rcutorture: Make rcu_torture_barrier_cbs() post from corresponding CPU (50d4b629) · Commits · 戴 / test

Currently, rcu_torture_barrier_cbs() posts callbacks from whatever CPU it is running on, which means that all these kthreads might well be posting from the same CPU, which would drastically reduce the effectiveness of this test. This commit therefore uses IPIs to make the callbacks be posted from the corresponding CPU (given by local variable myid). If the IPI fails (which can happen if the target CPU is offline or does not exist at all), the callback is posted on whatever CPU is currently running. Signed-off-by:

Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/rcutorture.c

+13 −3

Original line number	Diff line number	Diff line
		@@ -2053,6 +2053,14 @@ static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
		atomic_inc(&barrier_cbs_invoked);
		}

		/* IPI handler to get callback posted on desired CPU, if online. */
		static void rcu_torture_barrier1cb(void *rcu_void)
		{
		struct rcu_head *rhp = rcu_void;

		cur_ops->call(rhp, rcu_torture_barrier_cbf);
		}

		/* kthread function to register callbacks used to test RCU barriers. */
		static int rcu_torture_barrier_cbs(void *arg)
		{
		@@ -2076,9 +2084,11 @@ static int rcu_torture_barrier_cbs(void *arg)
		* The above smp_load_acquire() ensures barrier_phase load
		* is ordered before the following ->call().
		*/
		local_irq_disable(); /* Just to test no-irq call_rcu(). */
		if (smp_call_function_single(myid, rcu_torture_barrier1cb,
		&rcu, 1)) {
		// IPI failed, so use direct call from current CPU.
		cur_ops->call(&rcu, rcu_torture_barrier_cbf);
		local_irq_enable();
		}
		if (atomic_dec_and_test(&barrier_cbs_count))
		wake_up(&barrier_wq);
		} while (!torture_must_stop());

Admin message