Commit 0a89e5a4 authored Oct 15, 2018 by Paul E. McKenney

rcu: Trace end of grace period before end of grace period

Currently, rcu_gp_cleanup() traces the end of the old grace period after
the old grace period has officially ended. This might make intuitive
sense, but it also makes for confusing event-trace output because the
"end" trace displays not the old but instead the new grace-period number.
This commit therefore traces the end of an old grace period just before
that grace period officially ends.

Reported-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

parent 2320bda2

kernel/rcu/tree.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -2035,9 +2035,9 @@ static void rcu_gp_cleanup(void)
		rnp = rcu_get_root();
		raw_spin_lock_irq_rcu_node(rnp); /* GP before ->gp_seq update. */

		/* Declare grace period done. */
		rcu_seq_end(&rcu_state.gp_seq);
		/* Declare grace period done, trace first to use old GP number. */
		trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("end"));
		rcu_seq_end(&rcu_state.gp_seq);
		rcu_state.gp_state = RCU_GP_IDLE;
		/* Check for GP requests since above loop. */
		rdp = this_cpu_ptr(&rcu_data);

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