summaryrefslogtreecommitdiffstats
path: root/kernel/rcu
diff options
context:
space:
mode:
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-04-11 16:41:20 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-05-15 10:29:24 -0700
commit5fe0a56298e674358ff2740a6288bf21509d895d (patch)
tree61a2926d9340b746ff535c954d193e0ae9c6448c /kernel/rcu
parentc91a8675b9cc697c725b6d97fcc7f157f4a989d0 (diff)
downloadlinux-5fe0a56298e674358ff2740a6288bf21509d895d.tar.bz2
rcu: Make rcu_gp_kthread() check for early-boot activity
The rcu_gp_kthread() function immediately sleeps waiting to be notified of the need for a new grace period, which currently works because there are a number of code sequences that will provide the needed wakeup later. However, some of these code sequences need to acquire the root rcu_node structure's ->lock, and contention on that lock has started manifesting. This commit therefore makes rcu_gp_kthread() check for early-boot activity when it starts up, omitting the initial sleep in that case. Reported-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Nicholas Piggin <npiggin@gmail.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 79fb99951a0c..497f139056c7 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2192,6 +2192,12 @@ static int __noreturn rcu_gp_kthread(void *arg)
struct rcu_state *rsp = arg;
struct rcu_node *rnp = rcu_get_root(rsp);
+ /* Check for early-boot work. */
+ raw_spin_lock_irq_rcu_node(rnp);
+ if (need_any_future_gp(rnp))
+ WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
+ raw_spin_unlock_irq_rcu_node(rnp);
+
rcu_bind_gp_kthread();
for (;;) {