[PATCH 15/18] rcu: Standardize explicit CPU-hotplug calls
From: Frederic Weisbecker
Date: Fri Oct 13 2023 - 08:00:58 EST
rcu_report_dead() and rcutree_migrate_callbacks() have their headers in
rcupdate.h while those are pure rcutree calls, like the other CPU-hotplug
functions.
Also rcu_cpu_starting() and rcu_report_dead() have different naming
conventions while they mirror each other's effects.
Fix the headers and propose a naming that relates both functions and
aligns with the prefix of other rcutree CPU-hotplug functions.
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
---
.../Expedited-Grace-Periods.rst | 2 +-
.../RCU/Design/Memory-Ordering/TreeRCU-gp-fqs.svg | 4 ++--
.../RCU/Design/Memory-Ordering/TreeRCU-gp.svg | 4 ++--
.../RCU/Design/Memory-Ordering/TreeRCU-hotplug.svg | 4 ++--
.../RCU/Design/Requirements/Requirements.rst | 4 ++--
arch/arm64/kernel/smp.c | 4 ++--
arch/powerpc/kernel/smp.c | 2 +-
arch/s390/kernel/smp.c | 2 +-
arch/x86/kernel/smpboot.c | 2 +-
include/linux/interrupt.h | 2 +-
include/linux/rcupdate.h | 2 --
include/linux/rcutiny.h | 2 +-
include/linux/rcutree.h | 7 ++++++-
kernel/cpu.c | 6 +++---
kernel/rcu/tree.c | 12 ++++++++----
15 files changed, 33 insertions(+), 26 deletions(-)
diff --git a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
index 93d899d53258..414f8a2012d6 100644
--- a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
+++ b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst
@@ -181,7 +181,7 @@ operations is carried out at several levels:
of this wait (or series of waits, as the case may be) is to permit a
concurrent CPU-hotplug operation to complete.
#. In the case of RCU-sched, one of the last acts of an outgoing CPU is
- to invoke ``rcu_report_dead()``, which reports a quiescent state for
+ to invoke ``rcutree_report_cpu_dead()``, which reports a quiescent state for
that CPU. However, this is likely paranoia-induced redundancy.
+-----------------------------------------------------------------------+
diff --git a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp-fqs.svg b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp-fqs.svg
index 7ddc094d7f28..d82a77d03d8c 100644
--- a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp-fqs.svg
+++ b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp-fqs.svg
@@ -1135,7 +1135,7 @@
font-weight="bold"
font-size="192"
id="text202-7-5-3-27-6-5"
- style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_report_dead()</text>
+ style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcutree_report_cpu_dead()</text>
<text
xml:space="preserve"
x="3745.7725"
@@ -1256,7 +1256,7 @@
font-style="normal"
y="3679.27"
x="-3804.9949"
- xml:space="preserve">rcu_cpu_starting()</text>
+ xml:space="preserve">rcutree_report_cpu_starting()</text>
<g
style="fill:none;stroke-width:0.025in"
id="g3107-7-5-0"
diff --git a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg
index 069f6f8371c2..6e690a3be161 100644
--- a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg
+++ b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg
@@ -3274,7 +3274,7 @@
font-weight="bold"
font-size="192"
id="text202-7-5-3-27-6-5"
- style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_report_dead()</text>
+ style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcutree_report_cpu_dead()</text>
<text
xml:space="preserve"
x="3745.7725"
@@ -3395,7 +3395,7 @@
font-style="normal"
y="3679.27"
x="-3804.9949"
- xml:space="preserve">rcu_cpu_starting()</text>
+ xml:space="preserve">rcutree_report_cpu_starting()</text>
<g
style="fill:none;stroke-width:0.025in"
id="g3107-7-5-0"
diff --git a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-hotplug.svg b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-hotplug.svg
index 2c9310ba29ba..4fa7506082bf 100644
--- a/Documentation/RCU/Design/Memory-Ordering/TreeRCU-hotplug.svg
+++ b/Documentation/RCU/Design/Memory-Ordering/TreeRCU-hotplug.svg
@@ -607,7 +607,7 @@
font-weight="bold"
font-size="192"
id="text202-7-5-3-27-6"
- style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_report_dead()</text>
+ style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcutree_report_cpu_dead()</text>
<text
xml:space="preserve"
x="3745.7725"
@@ -728,7 +728,7 @@
font-style="normal"
y="3679.27"
x="-3804.9949"
- xml:space="preserve">rcu_cpu_starting()</text>
+ xml:space="preserve">rcutree_report_cpu_starting()</text>
<g
style="fill:none;stroke-width:0.025in"
id="g3107-7-5-0"
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst
index f3b605285a87..cccafdaa1f84 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.rst
+++ b/Documentation/RCU/Design/Requirements/Requirements.rst
@@ -1955,12 +1955,12 @@ if offline CPUs block an RCU grace period for too long.
An offline CPU's quiescent state will be reported either:
-1. As the CPU goes offline using RCU's hotplug notifier (rcu_report_dead()).
+1. As the CPU goes offline using RCU's hotplug notifier (rcutree_report_cpu_dead()).
2. When grace period initialization (rcu_gp_init()) detects a
race either with CPU offlining or with a task unblocking on a leaf
``rcu_node`` structure whose CPUs are all offline.
-The CPU-online path (rcu_cpu_starting()) should never need to report
+The CPU-online path (rcutree_report_cpu_starting()) should never need to report
a quiescent state for an offline CPU. However, as a debugging measure,
it does emit a warning if a quiescent state was not already reported
for that CPU.
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 8fa646c90c67..196533c362e1 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -215,7 +215,7 @@ asmlinkage notrace void secondary_start_kernel(void)
if (system_uses_irq_prio_masking())
init_gic_priority_masking();
- rcu_cpu_starting(cpu);
+ rcutree_report_cpu_starting(cpu);
trace_hardirqs_off();
/*
@@ -401,7 +401,7 @@ void __noreturn cpu_die_early(void)
/* Mark this CPU absent */
set_cpu_present(cpu, 0);
- rcu_report_dead();
+ rcutree_report_cpu_dead();
if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) {
update_cpu_boot_status(CPU_KILL_ME);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 5826f5108a12..a30d4d93ff0b 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1629,7 +1629,7 @@ void start_secondary(void *unused)
smp_store_cpu_info(cpu);
set_dec(tb_ticks_per_jiffy);
- rcu_cpu_starting(cpu);
+ rcutree_report_cpu_starting(cpu);
cpu_callin_map[cpu] = 1;
if (smp_ops->setup_cpu)
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index a4edb7ea66ea..214a1b67f80a 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -898,7 +898,7 @@ static void smp_start_secondary(void *cpuvoid)
S390_lowcore.restart_flags = 0;
restore_access_regs(S390_lowcore.access_regs_save_area);
cpu_init();
- rcu_cpu_starting(cpu);
+ rcutree_report_cpu_starting(cpu);
init_cpu_timer();
vtime_init();
vdso_getcpu_init();
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 4e45ff44aa07..4ccb76f89af8 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -288,7 +288,7 @@ static void notrace start_secondary(void *unused)
cpu_init();
fpu__init_cpu();
- rcu_cpu_starting(raw_smp_processor_id());
+ rcutree_report_cpu_starting(raw_smp_processor_id());
x86_cpuinit.early_percpu_clock_init();
ap_starting();
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index a92bce40b04b..d05e1e9a553c 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -566,7 +566,7 @@ enum
*
* _ RCU:
* 1) rcutree_migrate_callbacks() migrates the queue.
- * 2) rcu_report_dead() reports the final quiescent states.
+ * 2) rcutree_report_cpu_dead() reports the final quiescent states.
*
* _ IRQ_POLL: irq_poll_cpu_dead() migrates the queue
*/
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index aa351ddcbe8d..f7206b2623c9 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -122,8 +122,6 @@ static inline void call_rcu_hurry(struct rcu_head *head, rcu_callback_t func)
void rcu_init(void);
extern int rcu_scheduler_active;
void rcu_sched_clock_irq(int user);
-void rcu_report_dead(void);
-void rcutree_migrate_callbacks(int cpu);
#ifdef CONFIG_TASKS_RCU_GENERIC
void rcu_init_tasks_generic(void);
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 7b949292908a..d9ac7b136aea 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -171,6 +171,6 @@ static inline void rcu_all_qs(void) { barrier(); }
#define rcutree_offline_cpu NULL
#define rcutree_dead_cpu NULL
#define rcutree_dying_cpu NULL
-static inline void rcu_cpu_starting(unsigned int cpu) { }
+static inline void rcutree_report_cpu_starting(unsigned int cpu) { }
#endif /* __LINUX_RCUTINY_H */
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 46875c4e9f56..254244202ea9 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -110,7 +110,7 @@ void rcu_all_qs(void);
/* RCUtree hotplug events */
int rcutree_prepare_cpu(unsigned int cpu);
int rcutree_online_cpu(unsigned int cpu);
-void rcu_cpu_starting(unsigned int cpu);
+void rcutree_report_cpu_starting(unsigned int cpu);
#ifdef CONFIG_HOTPLUG_CPU
int rcutree_dead_cpu(unsigned int cpu);
@@ -122,4 +122,9 @@ int rcutree_offline_cpu(unsigned int cpu);
#define rcutree_offline_cpu NULL
#endif
+void rcutree_migrate_callbacks(int cpu);
+
+/* Called from hotplug and also arm64 early secondary boot failure */
+void rcutree_report_cpu_dead(void);
+
#endif /* __LINUX_RCUTREE_H */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 076e75fed8bb..2491766e1fd5 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1388,10 +1388,10 @@ void cpuhp_report_idle_dead(void)
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
BUG_ON(st->state != CPUHP_AP_OFFLINE);
- rcu_report_dead();
+ rcutree_report_cpu_dead();
st->state = CPUHP_AP_IDLE_DEAD;
/*
- * We cannot call complete after rcu_report_dead() so we delegate it
+ * We cannot call complete after rcutree_report_cpu_dead() so we delegate it
* to an online cpu.
*/
smp_call_function_single(cpumask_first(cpu_online_mask),
@@ -1617,7 +1617,7 @@ void notify_cpu_starting(unsigned int cpu)
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
- rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
+ rcutree_report_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
cpumask_set_cpu(cpu, &cpus_booted_once_mask);
/*
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index f9c6b2680cbb..36d8818eaec1 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4216,7 +4216,7 @@ bool rcu_lockdep_current_cpu_online(void)
rdp = this_cpu_ptr(&rcu_data);
/*
* Strictly, we care here about the case where the current CPU is
- * in rcu_cpu_starting() and thus has an excuse for rdp->grpmask
+ * in rcutree_report_cpu_starting() and thus has an excuse for rdp->grpmask
* not being up to date. So arch_spin_is_locked() might have a
* false positive if it's held by some *other* CPU, but that's
* OK because that just means a false *negative* on the warning.
@@ -4445,8 +4445,10 @@ int rcutree_online_cpu(unsigned int cpu)
* from the incoming CPU rather than from the cpuhp_step mechanism.
* This is because this function must be invoked at a precise location.
* This incoming CPU must not have enabled interrupts yet.
+ *
+ * This mirrors the effects of rcutree_report_cpu_dead().
*/
-void rcu_cpu_starting(unsigned int cpu)
+void rcutree_report_cpu_starting(unsigned int cpu)
{
unsigned long mask;
struct rcu_data *rdp;
@@ -4500,8 +4502,10 @@ void rcu_cpu_starting(unsigned int cpu)
* Note that this function is special in that it is invoked directly
* from the outgoing CPU rather than from the cpuhp_step mechanism.
* This is because this function must be invoked at a precise location.
+ *
+ * This mirrors the effect of rcutree_report_cpu_starting().
*/
-void rcu_report_dead(void)
+void rcutree_report_cpu_dead(void)
{
unsigned long flags;
unsigned long mask;
@@ -5072,7 +5076,7 @@ void __init rcu_init(void)
pm_notifier(rcu_pm_notify, 0);
WARN_ON(num_online_cpus() > 1); // Only one CPU this early in boot.
rcutree_prepare_cpu(cpu);
- rcu_cpu_starting(cpu);
+ rcutree_report_cpu_starting(cpu);
rcutree_online_cpu(cpu);
/* Create workqueue for Tree SRCU and for expedited GPs. */
--
2.34.1