diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2021-02-26 11:25:29 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-03-15 13:53:24 -0700 |
| commit | 7e937220afa3eada0d4611b31e4e3c60770e39b4 (patch) | |
| tree | 3e5f1785dbab114fc34d174e6dfd79bfc0615f6c /kernel/rcu | |
| parent | e589c7c72315f7e52ebb5cffc19615dc18d0cc50 (diff) | |
rcu: Add explicit barrier() to __rcu_read_unlock()
Because preemptible RCU's __rcu_read_unlock() is an external function,
the rough equivalent of an implicit barrier() is inserted by the compiler.
Except that there is a direct call to __rcu_read_unlock() in that same
file, and compilers are getting to the point where they might choose to
inline the fastpath of the __rcu_read_unlock() function.
This commit therefore adds an explicit barrier() to the very beginning
of __rcu_read_unlock().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 2d603771c7dc..a32494c4b6f6 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -393,8 +393,9 @@ void __rcu_read_unlock(void) { struct task_struct *t = current; + barrier(); // critical section before exit code. if (rcu_preempt_read_exit() == 0) { - barrier(); /* critical section before exit code. */ + barrier(); // critical-section exit before .s check. if (unlikely(READ_ONCE(t->rcu_read_unlock_special.s))) rcu_read_unlock_special(t); } |