Commit-ID: fcc878e4dfb70128a73857c609d70570629b0d9e
Gitweb: https://git.kernel.org/tip/fcc878e4dfb70128a73857c609d70570629b0d9e
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Thu, 28 Jun 2018 07:39:59 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 30 Aug 2018 16:02:36 -0700
rcu: Remove now-unused ->b.exp_need_qs field from the rcu_special union
The ->b.exp_need_qs field is now set only to false, so this commit
removes it. The job this field used to do is now done by the rcu_data
structure's ->deferred_qs field, which is a consequence of a better
split between task-based (the rcu_node structure's ->exp_tasks field) and
CPU-based (the aforementioned rcu_data structure's ->deferred_qs field)
tracking of quiescent states for RCU-preempt expedited grace periods.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 6 +-----
kernel/rcu/tree_plugin.h | 13 ++++---------
2 files changed, 5 insertions(+), 14 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 977cb57d7bc9..004ca21f7e80 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -571,12 +571,8 @@ union rcu_special {
struct {
u8 blocked;
u8 need_qs;
- u8 exp_need_qs;
-
- /* Otherwise the compiler can store garbage here: */
- u8 pad;
} b; /* Bits. */
- u32 s; /* Set of bits. */
+ u16 s; /* Set of bits. */
};
enum perf_event_task_context {
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 24c209676d20..527a52792dce 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -284,13 +284,10 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
* no need to check for a subsequent expedited GP. (Though we are
* still in a quiescent state in any case.)
*/
- if (blkd_state & RCU_EXP_BLKD &&
- t->rcu_read_unlock_special.b.exp_need_qs) {
- t->rcu_read_unlock_special.b.exp_need_qs = false;
+ if (blkd_state & RCU_EXP_BLKD && rdp->deferred_qs)
rcu_report_exp_rdp(rdp->rsp, rdp, true);
- } else {
- WARN_ON_ONCE(t->rcu_read_unlock_special.b.exp_need_qs);
- }
+ else
+ WARN_ON_ONCE(rdp->deferred_qs);
}
/*
@@ -509,9 +506,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
* tasks are handled when removing the task from the
* blocked-tasks list below.
*/
- if (special.b.exp_need_qs || rdp->deferred_qs) {
- t->rcu_read_unlock_special.b.exp_need_qs = false;
- rdp->deferred_qs = false;
+ if (rdp->deferred_qs) {
rcu_report_exp_rdp(rcu_state_p, rdp, true);
if (!t->rcu_read_unlock_special.s) {
local_irq_restore(flags);
|