linux-toradex.git/kernel/locking/percpu-rwsem.c, branch v4.4-rc6

locking/percpu-rwsem: Clean up the lockdep annotations in percpu_down_read()

2015-10-06T18:25:40+00:00

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 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

locking/percpu-rwsem: Fix the comments outdated by rcu_sync

2015-10-06T18:25:36+00:00

Update the comments broken by the previous change.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

locking/percpu-rwsem: Make use of the rcu_sync infrastructure

2015-10-06T18:25:31+00:00

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 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

locking/percpu-rwsem: Make percpu_free_rwsem() after kzalloc() safe

2015-10-06T18:25:26+00:00

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 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

locking/percpu-rwsem: Export symbols for locktorture

2015-10-06T18:24:51+00:00

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 
Reviewed-by: Josh Triplett

percpu-rwsem: introduce percpu_down_read_trylock()

2015-08-15T11:52:10+00:00

Add percpu_down_read_trylock(), it will have the user soon.

Signed-off-by: Oleg Nesterov

locking: Move the percpu-rwsem code to kernel/locking/

2013-11-06T08:24:22+00:00

Suggested-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-52bjmtty46we26hbfd9sc9iy@git.kernel.org
Signed-off-by: Ingo Molnar