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authorJoel Fernandes (Google) <joel@joelfernandes.org>2019-08-15 22:59:14 -0400
committerPaul E. McKenney <paulmck@kernel.org>2019-10-30 08:34:35 -0700
commit05ef9e9eb3dade21413680f41eb0170778e8ae2b (patch)
tree6e57e0d53beeec1aeda061fe7e53b05ad18e9d37 /kernel/rcu
parent5a6446626d7e062b47a5cc1cf27d5060e60bb0d9 (diff)
rcu: Ensure that ->rcu_urgent_qs is set before resched IPI
The RCU-specific resched_cpu() function sends a resched IPI to the specified CPU, which can be used to force the tick on for a given nohz_full CPU. This is needed when this nohz_full CPU is looping in the kernel while blocking the current grace period. However, for the tick to actually be forced on in all cases, that CPU's rcu_data structure's ->rcu_urgent_qs flag must be set beforehand. This commit therefore causes rcu_implicit_dynticks_qs() to set this flag prior to invoking resched_cpu() on a holdout nohz_full CPU. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 81105141b6a8..0d83b1944e19 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1073,6 +1073,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
if (tick_nohz_full_cpu(rdp->cpu) &&
time_after(jiffies,
READ_ONCE(rdp->last_fqs_resched) + jtsq * 3)) {
+ WRITE_ONCE(*ruqp, true);
resched_cpu(rdp->cpu);
WRITE_ONCE(rdp->last_fqs_resched, jiffies);
}