From: "Paul E. McKenney" <[email protected]> Currently, each CPU discovers the beginning of a given grace period on its own time, which is again good for efficiency but bad for fast grace periods. This commit therefore uses on_each_cpu() to IPI each CPU after grace-period initialization in order to inform each CPU of the new grace period in a timely manner, but only in kernels build with CONFIG_RCU_STRICT_GRACE_PERIOD=y.
Reported-by Jann Horn <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tree.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 4353a1a..a30d6f3 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1678,6 +1678,15 @@ static void rcu_gp_torture_wait(void) } /* + * Handler for on_each_cpu() to invoke the target CPU's RCU core + * processing. + */ +static void rcu_strict_gp_boundary(void *unused) +{ + invoke_rcu_core(); +} + +/* * Initialize a new grace period. Return false if no grace period required. */ static bool rcu_gp_init(void) @@ -1805,6 +1814,10 @@ static bool rcu_gp_init(void) WRITE_ONCE(rcu_state.gp_activity, jiffies); } + // If strict, make all CPUs aware of new grace period. + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + on_each_cpu(rcu_strict_gp_boundary, NULL, 0); + return true; } -- 2.9.5
