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-rw-r--r--kernel/rcu/rcu.h19
-rw-r--r--kernel/rcu/rcu_segcblist.c17
-rw-r--r--kernel/rcu/rcu_segcblist.h17
-rw-r--r--kernel/rcu/rcuperf.c27
-rw-r--r--kernel/rcu/rcutorture.c59
-rw-r--r--kernel/rcu/srcutiny.c17
-rw-r--r--kernel/rcu/srcutree.c72
-rw-r--r--kernel/rcu/sync.c15
-rw-r--r--kernel/rcu/tiny.c19
-rw-r--r--kernel/rcu/tree.c52
-rw-r--r--kernel/rcu/tree.h27
-rw-r--r--kernel/rcu/tree_exp.h19
-rw-r--r--kernel/rcu/tree_plugin.h41
-rw-r--r--kernel/rcu/update.c17
14 files changed, 118 insertions, 300 deletions
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 75787186bd4f..acee72c0b24b 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -1,23 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Read-Copy Update definitions shared among RCU implementations.
*
- * 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, 2011
*
- * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
*/
#ifndef __LINUX_RCU_H
@@ -30,7 +17,7 @@
#define RCU_TRACE(stmt)
#endif /* #else #ifdef CONFIG_RCU_TRACE */
-/* Offset to allow for unmatched rcu_irq_{enter,exit}(). */
+/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
#define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1)
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 5aff271adf1e..9bd5f6023c21 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -1,23 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* RCU segmented callback lists, function definitions
*
- * 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, 2017
*
- * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
*/
#include <linux/types.h>
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 948470cef385..71b64648464e 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -1,23 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
/*
* RCU segmented callback lists, internal-to-rcu header file
*
- * 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, 2017
*
- * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
*/
#include <linux/rcu_segcblist.h>
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index b459da70b4fc..c29761152874 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -1,23 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Read-Copy Update module-based performance-test facility
*
- * 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 (C) IBM Corporation, 2015
*
- * Authors: Paul E. McKenney <paulmck@us.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
*/
#define pr_fmt(fmt) fmt
@@ -54,7 +41,7 @@
#include "rcu.h"
MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
#define PERF_FLAG "-perf:"
#define PERFOUT_STRING(s) \
@@ -83,13 +70,19 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
* Various other use cases may of course be specified.
*/
+#ifdef MODULE
+# define RCUPERF_SHUTDOWN 0
+#else
+# define RCUPERF_SHUTDOWN 1
+#endif
+
torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, nwriters, -1, "Number of RCU updater threads");
-torture_param(bool, shutdown, !IS_ENABLED(MODULE),
+torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
"Shutdown at end of performance tests.");
torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index f6e85faa4ff4..f14d1b18a74f 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1,23 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Read-Copy Update module-based torture test facility
*
- * 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 (C) IBM Corporation, 2005, 2006
*
- * Authors: Paul E. McKenney <paulmck@us.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
* Josh Triplett <josh@joshtriplett.org>
*
* See also: Documentation/RCU/torture.txt
@@ -61,7 +48,7 @@
#include "rcu.h"
MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
/* Bits for ->extendables field, extendables param, and related definitions. */
@@ -1630,21 +1617,34 @@ static bool rcu_fwd_emergency_stop;
#define MIN_FWD_CB_LAUNDERS 3 /* This many CB invocations to count. */
#define MIN_FWD_CBS_LAUNDERED 100 /* Number of counted CBs. */
#define FWD_CBS_HIST_DIV 10 /* Histogram buckets/second. */
-static long n_launders_hist[2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV)];
+struct rcu_launder_hist {
+ long n_launders;
+ unsigned long launder_gp_seq;
+};
+#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
+static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
+static unsigned long rcu_launder_gp_seq_start;
static void rcu_torture_fwd_cb_hist(void)
{
+ unsigned long gps;
+ unsigned long gps_old;
int i;
int j;
for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
- if (n_launders_hist[i] > 0)
+ if (n_launders_hist[i].n_launders > 0)
break;
pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
__func__, jiffies - rcu_fwd_startat);
- for (j = 0; j <= i; j++)
- pr_cont(" %ds/%d: %ld",
- j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j]);
+ gps_old = rcu_launder_gp_seq_start;
+ for (j = 0; j <= i; j++) {
+ gps = n_launders_hist[j].launder_gp_seq;
+ pr_cont(" %ds/%d: %ld:%ld",
+ j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
+ rcutorture_seq_diff(gps, gps_old));
+ gps_old = gps;
+ }
pr_cont("\n");
}
@@ -1666,7 +1666,8 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
if (i >= ARRAY_SIZE(n_launders_hist))
i = ARRAY_SIZE(n_launders_hist) - 1;
- n_launders_hist[i]++;
+ n_launders_hist[i].n_launders++;
+ n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
spin_unlock_irqrestore(&rcu_fwd_lock, flags);
}
@@ -1786,9 +1787,10 @@ static void rcu_torture_fwd_prog_cr(void)
n_max_cbs = 0;
n_max_gps = 0;
for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
- n_launders_hist[i] = 0;
+ n_launders_hist[i].n_launders = 0;
cver = READ_ONCE(rcu_torture_current_version);
gps = cur_ops->get_gp_seq();
+ rcu_launder_gp_seq_start = gps;
while (time_before(jiffies, stopat) &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
rfcp = READ_ONCE(rcu_fwd_cb_head);
@@ -2228,6 +2230,14 @@ static void rcu_test_debug_objects(void)
#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
}
+static void rcutorture_sync(void)
+{
+ static unsigned long n;
+
+ if (cur_ops->sync && !(++n & 0xfff))
+ cur_ops->sync();
+}
+
static int __init
rcu_torture_init(void)
{
@@ -2389,7 +2399,8 @@ rcu_torture_init(void)
firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
if (firsterr)
goto unwind;
- firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval);
+ firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
+ rcutorture_sync);
if (firsterr)
goto unwind;
firsterr = rcu_torture_stall_init();
diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
index 32dfd6522548..5d4a39a6505a 100644
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -1,24 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Sleepable Read-Copy Update mechanism for mutual exclusion,
* tiny version for non-preemptible single-CPU use.
*
- * 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 (C) IBM Corporation, 2017
*
- * Author: Paul McKenney <paulmck@us.ibm.com>
+ * Author: Paul McKenney <paulmck@linux.ibm.com>
*/
#include <linux/export.h>
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 3600d88d8956..a60b8ba9e1ac 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -1,24 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Sleepable Read-Copy Update mechanism for mutual exclusion.
*
- * 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 (C) IBM Corporation, 2006
* Copyright (C) Fujitsu, 2012
*
- * Author: Paul McKenney <paulmck@us.ibm.com>
+ * Author: Paul McKenney <paulmck@linux.ibm.com>
* Lai Jiangshan <laijs@cn.fujitsu.com>
*
* For detailed explanation of Read-Copy Update mechanism see -
@@ -58,6 +45,7 @@ static bool __read_mostly srcu_init_done;
static void srcu_invoke_callbacks(struct work_struct *work);
static void srcu_reschedule(struct srcu_struct *ssp, unsigned long delay);
static void process_srcu(struct work_struct *work);
+static void srcu_delay_timer(struct timer_list *t);
/* Wrappers for lock acquisition and release, see raw_spin_lock_rcu_node(). */
#define spin_lock_rcu_node(p) \
@@ -156,7 +144,8 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
snp->grphi = cpu;
}
sdp->cpu = cpu;
- INIT_DELAYED_WORK(&sdp->work, srcu_invoke_callbacks);
+ INIT_WORK(&sdp->work, srcu_invoke_callbacks);
+ timer_setup(&sdp->delay_work, srcu_delay_timer, 0);
sdp->ssp = ssp;
sdp->grpmask = 1 << (cpu - sdp->mynode->grplo);
if (is_static)
@@ -386,13 +375,19 @@ void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced)
} else {
flush_delayed_work(&ssp->work);
}
- for_each_possible_cpu(cpu)
+ for_each_possible_cpu(cpu) {
+ struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu);
+
if (quiesced) {
- if (WARN_ON(delayed_work_pending(&per_cpu_ptr(ssp->sda, cpu)->work)))
+ if (WARN_ON(timer_pending(&sdp->delay_work)))
+ return; /* Just leak it! */
+ if (WARN_ON(work_pending(&sdp->work)))
return; /* Just leak it! */
} else {
- flush_delayed_work(&per_cpu_ptr(ssp->sda, cpu)->work);
+ del_timer_sync(&sdp->delay_work);
+ flush_work(&sdp->work);
}
+ }
if (WARN_ON(rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) != SRCU_STATE_IDLE) ||
WARN_ON(srcu_readers_active(ssp))) {
pr_info("%s: Active srcu_struct %p state: %d\n",
@@ -463,39 +458,23 @@ static void srcu_gp_start(struct srcu_struct *ssp)
WARN_ON_ONCE(state != SRCU_STATE_SCAN1);
}
-/*
- * Track online CPUs to guide callback workqueue placement.
- */
-DEFINE_PER_CPU(bool, srcu_online);
-void srcu_online_cpu(unsigned int cpu)
+static void srcu_delay_timer(struct timer_list *t)
{
- WRITE_ONCE(per_cpu(srcu_online, cpu), true);
-}
+ struct srcu_data *sdp = container_of(t, struct srcu_data, delay_work);
-void srcu_offline_cpu(unsigned int cpu)
-{
- WRITE_ONCE(per_cpu(srcu_online, cpu), false);
+ queue_work_on(sdp->cpu, rcu_gp_wq, &sdp->work);
}
-/*
- * Place the workqueue handler on the specified CPU if online, otherwise
- * just run it whereever. This is useful for placing workqueue handlers
- * that are to invoke the specified CPU's callbacks.
- */
-static bool srcu_queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
- struct delayed_work *dwork,
+static void srcu_queue_delayed_work_on(struct srcu_data *sdp,
unsigned long delay)
{
- bool ret;
+ if (!delay) {
+ queue_work_on(sdp->cpu, rcu_gp_wq, &sdp->work);
+ return;
+ }
- preempt_disable();
- if (READ_ONCE(per_cpu(srcu_online, cpu)))
- ret = queue_delayed_work_on(cpu, wq, dwork, delay);
- else
- ret = queue_delayed_work(wq, dwork, delay);
- preempt_enable();
- return ret;
+ timer_reduce(&sdp->delay_work, jiffies + delay);
}
/*
@@ -504,7 +483,7 @@ static bool srcu_queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
*/
static void srcu_schedule_cbs_sdp(struct srcu_data *sdp, unsigned long delay)
{
- srcu_queue_delayed_work_on(sdp->cpu, rcu_gp_wq, &sdp->work, delay);
+ srcu_queue_delayed_work_on(sdp, delay);
}
/*
@@ -1186,7 +1165,8 @@ static void srcu_invoke_callbacks(struct work_struct *work)
struct srcu_data *sdp;
struct srcu_struct *ssp;
- sdp = container_of(work, struct srcu_data, work.work);
+ sdp = container_of(work, struct srcu_data, work);
+
ssp = sdp->ssp;
rcu_cblist_init(&ready_cbs);
spin_lock_irq_rcu_node(sdp);
diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c
index be10036fa621..a8304d90573f 100644
--- a/kernel/rcu/sync.c
+++ b/kernel/rcu/sync.c
@@ -1,20 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* RCU-based infrastructure for lightweight reader-writer locking
*
- * 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 (c) 2015, Red Hat, Inc.
*
* Author: Oleg Nesterov <oleg@redhat.com>
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 5f5963ba313e..911bd9076d43 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
@@ -76,7 +63,7 @@ void rcu_qs(void)
* 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_qs();
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 1c4add096078..3b084dbfb4bc 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1,27 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Read-Copy Update mechanism for mutual exclusion
*
- * 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
*
* Authors: Dipankar Sarma <dipankar@in.ibm.com>
* Manfred Spraul <manfred@colorfullife.com>
- * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version
+ * Paul E. McKenney <paulmck@linux.ibm.com> Hierarchical version
*
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
*
* For detailed explanation of Read-Copy Update mechanism see -
@@ -725,7 +712,6 @@ static __always_inline void rcu_nmi_exit_common(bool irq)
/**
* rcu_nmi_exit - inform RCU of exit from NMI context
- * @irq: Is this call from rcu_irq_exit?
*
* If you add or remove a call to rcu_nmi_exit(), be sure to test
* with CONFIG_RCU_EQS_DEBUG=y.
@@ -1139,7 +1125,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
}
/*
- * NO_HZ_FULL CPUs can run in-kernel without rcu_check_callbacks!
+ * NO_HZ_FULL CPUs can run in-kernel without rcu_sched_clock_irq!
* The above code handles this, but only for straight cond_resched().
* And some in-kernel loops check need_resched() before calling
* cond_resched(), which defeats the above code for CPUs that are
@@ -2532,14 +2518,14 @@ static void rcu_do_batch(struct rcu_data *rdp)
}
/*
- * Check to see if this CPU is in a non-context-switch quiescent state
- * (user mode or idle loop for rcu, non-softirq execution for rcu_bh).
- * Also schedule RCU core processing.
- *
- * This function must be called from hardirq context. It is normally
- * invoked from the scheduling-clock interrupt.
+ * This function is invoked from each scheduling-clock interrupt,
+ * and checks to see if this CPU is in a non-context-switch quiescent
+ * state, for example, user mode or idle loop. It also schedules RCU
+ * core processing. If the current grace period has gone on too long,
+ * it will ask the scheduler to manufacture a context switch for the sole
+ * purpose of providing a providing the needed quiescent state.
*/
-void rcu_check_callbacks(int user)
+void rcu_sched_clock_irq(int user)
{
trace_rcu_utilization(TPS("Start scheduler-tick"));
raw_cpu_inc(rcu_data.ticks_this_gp);
@@ -2552,7 +2538,7 @@ void rcu_check_callbacks(int user)
}
__this_cpu_write(rcu_data.rcu_urgent_qs, false);
}
- rcu_flavor_check_callbacks(user);
+ rcu_flavor_sched_clock_irq(user);
if (rcu_pending())
invoke_rcu_core();
@@ -2742,12 +2728,8 @@ void rcu_fwd_progress_check(unsigned long j)
}
EXPORT_SYMBOL_GPL(rcu_fwd_progress_check);
-/*
- * This does the RCU core processing work for the specified rcu_data
- * structures. This may be called only from the CPU to whom the rdp
- * belongs.
- */
-static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
+/* Perform RCU core processing work for the current CPU. */
+static __latent_entropy void rcu_core(struct softirq_action *unused)
{
unsigned long flags;
struct rcu_data *rdp = raw_cpu_ptr(&rcu_data);
@@ -3408,8 +3390,6 @@ int rcutree_online_cpu(unsigned int cpu)
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rnp->ffmask |= rdp->grpmask;
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
- if (IS_ENABLED(CONFIG_TREE_SRCU))
- srcu_online_cpu(cpu);
if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE)
return 0; /* Too early in boot for scheduler work. */
sync_sched_exp_online_cleanup(cpu);
@@ -3434,8 +3414,6 @@ int rcutree_offline_cpu(unsigned int cpu)
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
rcutree_affinity_setting(cpu, cpu);
- if (IS_ENABLED(CONFIG_TREE_SRCU))
- srcu_offline_cpu(cpu);
return 0;
}
@@ -3856,7 +3834,7 @@ void __init rcu_init(void)
rcu_init_one();
if (dump_tree)
rcu_dump_rcu_node_tree();
- open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+ open_softirq(RCU_SOFTIRQ, rcu_core);
/*
* We don't need protection against CPU-hotplug here because
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 149557b7c39c..bb4f995f2d3f 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -1,25 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Read-Copy Update mechanism for mutual exclusion (tree-based version)
* Internal non-public definitions.
*
- * 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: Ingo Molnar <mingo@elte.hu>
- * Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Paul E. McKenney <paulmck@linux.ibm.com>
*/
#include <linux/cache.h>
@@ -417,7 +404,7 @@ static void rcu_print_detail_task_stall(void);
static int rcu_print_task_stall(struct rcu_node *rnp);
static int rcu_print_task_exp_stall(struct rcu_node *rnp);
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
-static void rcu_flavor_check_callbacks(int user);
+static void rcu_flavor_sched_clock_irq(int user);
void call_rcu(struct rcu_head *head, rcu_callback_t func);
static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck);
static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
@@ -458,11 +445,3 @@ static void rcu_bind_gp_kthread(void);
static bool rcu_nohz_full_cpu(void);
static void rcu_dynticks_task_enter(void);
static void rcu_dynticks_task_exit(void);
-
-#ifdef CONFIG_SRCU
-void srcu_online_cpu(unsigned int cpu);
-void srcu_offline_cpu(unsigned int cpu);
-#else /* #ifdef CONFIG_SRCU */
-void srcu_online_cpu(unsigned int cpu) { }
-void srcu_offline_cpu(unsigned int cpu) { }
-#endif /* #else #ifdef CONFIG_SRCU */
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index d882ca0cd01b..4c2a0189e748 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -1,23 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
/*
* RCU expedited grace periods
*
- * 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, 2016
*
- * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
*/
#include <linux/lockdep.h>
@@ -448,7 +435,6 @@ static void sync_rcu_exp_select_cpus(void)
continue;
}
INIT_WORK(&rnp->rew.rew_work, sync_rcu_exp_select_node_cpus);
- preempt_disable();
cpu = find_next_bit(&rnp->ffmask, BITS_PER_LONG, -1);
/* If all offline, queue the work on an unbound CPU. */
if (unlikely(cpu > rnp->grphi - rnp->grplo))
@@ -456,7 +442,6 @@ static void sync_rcu_exp_select_cpus(void)
else
cpu += rnp->grplo;
queue_work_on(cpu, rcu_par_gp_wq, &rnp->rew.rew_work);
- preempt_enable();
rnp->exp_need_flush = true;
}
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 8ceed9e25ad5..97dba50f6fb2 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1,27 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Read-Copy Update mechanism for mutual exclusion (tree-based version)
* Internal non-public definitions that provide either classic
* or preemptible semantics.
*
- * 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 Red Hat, 2009
* Copyright IBM Corporation, 2009
*
* Author: Ingo Molnar <mingo@elte.hu>
- * Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Paul E. McKenney <paulmck@linux.ibm.com>
*/
#include <linux/delay.h>
@@ -297,7 +284,7 @@ static void rcu_qs(void)
__this_cpu_read(rcu_data.gp_seq),
TPS("cpuqs"));
__this_cpu_write(rcu_data.cpu_no_qs.b.norm, false);
- barrier(); /* Coordinate with rcu_flavor_check_callbacks(). */
+ barrier(); /* Coordinate with rcu_flavor_sched_clock_irq(). */
current->rcu_read_unlock_special.b.need_qs = false;
}
}
@@ -778,13 +765,13 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
}
/*
- * Check for a quiescent state from the current CPU. When a task blocks,
- * the task is recorded in the corresponding CPU's rcu_node structure,
- * which is checked elsewhere.
- *
- * Caller must disable hard irqs.
+ * Check for a quiescent state from the current CPU, including voluntary
+ * context switches for Tasks RCU. When a task blocks, the task is
+ * recorded in the corresponding CPU's rcu_node structure, which is checked
+ * elsewhere, hence this function need only check for quiescent states
+ * related to the current CPU, not to those related to tasks.
*/
-static void rcu_flavor_check_callbacks(int user)
+static void rcu_flavor_sched_clock_irq(int user)
{
struct task_struct *t = current;
@@ -1030,14 +1017,10 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
}
/*
- * Check to see if this CPU is in a non-context-switch quiescent state
- * (user mode or idle loop for rcu, non-softirq execution for rcu_bh).
- * Also schedule RCU core processing.
- *
- * This function must be called from hardirq context. It is normally
- * invoked from the scheduling-clock interrupt.
+ * Check to see if this CPU is in a non-context-switch quiescent state,
+ * namely user mode and idle loop.
*/
-static void rcu_flavor_check_callbacks(int user)
+static void rcu_flavor_sched_clock_irq(int user)
{
if (user || rcu_is_cpu_rrupt_from_idle()) {
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 1971869c4072..e3c6395c9b4c 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -1,26 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* Read-Copy Update mechanism for mutual exclusion
*
- * 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, 2001
*
* Authors: Dipankar Sarma <dipankar@in.ibm.com>
* Manfred Spraul <manfred@colorfullife.com>
*
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
* Papers:
* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf