Commit c7dcf810 authored Jun 12, 2020 by Paul E. McKenney

rcu-tasks: Fix synchronize_rcu_tasks_trace() header comment

The synchronize_rcu_tasks_trace() header comment incorrectly claims that
any number of things delimit RCU Tasks Trace read-side critical sections,
when in fact only rcu_read_lock_trace() and rcu_read_unlock_trace() do so.
This commit therefore fixes this comment, and, while in the area, fixes
a typo in the rcu_read_lock_trace() header comment.

Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

parent e13ef442

include/linux/rcupdate_trace.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -36,8 +36,8 @@ void rcu_read_unlock_trace_special(struct task_struct *t, int nesting);
		/**
		* rcu_read_lock_trace - mark beginning of RCU-trace read-side critical section
		*
		* When synchronize_rcu_trace() is invoked by one task, then that task
		* is guaranteed to block until all other tasks exit their read-side
		* When synchronize_rcu_tasks_trace() is invoked by one task, then that
		* task is guaranteed to block until all other tasks exit their read-side
		* critical sections. Similarly, if call_rcu_trace() is invoked on one
		* task while other tasks are within RCU read-side critical sections,
		* invocation of the corresponding RCU callback is deferred until after

kernel/rcu/tasks.h

+4 −5

Original line number	Diff line number	Diff line
		@@ -1118,11 +1118,10 @@ EXPORT_SYMBOL_GPL(call_rcu_tasks_trace);
		* synchronize_rcu_tasks_trace - wait for a trace rcu-tasks grace period
		*
		* Control will return to the caller some time after a trace rcu-tasks
		* grace period has elapsed, in other words after all currently
		* executing rcu-tasks read-side critical sections have elapsed. These
		* read-side critical sections are delimited by calls to schedule(),
		* cond_resched_tasks_rcu_qs(), userspace execution, and (in theory,
		* anyway) cond_resched().
		* grace period has elapsed, in other words after all currently executing
		* rcu-tasks read-side critical sections have elapsed. These read-side
		* critical sections are delimited by calls to rcu_read_lock_trace()
		* and rcu_read_unlock_trace().
		*
		* This is a very specialized primitive, intended only for a few uses in
		* tracing and other situations requiring manipulation of function preambles