diff options
| -rw-r--r-- | Documentation/RCU/Design/Requirements/Requirements.rst | 7 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 9 |
2 files changed, 10 insertions, 6 deletions
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst index b5cdbba3ec2e..4d886e7c7a95 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -2787,6 +2787,13 @@ which avoids the read-side memory barriers, at least for architectures that apply noinstr to kernel entry/exit code (or that build with ``CONFIG_TASKS_TRACE_RCU_NO_MB=y``. +Now that the implementation is based on SRCU-fast, a call +to synchronize_rcu_tasks_trace() implies at least one call to +synchronize_rcu(), that is, every Tasks Trace RCU grace period contains +at least one plain vanilla RCU grace period. Should there ever +be a synchronize_rcu_tasks_trace_expedited(), this guarantee would +*not* necessarily apply to this hypothetical API member. + The tasks-trace-RCU API is also reasonably compact, consisting of rcu_read_lock_trace(), rcu_read_unlock_trace(), rcu_read_lock_trace_held(), call_rcu_tasks_trace(), diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 04f3f86a4145..18a85c30fd4f 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -208,12 +208,9 @@ static inline void exit_tasks_rcu_finish(void) { } /** * rcu_trace_implies_rcu_gp - does an RCU Tasks Trace grace period imply an RCU grace period? * - * As an accident of implementation, an RCU Tasks Trace grace period also - * acts as an RCU grace period. However, this could change at any time. - * Code relying on this accident must call this function to verify that - * this accident is still happening. - * - * You have been warned! + * Now that RCU Tasks Trace is implemented in terms of SRCU-fast, a + * call to synchronize_rcu_tasks_trace() is guaranteed to imply at least + * one call to synchronize_rcu(). */ static inline bool rcu_trace_implies_rcu_gp(void) { return true; } |