diff options
| -rw-r--r-- | kernel/rcu/tree.c | 6 | ||||
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 9 |
2 files changed, 7 insertions, 8 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 9ce682242e99..3bee58fc23b1 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3280,12 +3280,6 @@ static inline int rcu_blocking_is_gp(void) * to have executed a full memory barrier during the execution of * synchronize_sched() -- even if CPU A and CPU B are the same CPU (but * again only if the system has more than one CPU). - * - * This primitive provides the guarantees made by the (now removed) - * synchronize_kernel() API. In contrast, synchronize_rcu() only - * guarantees that rcu_read_lock() sections will have completed. - * In "classic RCU", these two guarantees happen to be one and - * the same, but can differ in realtime RCU implementations. */ void synchronize_sched(void) { diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index a421753e8e9c..3b432fa4c45b 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -664,8 +664,13 @@ EXPORT_SYMBOL_GPL(call_rcu); * synchronize_rcu() was waiting. RCU read-side critical sections are * delimited by rcu_read_lock() and rcu_read_unlock(), and may be nested. * - * See the description of synchronize_sched() for more detailed information - * on memory ordering guarantees. + * See the description of synchronize_sched() for more detailed + * information on memory-ordering guarantees. However, please note + * that -only- the memory-ordering guarantees apply. For example, + * synchronize_rcu() is -not- guaranteed to wait on things like code + * protected by preempt_disable(), instead, synchronize_rcu() is -only- + * guaranteed to wait on RCU read-side critical sections, that is, sections + * of code protected by rcu_read_lock(). */ void synchronize_rcu(void) { |