_write() to allow locktorture to test them when built as a module. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* percpu-rwsem: introduce percpu_down_read_trylock()Oleg Nesterov2015-08-151-0/+13
| | | | | | Add percpu_down_read_trylock(), it will have the user soon. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
* locking: Move the percpu-rwsem code to kernel/locking/Peter Zijlstra2013-11-061-0/+165
Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-52bjmtty46we26hbfd9sc9iy@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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