rcu: Fix outdated rcu_scheduler_active comment (0d95092c) · Commits · 戴 / test

The comment header for rcu_scheduler_active states that it is used to optimize synchronize_sched() at early boot. This is incorrect. The synchronize_sched() function instead checks the number of online CPUs. This commit therefore replaces the comment's synchronize_sched() with synchronize_rcu(), which really does use rcu_scheduler_active for this purpose. Reported-by:

Lihao Liang <lihao.liang@gmail.com> Signed-off-by:

Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/tree.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -130,7 +130,7 @@ int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */
		* The rcu_scheduler_active variable transitions from zero to one just
		* before the first task is spawned. So when this variable is zero, RCU
		* can assume that there is but one task, allowing RCU to (for example)
		* optimize synchronize_sched() to a simple barrier(). When this variable
		* optimize synchronize_rcu() to a simple barrier(). When this variable
		* is one, RCU must actually do all the hard work required to detect real
		* grace periods. This variable is also used to suppress boot-time false
		* positives from lockdep-RCU error checking.

Admin message