Messages in this thread Patch in this message | | | From | paulmck@kernel ... | Subject | [PATCH tip/core/rcu 09/12] rcu: IPI all CPUs at GP end for strict GPs | Date | Wed, 12 Aug 2020 15:57:29 -0700 |
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From: "Paul E. McKenney" <paulmck@kernel.org>
Currently, each CPU discovers the end of a given grace period on its own time, which is again good for efficiency but bad for fast grace periods, given that it is things like kfree() within the RCU callbacks that will cause trouble for pointers leaked from RCU read-side critical sections. This commit therefore uses on_each_cpu() to IPI each CPU after grace-period cleanup in order to inform each CPU of the end of the old grace period in a timely manner, but only in kernels build with CONFIG_RCU_STRICT_GRACE_PERIOD=y.
Reported-by Jann Horn <jannh@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- kernel/rcu/tree.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a30d6f3..dd7af40 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2034,6 +2034,10 @@ static void rcu_gp_cleanup(void) rcu_state.gp_flags & RCU_GP_FLAG_INIT); } raw_spin_unlock_irq_rcu_node(rnp); + + // If strict, make all CPUs aware of the end of the old grace period. + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + on_each_cpu(rcu_strict_gp_boundary, NULL, 0); } /* -- 2.9.5
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