From fe0f49768d807a8fe6336b097feb8c4441951710 Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Tue, 30 Sep 2014 17:37:52 +0200
Subject: [PATCH] s390/nohz: use a per-cpu flag for arch_needs_cpu
Move the nohz_delay bit from the s390_idle data structure to the
per-cpu flags. Clear the nohz delay flag in __cpu_disable and
remove the cpu hotplug notifier that used to do this.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/include/asm/cputime.h | 8 --------
arch/s390/include/asm/processor.h | 4 ++++
arch/s390/kernel/irq.c | 2 +-
arch/s390/kernel/smp.c | 1 +
arch/s390/kernel/vtime.c | 19 +------------------
drivers/s390/cio/airq.c | 2 +-
drivers/s390/cio/cio.c | 2 +-
include/linux/tick.h | 2 +-
kernel/time/tick-sched.c | 2 +-
9 files changed, 11 insertions(+), 31 deletions(-)
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index f65bd36345194..01887b1fade59 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -166,7 +166,6 @@ static inline clock_t cputime64_to_clock_t(cputime64_t cputime)
}
struct s390_idle_data {
- int nohz_delay;
unsigned int sequence;
unsigned long long idle_count;
unsigned long long idle_time;
@@ -182,11 +181,4 @@ cputime64_t s390_get_idle_time(int cpu);
#define arch_idle_time(cpu) s390_get_idle_time(cpu)
-static inline int s390_nohz_delay(int cpu)
-{
- return __get_cpu_var(s390_idle).nohz_delay != 0;
-}
-
-#define arch_needs_cpu(cpu) s390_nohz_delay(cpu)
-
#endif /* _S390_CPUTIME_H */
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index e568fc8a72506..bc796d73129bf 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -13,9 +13,11 @@
#define CIF_MCCK_PENDING 0 /* machine check handling is pending */
#define CIF_ASCE 1 /* user asce needs fixup / uaccess */
+#define CIF_NOHZ_DELAY 2 /* delay HZ disable for a tick */
#define _CIF_MCCK_PENDING (1<<CIF_MCCK_PENDING)
#define _CIF_ASCE (1<<CIF_ASCE)
+#define _CIF_NOHZ_DELAY (1<<CIF_NOHZ_DELAY)
#ifndef __ASSEMBLY__
@@ -43,6 +45,8 @@ static inline int test_cpu_flag(int flag)
return !!(S390_lowcore.cpu_flags & (1U << flag));
}
+#define arch_needs_cpu() test_cpu_flag(CIF_NOHZ_DELAY)
+
/*
* Default implementation of macro that returns current
* instruction pointer ("program counter").
diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 051574ee53661..1b8a38ab7861c 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -259,7 +259,7 @@ static irqreturn_t do_ext_interrupt(int irq, void *dummy)
ext_code = *(struct ext_code *) ®s->int_code;
if (ext_code.code != EXT_IRQ_CLK_COMP)
- __get_cpu_var(s390_idle).nohz_delay = 1;
+ set_cpu_flag(CIF_NOHZ_DELAY);
index = ext_hash(ext_code.code);
rcu_read_lock();
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index abec97b4ddbf4..46317d6951c4f 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -720,6 +720,7 @@ int __cpu_disable(void)
cregs[6] &= ~0xff000000UL; /* disable all I/O interrupts */
cregs[14] &= ~0x1f000000UL; /* disable most machine checks */
__ctl_load(cregs, 0, 15);
+ clear_cpu_flag(CIF_NOHZ_DELAY);
return 0;
}
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 8c34363d6f1e8..40709821abde6 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -163,7 +163,7 @@ void __kprobes vtime_stop_cpu(void)
/* Wait for external, I/O or machine check interrupt. */
psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
- idle->nohz_delay = 0;
+ clear_cpu_flag(CIF_NOHZ_DELAY);
/* Call the assembler magic in entry.S */
psw_idle(idle, psw_mask);
@@ -378,25 +378,8 @@ void init_cpu_vtimer(void)
set_vtimer(VTIMER_MAX_SLICE);
}
-static int s390_nohz_notify(struct notifier_block *self, unsigned long action,
- void *hcpu)
-{
- struct s390_idle_data *idle;
- long cpu = (long) hcpu;
-
- idle = &per_cpu(s390_idle, cpu);
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_DYING:
- idle->nohz_delay = 0;
- default:
- break;
- }
- return NOTIFY_OK;
-}
-
void __init vtime_init(void)
{
/* Enable cpu timer interrupts on the boot cpu. */
init_cpu_vtimer();
- cpu_notifier(s390_nohz_notify, 0);
}
diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index 00bfbee0af9e0..56eb4ee4deba0 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -87,7 +87,7 @@ static irqreturn_t do_airq_interrupt(int irq, void *dummy)
struct airq_struct *airq;
struct hlist_head *head;
- __this_cpu_write(s390_idle.nohz_delay, 1);
+ set_cpu_flag(CIF_NOHZ_DELAY);
tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
head = &airq_lists[tpi_info->isc];
rcu_read_lock();
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 2905d8b0ec95b..d5a6f287d2fed 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -561,7 +561,7 @@ static irqreturn_t do_cio_interrupt(int irq, void *dummy)
struct subchannel *sch;
struct irb *irb;
- __this_cpu_write(s390_idle.nohz_delay, 1);
+ set_cpu_flag(CIF_NOHZ_DELAY);
tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
irb = &__get_cpu_var(cio_irb);
sch = (struct subchannel *)(unsigned long) tpi_info->intparm;
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 9a82c7dc3fdd9..e5832d03da19d 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -108,7 +108,7 @@ extern struct tick_sched *tick_get_tick_sched(int cpu);
extern void tick_irq_enter(void);
extern int tick_oneshot_mode_active(void);
# ifndef arch_needs_cpu
-# define arch_needs_cpu(cpu) (0)
+# define arch_needs_cpu() (0)
# endif
# else
static inline void tick_clock_notify(void) { }
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f654a8a298fad..01d512fd45f1b 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -572,7 +572,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
} while (read_seqretry(&jiffies_lock, seq));
if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) ||
- arch_needs_cpu(cpu) || irq_work_needs_cpu()) {
+ arch_needs_cpu() || irq_work_needs_cpu()) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {