From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 05/19] rcu: Remove now-unused ->b.exp_need_qs field from the rcu_special union
Date: Wed, 29 Aug 2018 15:20:33 -0700 [thread overview]
Message-ID: <20180829222047.319-5-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180829222021.GA29944@linux.vnet.ibm.com>
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@linux.vnet.ibm.com>
---
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);
--
2.17.1
next prev parent reply other threads:[~2018-08-29 22:22 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 22:20 [PATCH tip/core/rcu 0/19] RCU flavor-consolidation changes for v4.20/v5.0 Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 01/19] rcu: Refactor rcu_{nmi,irq}_{enter,exit}() Paul E. McKenney
2018-08-30 18:10 ` Steven Rostedt
2018-08-30 23:02 ` Paul E. McKenney
2018-08-31 2:25 ` Byungchul Park
2018-08-29 22:20 ` [PATCH tip/core/rcu 02/19] rcu: Defer reporting RCU-preempt quiescent states when disabled Paul E. McKenney
2018-10-29 11:24 ` Ran Rozenstein
2018-10-29 14:27 ` Paul E. McKenney
2018-10-30 3:44 ` Joel Fernandes
2018-10-30 12:58 ` Paul E. McKenney
2018-10-30 22:21 ` Joel Fernandes
2018-10-31 18:22 ` Paul E. McKenney
2018-11-02 19:43 ` Paul E. McKenney
2018-11-26 13:55 ` Ran Rozenstein
2018-11-26 19:00 ` Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 03/19] rcutorture: Test extended "rcu" read-side critical sections Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 04/19] rcu: Allow processing deferred QSes for exiting RCU-preempt readers Paul E. McKenney
2018-08-29 22:20 ` Paul E. McKenney [this message]
2018-08-29 22:20 ` [PATCH tip/core/rcu 06/19] rcu: Add warning to detect half-interrupts Paul E. McKenney
2019-03-11 13:39 ` Joel Fernandes
2019-03-11 22:29 ` Paul E. McKenney
2019-03-12 15:05 ` Joel Fernandes
2019-03-12 15:20 ` Paul E. McKenney
2019-03-13 15:09 ` Joel Fernandes
2019-03-13 15:27 ` Steven Rostedt
2019-03-13 15:51 ` Paul E. McKenney
2019-03-13 16:51 ` Steven Rostedt
2019-03-13 18:07 ` Paul E. McKenney
2019-03-14 12:31 ` Joel Fernandes
2019-03-14 13:36 ` Steven Rostedt
2019-03-14 13:37 ` Steven Rostedt
2019-03-14 21:27 ` Joel Fernandes
2019-03-15 7:31 ` Byungchul Park
2019-03-15 7:44 ` Byungchul Park
2019-03-15 13:46 ` Joel Fernandes
2018-08-29 22:20 ` [PATCH tip/core/rcu 07/19] rcu: Apply RCU-bh QSes to RCU-sched and RCU-preempt when safe Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 08/19] rcu: Report expedited grace periods at context-switch time Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 09/19] rcu: Define RCU-bh update API in terms of RCU Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 10/19] rcu: Update comments and help text for no more RCU-bh updaters Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 11/19] rcu: Drop "wake" parameter from rcu_report_exp_rdp() Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 12/19] rcu: Fix typo in rcu_get_gp_kthreads_prio() header comment Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 13/19] rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 14/19] rcu: Express Tiny RCU updates in terms of RCU rather than RCU-sched Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 15/19] rcu: Remove RCU_STATE_INITIALIZER() Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 16/19] rcu: Eliminate rcu_state structure's ->call field Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 17/19] rcu: Remove rcu_state structure's ->rda field Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 18/19] rcu: Remove rcu_state_p pointer to default rcu_state structure Paul E. McKenney
2018-08-29 22:20 ` [PATCH tip/core/rcu 19/19] rcu: Remove rcu_data_p pointer to default rcu_data structure Paul E. McKenney
2018-08-29 22:22 ` [PATCH tip/core/rcu 0/19] RCU flavor-consolidation changes for v4.20/v5.0 Paul E. McKenney
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