From: Paul E. McKenney Date: Mon, 13 May 2013 13:53:37 +0000 (-0700) Subject: rcu: Fix comparison sense in rcu_needs_cpu() X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=6faf72834d9d0c0dc6632604eaeffb621e87fcf9;p=openwrt%2Fstaging%2Fblogic.git rcu: Fix comparison sense in rcu_needs_cpu() Commit c0f4dfd4f (rcu: Make RCU_FAST_NO_HZ take advantage of numbered callbacks) introduced a bug that can result in excessively long grace periods. This bug reverse the senes of the "if" statement checking for lazy callbacks, so that RCU takes a lazy approach when there are in fact non-lazy callbacks. This can result in excessive boot, suspend, and resume times. This commit therefore fixes the sense of this "if" statement. Reported-by: Borislav Petkov Reported-by: Bjørn Mork Reported-by: Joerg Roedel Signed-off-by: Paul E. McKenney Tested-by: Bjørn Mork Tested-by: Joerg Roedel --- diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 170814dc418f..6d939a645da1 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1667,7 +1667,7 @@ int rcu_needs_cpu(int cpu, unsigned long *dj) rdtp->last_accelerate = jiffies; /* Request timer delay depending on laziness, and round. */ - if (rdtp->all_lazy) { + if (!rdtp->all_lazy) { *dj = round_up(rcu_idle_gp_delay + jiffies, rcu_idle_gp_delay) - jiffies; } else {