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authorLinus Torvalds <torvalds@linux-foundation.org>2013-12-04 08:52:09 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-12-04 08:52:09 -0800
commit1ab231b274ba51a54acebec23c6aded0f3cdf54e (patch)
tree2ce15cb4ba9adf3e041eb9d1b26f63292c953094
parentdea4f48a0a301b23c65af8e4fe8ccf360c272fbf (diff)
parent0e576acbc1d9600cf2d9b4a141a2554639959d50 (diff)
downloadlinux-stericsson-1ab231b274ba51a54acebec23c6aded0f3cdf54e.tar.gz
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Thomas Gleixner: - timekeeping: Cure a subtle drift issue on GENERIC_TIME_VSYSCALL_OLD - nohz: Make CONFIG_NO_HZ=n and nohz=off command line option behave the same way. Fixes a long standing load accounting wreckage. - clocksource/ARM: Kconfig update to avoid ARM=n wreckage - clocksource/ARM: Fixlets for the AT91 and SH clocksource/clockevents - Trivial documentation update and kzalloc conversion from akpms pile * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off time: Fix 1ns/tick drift w/ GENERIC_TIME_VSYSCALL_OLD clocksource: arm_arch_timer: Hide eventstream Kconfig on non-ARM clocksource: sh_tmu: Add clk_prepare/unprepare support clocksource: sh_tmu: Release clock when sh_tmu_register() fails clocksource: sh_mtu2: Add clk_prepare/unprepare support clocksource: sh_mtu2: Release clock when sh_mtu2_register() fails ARM: at91: rm9200: switch back to clockevents_config_and_register tick: Document tick_do_timer_cpu timer: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...) NOHZ: Check for nohz active instead of nohz enabled
-rw-r--r--arch/arm/mach-at91/at91rm9200_time.c7
-rw-r--r--drivers/clocksource/Kconfig1
-rw-r--r--drivers/clocksource/sh_mtu2.c16
-rw-r--r--drivers/clocksource/sh_tmu.c20
-rw-r--r--kernel/rcu/tree_plugin.h4
-rw-r--r--kernel/time/tick-common.c15
-rw-r--r--kernel/time/tick-sched.c25
-rw-r--r--kernel/time/timekeeping.c2
-rw-r--r--kernel/timer.c5
9 files changed, 66 insertions, 29 deletions
diff --git a/arch/arm/mach-at91/at91rm9200_time.c b/arch/arm/mach-at91/at91rm9200_time.c
index f607deb40f4d..bc7b363a3083 100644
--- a/arch/arm/mach-at91/at91rm9200_time.c
+++ b/arch/arm/mach-at91/at91rm9200_time.c
@@ -174,7 +174,6 @@ clkevt32k_next_event(unsigned long delta, struct clock_event_device *dev)
static struct clock_event_device clkevt = {
.name = "at91_tick",
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
- .shift = 32,
.rating = 150,
.set_next_event = clkevt32k_next_event,
.set_mode = clkevt32k_mode,
@@ -265,11 +264,9 @@ void __init at91rm9200_timer_init(void)
at91_st_write(AT91_ST_RTMR, 1);
/* Setup timer clockevent, with minimum of two ticks (important!!) */
- clkevt.mult = div_sc(AT91_SLOW_CLOCK, NSEC_PER_SEC, clkevt.shift);
- clkevt.max_delta_ns = clockevent_delta2ns(AT91_ST_ALMV, &clkevt);
- clkevt.min_delta_ns = clockevent_delta2ns(2, &clkevt) + 1;
clkevt.cpumask = cpumask_of(0);
- clockevents_register_device(&clkevt);
+ clockevents_config_and_register(&clkevt, AT91_SLOW_CLOCK,
+ 2, AT91_ST_ALMV);
/* register clocksource */
clocksource_register_hz(&clk32k, AT91_SLOW_CLOCK);
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index bdb953e15d2a..5c07a56962db 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -87,6 +87,7 @@ config ARM_ARCH_TIMER
config ARM_ARCH_TIMER_EVTSTREAM
bool "Support for ARM architected timer event stream generation"
default y if ARM_ARCH_TIMER
+ depends on ARM_ARCH_TIMER
help
This option enables support for event stream generation based on
the ARM architected timer. It is used for waking up CPUs executing
diff --git a/drivers/clocksource/sh_mtu2.c b/drivers/clocksource/sh_mtu2.c
index 4aac9ee0d0c0..3cf12834681e 100644
--- a/drivers/clocksource/sh_mtu2.c
+++ b/drivers/clocksource/sh_mtu2.c
@@ -313,8 +313,20 @@ static int sh_mtu2_setup(struct sh_mtu2_priv *p, struct platform_device *pdev)
goto err1;
}
- return sh_mtu2_register(p, (char *)dev_name(&p->pdev->dev),
- cfg->clockevent_rating);
+ ret = clk_prepare(p->clk);
+ if (ret < 0)
+ goto err2;
+
+ ret = sh_mtu2_register(p, (char *)dev_name(&p->pdev->dev),
+ cfg->clockevent_rating);
+ if (ret < 0)
+ goto err3;
+
+ return 0;
+ err3:
+ clk_unprepare(p->clk);
+ err2:
+ clk_put(p->clk);
err1:
iounmap(p->mapbase);
err0:
diff --git a/drivers/clocksource/sh_tmu.c b/drivers/clocksource/sh_tmu.c
index 78b8dae49628..63557cda0a7d 100644
--- a/drivers/clocksource/sh_tmu.c
+++ b/drivers/clocksource/sh_tmu.c
@@ -472,12 +472,26 @@ static int sh_tmu_setup(struct sh_tmu_priv *p, struct platform_device *pdev)
ret = PTR_ERR(p->clk);
goto err1;
}
+
+ ret = clk_prepare(p->clk);
+ if (ret < 0)
+ goto err2;
+
p->cs_enabled = false;
p->enable_count = 0;
- return sh_tmu_register(p, (char *)dev_name(&p->pdev->dev),
- cfg->clockevent_rating,
- cfg->clocksource_rating);
+ ret = sh_tmu_register(p, (char *)dev_name(&p->pdev->dev),
+ cfg->clockevent_rating,
+ cfg->clocksource_rating);
+ if (ret < 0)
+ goto err3;
+
+ return 0;
+
+ err3:
+ clk_unprepare(p->clk);
+ err2:
+ clk_put(p->clk);
err1:
iounmap(p->mapbase);
err0:
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 6abb03dff5c0..08a765232432 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1632,7 +1632,7 @@ module_param(rcu_idle_gp_delay, int, 0644);
static int rcu_idle_lazy_gp_delay = RCU_IDLE_LAZY_GP_DELAY;
module_param(rcu_idle_lazy_gp_delay, int, 0644);
-extern int tick_nohz_enabled;
+extern int tick_nohz_active;
/*
* Try to advance callbacks for all flavors of RCU on the current CPU, but
@@ -1729,7 +1729,7 @@ static void rcu_prepare_for_idle(int cpu)
int tne;
/* Handle nohz enablement switches conservatively. */
- tne = ACCESS_ONCE(tick_nohz_enabled);
+ tne = ACCESS_ONCE(tick_nohz_active);
if (tne != rdtp->tick_nohz_enabled_snap) {
if (rcu_cpu_has_callbacks(cpu, NULL))
invoke_rcu_core(); /* force nohz to see update. */
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 64522ecdfe0e..162b03ab0ad2 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -33,6 +33,21 @@ DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
*/
ktime_t tick_next_period;
ktime_t tick_period;
+
+/*
+ * tick_do_timer_cpu is a timer core internal variable which holds the CPU NR
+ * which is responsible for calling do_timer(), i.e. the timekeeping stuff. This
+ * variable has two functions:
+ *
+ * 1) Prevent a thundering herd issue of a gazillion of CPUs trying to grab the
+ * timekeeping lock all at once. Only the CPU which is assigned to do the
+ * update is handling it.
+ *
+ * 2) Hand off the duty in the NOHZ idle case by setting the value to
+ * TICK_DO_TIMER_NONE, i.e. a non existing CPU. So the next cpu which looks
+ * at it will take over and keep the time keeping alive. The handover
+ * procedure also covers cpu hotplug.
+ */
int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
/*
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 3612fc77f834..ea20f7d1ac2c 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -361,8 +361,8 @@ void __init tick_nohz_init(void)
/*
* NO HZ enabled ?
*/
-int tick_nohz_enabled __read_mostly = 1;
-
+static int tick_nohz_enabled __read_mostly = 1;
+int tick_nohz_active __read_mostly;
/*
* Enable / Disable tickless mode
*/
@@ -465,7 +465,7 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
ktime_t now, idle;
- if (!tick_nohz_enabled)
+ if (!tick_nohz_active)
return -1;
now = ktime_get();
@@ -506,7 +506,7 @@ u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
ktime_t now, iowait;
- if (!tick_nohz_enabled)
+ if (!tick_nohz_active)
return -1;
now = ktime_get();
@@ -711,8 +711,10 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
return false;
}
- if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
+ if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) {
+ ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ };
return false;
+ }
if (need_resched())
return false;
@@ -799,11 +801,6 @@ void tick_nohz_idle_enter(void)
local_irq_disable();
ts = &__get_cpu_var(tick_cpu_sched);
- /*
- * set ts->inidle unconditionally. even if the system did not
- * switch to nohz mode the cpu frequency governers rely on the
- * update of the idle time accounting in tick_nohz_start_idle().
- */
ts->inidle = 1;
__tick_nohz_idle_enter(ts);
@@ -973,7 +970,7 @@ static void tick_nohz_switch_to_nohz(void)
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
ktime_t next;
- if (!tick_nohz_enabled)
+ if (!tick_nohz_active)
return;
local_irq_disable();
@@ -981,7 +978,7 @@ static void tick_nohz_switch_to_nohz(void)
local_irq_enable();
return;
}
-
+ tick_nohz_active = 1;
ts->nohz_mode = NOHZ_MODE_LOWRES;
/*
@@ -1139,8 +1136,10 @@ void tick_setup_sched_timer(void)
}
#ifdef CONFIG_NO_HZ_COMMON
- if (tick_nohz_enabled)
+ if (tick_nohz_enabled) {
ts->nohz_mode = NOHZ_MODE_HIGHRES;
+ tick_nohz_active = 1;
+ }
#endif
}
#endif /* HIGH_RES_TIMERS */
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 3abf53418b67..87b4f00284c9 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1347,7 +1347,7 @@ static inline void old_vsyscall_fixup(struct timekeeper *tk)
tk->xtime_nsec -= remainder;
tk->xtime_nsec += 1ULL << tk->shift;
tk->ntp_error += remainder << tk->ntp_error_shift;
-
+ tk->ntp_error -= (1ULL << tk->shift) << tk->ntp_error_shift;
}
#else
#define old_vsyscall_fixup(tk)
diff --git a/kernel/timer.c b/kernel/timer.c
index 6582b82fa966..accfd241b9e5 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1518,9 +1518,8 @@ static int init_timers_cpu(int cpu)
/*
* The APs use this path later in boot
*/
- base = kmalloc_node(sizeof(*base),
- GFP_KERNEL | __GFP_ZERO,
- cpu_to_node(cpu));
+ base = kzalloc_node(sizeof(*base), GFP_KERNEL,
+ cpu_to_node(cpu));
if (!base)
return -ENOMEM;