The following commit has been merged into the core/rcu branch of tip:
Commit-ID: 9b1ce0acb5e65e9ea1e6b322562d072f9f7d1f6e
Gitweb:
https://git.kernel.org/tip/9b1ce0acb5e65e9ea1e6b322562d072f9f7d1f6e
Author: Neeraj Upadhyay <neer...@codeaurora.org>
AuthorDate: Mon, 22 Jun 2020 23:37:03 +05:30
Committer: Paul E. McKenney <paul...@kernel.org>
CommitterDate: Mon, 24 Aug 2020 18:36:06 -07:00
rcu/tree: Remove CONFIG_PREMPT_RCU check in force_qs_rnp()
Originally, the call to rcu_preempt_blocked_readers_cgp() from
force_qs_rnp() had to be conditioned on CONFIG_PREEMPT_RCU=y, as in
commit a77da14ce9af ("rcu: Yet another fix for preemption and CPU
hotplug"). However, there is now a CONFIG_PREEMPT_RCU=n definition of
rcu_preempt_blocked_readers_cgp() that unconditionally returns zero, so
invoking it is now safe. In addition, the CONFIG_PREEMPT_RCU=n definition
of rcu_initiate_boost() simply releases the rcu_node structure's ->lock,
which is what happens when the "if" condition evaluates to false.
This commit therefore drops the IS_ENABLED(CONFIG_PREEMPT_RCU) check,
so that rcu_initiate_boost() is called only in CONFIG_PREEMPT_RCU=y
kernels when there are readers blocking the current grace period.
This does not change the behavior, but reduces code-reader confusion by
eliminating non-CONFIG_PREEMPT_RCU=y calls to rcu_initiate_boost().
Signed-off-by: Neeraj Upadhyay <neer...@codeaurora.org>
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
---
kernel/rcu/tree.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 4770d77..acc926f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2533,8 +2533,7 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rcu_state.cbovldnext |= !!rnp->cbovldmask;
if (rnp->qsmask == 0) {
- if (!IS_ENABLED(CONFIG_PREEMPT_RCU) ||
- rcu_preempt_blocked_readers_cgp(rnp)) {
+ if (rcu_preempt_blocked_readers_cgp(rnp)) {
/*
* No point in scanning bits because they
* are all zero. But we might need to
