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| author |   Oleg Nesterov <oleg@redhat.com> | 2019-04-25 18:50:55 +0200 |
|---|---|---|
| committer |   Paul E. McKenney <paulmck@linux.ibm.com> | 2019-05-28 09:05:23 -0700 |
| commit | 89da3b94bb97417ca2c5b0ce3a28643819030247 (patch) | |
| tree | 3a494bdabb013141bbb60f7380b5a0f64d23872b /tools | |
| parent | locking/percpu-rwsem: Add DEFINE_PERCPU_RWSEM(), use it to initialize cgroup_threadgroup_rwsem (diff) | |
| download | linux-dev-89da3b94bb97417ca2c5b0ce3a28643819030247.tar.xz linux-dev-89da3b94bb97417ca2c5b0ce3a28643819030247.zip | |
rcu/sync: Simplify the state machine
With this patch rcu_sync has a single state variable and the transition rules
become really simple:
GP_IDLE - owned by the first rcu_sync_enter() which moves it to
GP_ENTER - owned by rcu-callback which moves it to
GP_PASSED - owned by the last rcu_sync_exit() which moves it to
GP_EXIT - and this is the only "nontrivial" state.
rcu-callback moves it back to GP_IDLE unless another enter()
comes before a GP pass.
If rcu-callback is invoked before the next rcu_sync_exit() it
must see gp_count incremented by that enter() and set GP_PASSED.
Otherwise, if the next rcu_sync_exit() wins the race, it will
move it to
GP_REPLAY - owned by rcu-callback which moves it to GP_EXIT
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
[ paulmck: While here, apply READ_ONCE() and WRITE_ONCE() to ->gp_state. ]
[ paulmck: Tweaks to make htmldocs happy. (Reported by kbuild test robot.) ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'tools')
0 files changed, 0 insertions, 0 deletions