rcu: Initialize and destroy rcu_synchronize only when necessary (7ee880b7) · Commits · 戴 / test

The __wait_rcu_gp() function unconditionally initializes and cleans up each element of rs_array[], whether used or not. This is slightly wasteful and rather confusing, so this commit skips both initialization and cleanup for duplicate callback functions. Signed-off-by:

Wei Yang <richard.weiyang@gmail.com> Signed-off-by:

Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/update.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -390,14 +390,15 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
		might_sleep();
		continue;
		}
		init_rcu_head_on_stack(&rs_array[i].head);
		init_completion(&rs_array[i].completion);
		for (j = 0; j < i; j++)
		if (crcu_array[j] == crcu_array[i])
		break;
		if (j == i)
		if (j == i) {
		init_rcu_head_on_stack(&rs_array[i].head);
		init_completion(&rs_array[i].completion);
		(crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
		}
		}

		/* Wait for all callbacks to be invoked. */
		for (i = 0; i < n; i++) {
		@@ -407,11 +408,12 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
		for (j = 0; j < i; j++)
		if (crcu_array[j] == crcu_array[i])
		break;
		if (j == i)
		if (j == i) {
		wait_for_completion(&rs_array[i].completion);
		destroy_rcu_head_on_stack(&rs_array[i].head);
		}
		}
		}
		EXPORT_SYMBOL_GPL(__wait_rcu_gp);

		#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD

Admin message