Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index befc932..477b4eb 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -1,23 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
* Copyright IBM Corporation, 2008
*
- * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
*
* For detailed explanation of Read-Copy Update mechanism see -
* Documentation/RCU
@@ -46,69 +33,27 @@
};
/* Definition for rcupdate control block. */
-static struct rcu_ctrlblk rcu_sched_ctrlblk = {
- .donetail = &rcu_sched_ctrlblk.rcucblist,
- .curtail = &rcu_sched_ctrlblk.rcucblist,
+static struct rcu_ctrlblk rcu_ctrlblk = {
+ .donetail = &rcu_ctrlblk.rcucblist,
+ .curtail = &rcu_ctrlblk.rcucblist,
};
-static struct rcu_ctrlblk rcu_bh_ctrlblk = {
- .donetail = &rcu_bh_ctrlblk.rcucblist,
- .curtail = &rcu_bh_ctrlblk.rcucblist,
-};
-
-void rcu_barrier_bh(void)
+void rcu_barrier(void)
{
- wait_rcu_gp(call_rcu_bh);
+ wait_rcu_gp(call_rcu);
}
-EXPORT_SYMBOL(rcu_barrier_bh);
+EXPORT_SYMBOL(rcu_barrier);
-void rcu_barrier_sched(void)
+/* Record an rcu quiescent state. */
+void rcu_qs(void)
{
- wait_rcu_gp(call_rcu_sched);
-}
-EXPORT_SYMBOL(rcu_barrier_sched);
+ unsigned long flags;
-/*
- * Helper function for rcu_sched_qs() and rcu_bh_qs().
- * Also irqs are disabled to avoid confusion due to interrupt handlers
- * invoking call_rcu().
- */
-static int rcu_qsctr_help(struct rcu_ctrlblk *rcp)
-{
- if (rcp->donetail != rcp->curtail) {
- rcp->donetail = rcp->curtail;
- return 1;
+ local_irq_save(flags);
+ if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {
+ rcu_ctrlblk.donetail = rcu_ctrlblk.curtail;
+ raise_softirq_irqoff(RCU_SOFTIRQ);
}
-
- return 0;
-}
-
-/*
- * Record an rcu quiescent state. And an rcu_bh quiescent state while we
- * are at it, given that any rcu quiescent state is also an rcu_bh
- * quiescent state. Use "+" instead of "||" to defeat short circuiting.
- */
-void rcu_sched_qs(void)
-{
- unsigned long flags;
-
- local_irq_save(flags);
- if (rcu_qsctr_help(&rcu_sched_ctrlblk) +
- rcu_qsctr_help(&rcu_bh_ctrlblk))
- raise_softirq(RCU_SOFTIRQ);
- local_irq_restore(flags);
-}
-
-/*
- * Record an rcu_bh quiescent state.
- */
-void rcu_bh_qs(void)
-{
- unsigned long flags;
-
- local_irq_save(flags);
- if (rcu_qsctr_help(&rcu_bh_ctrlblk))
- raise_softirq(RCU_SOFTIRQ);
local_irq_restore(flags);
}
@@ -118,36 +63,35 @@
* be called from hardirq context. It is normally called from the
* scheduling-clock interrupt.
*/
-void rcu_check_callbacks(int user)
+void rcu_sched_clock_irq(int user)
{
- if (user)
- rcu_sched_qs();
- if (user || !in_softirq())
- rcu_bh_qs();
+ if (user) {
+ rcu_qs();
+ } else if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {
+ set_tsk_need_resched(current);
+ set_preempt_need_resched();
+ }
}
-/*
- * Invoke the RCU callbacks on the specified rcu_ctrlkblk structure
- * whose grace period has elapsed.
- */
-static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
+/* Invoke the RCU callbacks whose grace period has elapsed. */
+static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
{
struct rcu_head *next, *list;
unsigned long flags;
/* Move the ready-to-invoke callbacks to a local list. */
local_irq_save(flags);
- if (rcp->donetail == &rcp->rcucblist) {
+ if (rcu_ctrlblk.donetail == &rcu_ctrlblk.rcucblist) {
/* No callbacks ready, so just leave. */
local_irq_restore(flags);
return;
}
- list = rcp->rcucblist;
- rcp->rcucblist = *rcp->donetail;
- *rcp->donetail = NULL;
- if (rcp->curtail == rcp->donetail)
- rcp->curtail = &rcp->rcucblist;
- rcp->donetail = &rcp->rcucblist;
+ list = rcu_ctrlblk.rcucblist;
+ rcu_ctrlblk.rcucblist = *rcu_ctrlblk.donetail;
+ *rcu_ctrlblk.donetail = NULL;
+ if (rcu_ctrlblk.curtail == rcu_ctrlblk.donetail)
+ rcu_ctrlblk.curtail = &rcu_ctrlblk.rcucblist;
+ rcu_ctrlblk.donetail = &rcu_ctrlblk.rcucblist;
local_irq_restore(flags);
/* Invoke the callbacks on the local list. */
@@ -162,37 +106,31 @@
}
}
-static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
-{
- __rcu_process_callbacks(&rcu_sched_ctrlblk);
- __rcu_process_callbacks(&rcu_bh_ctrlblk);
-}
-
/*
* Wait for a grace period to elapse. But it is illegal to invoke
- * synchronize_sched() from within an RCU read-side critical section.
- * Therefore, any legal call to synchronize_sched() is a quiescent
- * state, and so on a UP system, synchronize_sched() need do nothing.
- * Ditto for synchronize_rcu_bh(). (But Lai Jiangshan points out the
- * benefits of doing might_sleep() to reduce latency.)
+ * synchronize_rcu() from within an RCU read-side critical section.
+ * Therefore, any legal call to synchronize_rcu() is a quiescent
+ * state, and so on a UP system, synchronize_rcu() need do nothing.
+ * (But Lai Jiangshan points out the benefits of doing might_sleep()
+ * to reduce latency.)
*
* Cool, huh? (Due to Josh Triplett.)
*/
-void synchronize_sched(void)
+void synchronize_rcu(void)
{
RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
lock_is_held(&rcu_lock_map) ||
lock_is_held(&rcu_sched_lock_map),
- "Illegal synchronize_sched() in RCU read-side critical section");
+ "Illegal synchronize_rcu() in RCU read-side critical section");
}
-EXPORT_SYMBOL_GPL(synchronize_sched);
+EXPORT_SYMBOL_GPL(synchronize_rcu);
/*
- * Helper function for call_rcu() and call_rcu_bh().
+ * Post an RCU callback to be invoked after the end of an RCU grace
+ * period. But since we have but one CPU, that would be after any
+ * quiescent state.
*/
-static void __call_rcu(struct rcu_head *head,
- rcu_callback_t func,
- struct rcu_ctrlblk *rcp)
+void call_rcu(struct rcu_head *head, rcu_callback_t func)
{
unsigned long flags;
@@ -201,39 +139,20 @@
head->next = NULL;
local_irq_save(flags);
- *rcp->curtail = head;
- rcp->curtail = &head->next;
+ *rcu_ctrlblk.curtail = head;
+ rcu_ctrlblk.curtail = &head->next;
local_irq_restore(flags);
if (unlikely(is_idle_task(current))) {
- /* force scheduling for rcu_sched_qs() */
+ /* force scheduling for rcu_qs() */
resched_cpu(0);
}
}
-
-/*
- * Post an RCU callback to be invoked after the end of an RCU-sched grace
- * period. But since we have but one CPU, that would be after any
- * quiescent state.
- */
-void call_rcu_sched(struct rcu_head *head, rcu_callback_t func)
-{
- __call_rcu(head, func, &rcu_sched_ctrlblk);
-}
-EXPORT_SYMBOL_GPL(call_rcu_sched);
-
-/*
- * Post an RCU bottom-half callback to be invoked after any subsequent
- * quiescent state.
- */
-void call_rcu_bh(struct rcu_head *head, rcu_callback_t func)
-{
- __call_rcu(head, func, &rcu_bh_ctrlblk);
-}
-EXPORT_SYMBOL_GPL(call_rcu_bh);
+EXPORT_SYMBOL_GPL(call_rcu);
void __init rcu_init(void)
{
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
rcu_early_boot_tests();
+ srcu_init();
}