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-rw-r--r--kernel/Makefile1
-rw-r--r--kernel/context_tracking.c83
-rw-r--r--kernel/ksysfs.c18
-rw-r--r--kernel/rcu.h2
-rw-r--r--kernel/rcupdate.c3
-rw-r--r--kernel/rcutiny.c2
-rw-r--r--kernel/rcutiny_plugin.h5
-rw-r--r--kernel/rcutorture.c54
-rw-r--r--kernel/rcutree.c347
-rw-r--r--kernel/rcutree.h67
-rw-r--r--kernel/rcutree_plugin.h415
-rw-r--r--kernel/rcutree_trace.c330
-rw-r--r--kernel/sched/core.c23
-rw-r--r--kernel/srcu.c16
14 files changed, 1014 insertions, 352 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index 86e3285ae7e..ac0d533eb7d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -110,6 +110,7 @@ obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
obj-$(CONFIG_PADATA) += padata.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o
+obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
$(obj)/configs.o: $(obj)/config_data.h
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
new file mode 100644
index 00000000000..e0e07fd5550
--- /dev/null
+++ b/kernel/context_tracking.c
@@ -0,0 +1,83 @@
+#include <linux/context_tracking.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+
+struct context_tracking {
+ /*
+ * When active is false, hooks are not set to
+ * minimize overhead: TIF flags are cleared
+ * and calls to user_enter/exit are ignored. This
+ * may be further optimized using static keys.
+ */
+ bool active;
+ enum {
+ IN_KERNEL = 0,
+ IN_USER,
+ } state;
+};
+
+static DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
+#ifdef CONFIG_CONTEXT_TRACKING_FORCE
+ .active = true,
+#endif
+};
+
+void user_enter(void)
+{
+ unsigned long flags;
+
+ /*
+ * Some contexts may involve an exception occuring in an irq,
+ * leading to that nesting:
+ * rcu_irq_enter() rcu_user_exit() rcu_user_exit() rcu_irq_exit()
+ * This would mess up the dyntick_nesting count though. And rcu_irq_*()
+ * helpers are enough to protect RCU uses inside the exception. So
+ * just return immediately if we detect we are in an IRQ.
+ */
+ if (in_interrupt())
+ return;
+
+ WARN_ON_ONCE(!current->mm);
+
+ local_irq_save(flags);
+ if (__this_cpu_read(context_tracking.active) &&
+ __this_cpu_read(context_tracking.state) != IN_USER) {
+ __this_cpu_write(context_tracking.state, IN_USER);
+ rcu_user_enter();
+ }
+ local_irq_restore(flags);
+}
+
+void user_exit(void)
+{
+ unsigned long flags;
+
+ /*
+ * Some contexts may involve an exception occuring in an irq,
+ * leading to that nesting:
+ * rcu_irq_enter() rcu_user_exit() rcu_user_exit() rcu_irq_exit()
+ * This would mess up the dyntick_nesting count though. And rcu_irq_*()
+ * helpers are enough to protect RCU uses inside the exception. So
+ * just return immediately if we detect we are in an IRQ.
+ */
+ if (in_interrupt())
+ return;
+
+ local_irq_save(flags);
+ if (__this_cpu_read(context_tracking.state) == IN_USER) {
+ __this_cpu_write(context_tracking.state, IN_KERNEL);
+ rcu_user_exit();
+ }
+ local_irq_restore(flags);
+}
+
+void context_tracking_task_switch(struct task_struct *prev,
+ struct task_struct *next)
+{
+ if (__this_cpu_read(context_tracking.active)) {
+ clear_tsk_thread_flag(prev, TIF_NOHZ);
+ set_tsk_thread_flag(next, TIF_NOHZ);
+ }
+}
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index c01eac66c0c..6ada93c23a9 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -140,6 +140,23 @@ static ssize_t fscaps_show(struct kobject *kobj,
}
KERNEL_ATTR_RO(fscaps);
+int rcu_expedited;
+static ssize_t rcu_expedited_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", rcu_expedited);
+}
+static ssize_t rcu_expedited_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ if (kstrtoint(buf, 0, &rcu_expedited))
+ return -EINVAL;
+
+ return count;
+}
+KERNEL_ATTR_RW(rcu_expedited);
+
/*
* Make /sys/kernel/notes give the raw contents of our kernel .notes section.
*/
@@ -179,6 +196,7 @@ static struct attribute * kernel_attrs[] = {
&kexec_crash_size_attr.attr,
&vmcoreinfo_attr.attr,
#endif
+ &rcu_expedited_attr.attr,
NULL
};
diff --git a/kernel/rcu.h b/kernel/rcu.h
index 8ba99cdc651..20dfba576c2 100644
--- a/kernel/rcu.h
+++ b/kernel/rcu.h
@@ -109,4 +109,6 @@ static inline bool __rcu_reclaim(char *rn, struct rcu_head *head)
}
}
+extern int rcu_expedited;
+
#endif /* __LINUX_RCU_H */
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 29ca1c6da59..a2cf76177b4 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -46,12 +46,15 @@
#include <linux/export.h>
#include <linux/hardirq.h>
#include <linux/delay.h>
+#include <linux/module.h>
#define CREATE_TRACE_POINTS
#include <trace/events/rcu.h>
#include "rcu.h"
+module_param(rcu_expedited, int, 0);
+
#ifdef CONFIG_PREEMPT_RCU
/*
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index e4c6a598d6f..e7dce58f9c2 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -195,7 +195,7 @@ EXPORT_SYMBOL(rcu_is_cpu_idle);
*/
int rcu_is_cpu_rrupt_from_idle(void)
{
- return rcu_dynticks_nesting <= 0;
+ return rcu_dynticks_nesting <= 1;
}
/*
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index 3d019028220..f85016a2309 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -706,7 +706,10 @@ void synchronize_rcu(void)
return;
/* Once we get past the fastpath checks, same code as rcu_barrier(). */
- rcu_barrier();
+ if (rcu_expedited)
+ synchronize_rcu_expedited();
+ else
+ rcu_barrier();
}
EXPORT_SYMBOL_GPL(synchronize_rcu);
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index aaa7b9f3532..31dea01c85f 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -339,7 +339,6 @@ rcu_stutter_wait(char *title)
struct rcu_torture_ops {
void (*init)(void);
- void (*cleanup)(void);
int (*readlock)(void);
void (*read_delay)(struct rcu_random_state *rrsp);
void (*readunlock)(int idx);
@@ -431,7 +430,6 @@ static void rcu_torture_deferred_free(struct rcu_torture *p)
static struct rcu_torture_ops rcu_ops = {
.init = NULL,
- .cleanup = NULL,
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay,
.readunlock = rcu_torture_read_unlock,
@@ -475,7 +473,6 @@ static void rcu_sync_torture_init(void)
static struct rcu_torture_ops rcu_sync_ops = {
.init = rcu_sync_torture_init,
- .cleanup = NULL,
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay,
.readunlock = rcu_torture_read_unlock,
@@ -493,7 +490,6 @@ static struct rcu_torture_ops rcu_sync_ops = {
static struct rcu_torture_ops rcu_expedited_ops = {
.init = rcu_sync_torture_init,
- .cleanup = NULL,
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_torture_read_unlock,
@@ -536,7 +532,6 @@ static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
static struct rcu_torture_ops rcu_bh_ops = {
.init = NULL,
- .cleanup = NULL,
.readlock = rcu_bh_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_bh_torture_read_unlock,
@@ -553,7 +548,6 @@ static struct rcu_torture_ops rcu_bh_ops = {
static struct rcu_torture_ops rcu_bh_sync_ops = {
.init = rcu_sync_torture_init,
- .cleanup = NULL,
.readlock = rcu_bh_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_bh_torture_read_unlock,
@@ -570,7 +564,6 @@ static struct rcu_torture_ops rcu_bh_sync_ops = {
static struct rcu_torture_ops rcu_bh_expedited_ops = {
.init = rcu_sync_torture_init,
- .cleanup = NULL,
.readlock = rcu_bh_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_bh_torture_read_unlock,
@@ -589,19 +582,7 @@ static struct rcu_torture_ops rcu_bh_expedited_ops = {
* Definitions for srcu torture testing.
*/
-static struct srcu_struct srcu_ctl;
-
-static void srcu_torture_init(void)
-{
- init_srcu_struct(&srcu_ctl);
- rcu_sync_torture_init();
-}
-
-static void srcu_torture_cleanup(void)
-{
- synchronize_srcu(&srcu_ctl);
- cleanup_srcu_struct(&srcu_ctl);
-}
+DEFINE_STATIC_SRCU(srcu_ctl);
static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
{
@@ -672,8 +653,7 @@ static int srcu_torture_stats(char *page)
}
static struct rcu_torture_ops srcu_ops = {
- .init = srcu_torture_init,
- .cleanup = srcu_torture_cleanup,
+ .init = rcu_sync_torture_init,
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
@@ -687,8 +667,7 @@ static struct rcu_torture_ops srcu_ops = {
};
static struct rcu_torture_ops srcu_sync_ops = {
- .init = srcu_torture_init,
- .cleanup = srcu_torture_cleanup,
+ .init = rcu_sync_torture_init,
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
@@ -712,8 +691,7 @@ static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
}
static struct rcu_torture_ops srcu_raw_ops = {
- .init = srcu_torture_init,
- .cleanup = srcu_torture_cleanup,
+ .init = rcu_sync_torture_init,
.readlock = srcu_torture_read_lock_raw,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock_raw,
@@ -727,8 +705,7 @@ static struct rcu_torture_ops srcu_raw_ops = {
};
static struct rcu_torture_ops srcu_raw_sync_ops = {
- .init = srcu_torture_init,
- .cleanup = srcu_torture_cleanup,
+ .init = rcu_sync_torture_init,
.readlock = srcu_torture_read_lock_raw,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock_raw,
@@ -747,8 +724,7 @@ static void srcu_torture_synchronize_expedited(void)
}
static struct rcu_torture_ops srcu_expedited_ops = {
- .init = srcu_torture_init,
- .cleanup = srcu_torture_cleanup,
+ .init = rcu_sync_torture_init,
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
@@ -783,7 +759,6 @@ static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
static struct rcu_torture_ops sched_ops = {
.init = rcu_sync_torture_init,
- .cleanup = NULL,
.readlock = sched_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = sched_torture_read_unlock,
@@ -799,7 +774,6 @@ static struct rcu_torture_ops sched_ops = {
static struct rcu_torture_ops sched_sync_ops = {
.init = rcu_sync_torture_init,
- .cleanup = NULL,
.readlock = sched_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = sched_torture_read_unlock,
@@ -814,7 +788,6 @@ static struct rcu_torture_ops sched_sync_ops = {
static struct rcu_torture_ops sched_expedited_ops = {
.init = rcu_sync_torture_init,
- .cleanup = NULL,
.readlock = sched_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = sched_torture_read_unlock,
@@ -1396,12 +1369,16 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
"test_boost=%d/%d test_boost_interval=%d "
"test_boost_duration=%d shutdown_secs=%d "
+ "stall_cpu=%d stall_cpu_holdoff=%d "
+ "n_barrier_cbs=%d "
"onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
test_boost, cur_ops->can_boost,
test_boost_interval, test_boost_duration, shutdown_secs,
+ stall_cpu, stall_cpu_holdoff,
+ n_barrier_cbs,
onoff_interval, onoff_holdoff);
}
@@ -1502,6 +1479,7 @@ rcu_torture_onoff(void *arg)
unsigned long delta;
int maxcpu = -1;
DEFINE_RCU_RANDOM(rand);
+ int ret;
unsigned long starttime;
VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
@@ -1522,7 +1500,13 @@ rcu_torture_onoff(void *arg)
torture_type, cpu);
starttime = jiffies;
n_offline_attempts++;
- if (cpu_down(cpu) == 0) {
+ ret = cpu_down(cpu);
+ if (ret) {
+ if (verbose)
+ pr_alert("%s" TORTURE_FLAG
+ "rcu_torture_onoff task: offline %d failed: errno %d\n",
+ torture_type, cpu, ret);
+ } else {
if (verbose)
pr_alert("%s" TORTURE_FLAG
"rcu_torture_onoff task: offlined %d\n",
@@ -1936,8 +1920,6 @@ rcu_torture_cleanup(void)
rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
- if (cur_ops->cleanup)
- cur_ops->cleanup();
if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
else if (n_online_successes != n_online_attempts ||
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 74df86bd920..e441b77b614 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -68,9 +68,9 @@ static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS];
.level = { &sname##_state.node[0] }, \
.call = cr, \
.fqs_state = RCU_GP_IDLE, \
- .gpnum = -300, \
- .completed = -300, \
- .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.onofflock), \
+ .gpnum = 0UL - 300UL, \
+ .completed = 0UL - 300UL, \
+ .orphan_lock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.orphan_lock), \
.orphan_nxttail = &sname##_state.orphan_nxtlist, \
.orphan_donetail = &sname##_state.orphan_donelist, \
.barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \
@@ -207,18 +207,15 @@ EXPORT_SYMBOL_GPL(rcu_note_context_switch);
DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
.dynticks_nesting = DYNTICK_TASK_EXIT_IDLE,
.dynticks = ATOMIC_INIT(1),
-#if defined(CONFIG_RCU_USER_QS) && !defined(CONFIG_RCU_USER_QS_FORCE)
- .ignore_user_qs = true,
-#endif
};
-static int blimit = 10; /* Maximum callbacks per rcu_do_batch. */
-static int qhimark = 10000; /* If this many pending, ignore blimit. */
-static int qlowmark = 100; /* Once only this many pending, use blimit. */
+static long blimit = 10; /* Maximum callbacks per rcu_do_batch. */
+static long qhimark = 10000; /* If this many pending, ignore blimit. */
+static long qlowmark = 100; /* Once only this many pending, use blimit. */
-module_param(blimit, int, 0444);
-module_param(qhimark, int, 0444);
-module_param(qlowmark, int, 0444);
+module_param(blimit, long, 0444);
+module_param(qhimark, long, 0444);
+module_param(qlowmark, long, 0444);
int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
@@ -303,7 +300,8 @@ EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
static int
cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp)
{
- return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL];
+ return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL] &&
+ rdp->nxttail[RCU_DONE_TAIL] != NULL;
}
/*
@@ -312,8 +310,11 @@ cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp)
static int
cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
{
- return *rdp->nxttail[RCU_DONE_TAIL +
- ACCESS_ONCE(rsp->completed) != rdp->completed] &&
+ struct rcu_head **ntp;
+
+ ntp = rdp->nxttail[RCU_DONE_TAIL +
+ (ACCESS_ONCE(rsp->completed) != rdp->completed)];
+ return rdp->nxttail[RCU_DONE_TAIL] && ntp && *ntp &&
!rcu_gp_in_progress(rsp);
}
@@ -416,29 +417,7 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
*/
void rcu_user_enter(void)
{
- unsigned long flags;
- struct rcu_dynticks *rdtp;
-
- /*
- * Some contexts may involve an exception occuring in an irq,
- * leading to that nesting:
- * rcu_irq_enter() rcu_user_exit() rcu_user_exit() rcu_irq_exit()
- * This would mess up the dyntick_nesting count though. And rcu_irq_*()
- * helpers are enough to protect RCU uses inside the exception. So
- * just return immediately if we detect we are in an IRQ.
- */
- if (in_interrupt())
- return;
-
- WARN_ON_ONCE(!current->mm);
-
- local_irq_save(flags);
- rdtp = &__get_cpu_var(rcu_dynticks);
- if (!rdtp->ignore_user_qs && !rdtp->in_user) {
- rdtp->in_user = true;
- rcu_eqs_enter(true);
- }
- local_irq_restore(flags);
+ rcu_eqs_enter(1);
}
/**
@@ -575,27 +554,7 @@ EXPORT_SYMBOL_GPL(rcu_idle_exit);
*/
void rcu_user_exit(void)
{
- unsigned long flags;
- struct rcu_dynticks *rdtp;
-
- /*
- * Some contexts may involve an exception occuring in an irq,
- * leading to that nesting:
- * rcu_irq_enter() rcu_user_exit() rcu_user_exit() rcu_irq_exit()
- * This would mess up the dyntick_nesting count though. And rcu_irq_*()
- * helpers are enough to protect RCU uses inside the exception. So
- * just return immediately if we detect we are in an IRQ.
- */
- if (in_interrupt())
- return;
-
- local_irq_save(flags);
- rdtp = &__get_cpu_var(rcu_dynticks);
- if (rdtp->in_user) {
- rdtp->in_user = false;
- rcu_eqs_exit(true);
- }
- local_irq_restore(flags);
+ rcu_eqs_exit(1);
}
/**
@@ -718,21 +677,6 @@ int rcu_is_cpu_idle(void)
}
EXPORT_SYMBOL(rcu_is_cpu_idle);
-#ifdef CONFIG_RCU_USER_QS
-void rcu_user_hooks_switch(struct task_struct *prev,
- struct task_struct *next)
-{
- struct rcu_dynticks *rdtp;
-
- /* Interrupts are disabled in context switch */
- rdtp = &__get_cpu_var(rcu_dynticks);
- if (!rdtp->ignore_user_qs) {
- clear_tsk_thread_flag(prev, TIF_NOHZ);
- set_tsk_thread_flag(next, TIF_NOHZ);
- }
-}
-#endif /* #ifdef CONFIG_RCU_USER_QS */
-
#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU)
/*
@@ -873,6 +817,29 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
rsp->jiffies_stall = jiffies + jiffies_till_stall_check();
}
+/*
+ * Dump stacks of all tasks running on stalled CPUs. This is a fallback
+ * for architectures that do not implement trigger_all_cpu_backtrace().
+ * The NMI-triggered stack traces are more accurate because they are
+ * printed by the target CPU.
+ */
+static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
+{
+ int cpu;
+ unsigned long flags;
+ struct rcu_node *rnp;
+
+ rcu_for_each_leaf_node(rsp, rnp) {
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ if (rnp->qsmask != 0) {
+ for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
+ if (rnp->qsmask & (1UL << cpu))
+ dump_cpu_task(rnp->grplo + cpu);
+ }
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ }
+}
+
static void print_other_cpu_stall(struct rcu_state *rsp)
{
int cpu;
@@ -880,6 +847,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
unsigned long flags;
int ndetected = 0;
struct rcu_node *rnp = rcu_get_root(rsp);
+ long totqlen = 0;
/* Only let one CPU complain about others per time interval. */
@@ -924,12 +892,15 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
raw_spin_unlock_irqrestore(&rnp->lock, flags);
print_cpu_stall_info_end();
- printk(KERN_CONT "(detected by %d, t=%ld jiffies)\n",
- smp_processor_id(), (long)(jiffies - rsp->gp_start));
+ for_each_possible_cpu(cpu)
+ totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen;
+ pr_cont("(detected by %d, t=%ld jiffies, g=%lu, c=%lu, q=%lu)\n",
+ smp_processor_id(), (long)(jiffies - rsp->gp_start),
+ rsp->gpnum, rsp->completed, totqlen);
if (ndetected == 0)
printk(KERN_ERR "INFO: Stall ended before state dump start\n");
else if (!trigger_all_cpu_backtrace())
- dump_stack();
+ rcu_dump_cpu_stacks(rsp);
/* Complain about tasks blocking the grace period. */
@@ -940,8 +911,10 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
static void print_cpu_stall(struct rcu_state *rsp)
{
+ int cpu;
unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp);
+ long totqlen = 0;
/*
* OK, time to rat on ourselves...
@@ -952,7 +925,10 @@ static void print_cpu_stall(struct rcu_state *rsp)
print_cpu_stall_info_begin();
print_cpu_stall_info(rsp, smp_processor_id());
print_cpu_stall_info_end();
- printk(KERN_CONT " (t=%lu jiffies)\n", jiffies - rsp->gp_start);
+ for_each_possible_cpu(cpu)
+ totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen;
+ pr_cont(" (t=%lu jiffies g=%lu c=%lu q=%lu)\n",
+ jiffies - rsp->gp_start, rsp->gpnum, rsp->completed, totqlen);
if (!trigger_all_cpu_backtrace())
dump_stack();
@@ -1091,6 +1067,7 @@ static void init_callback_list(struct rcu_data *rdp)
rdp->nxtlist = NULL;
for (i = 0; i < RCU_NEXT_SIZE; i++)
rdp->nxttail[i] = &rdp->nxtlist;
+ init_nocb_callback_list(rdp);
}
/*
@@ -1404,15 +1381,37 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
!cpu_needs_another_gp(rsp, rdp)) {
/*
* Either we have not yet spawned the grace-period
- * task or this CPU does not need another grace period.
+ * task, this CPU does not need another grace period,
+ * or a grace period is already in progress.
* Either way, don't start a new grace period.
*/
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
+ /*
+ * Because there is no grace period in progress right now,
+ * any callbacks we have up to this point will be satisfied
+ * by the next grace period. So promote all callbacks to be
+ * handled after the end of the next grace period. If the
+ * CPU is not yet aware of the end of the previous grace period,
+ * we need to allow for the callback advancement that will
+ * occur when it does become aware. Deadlock prevents us from
+ * making it aware at this point: We cannot acquire a leaf
+ * rcu_node ->lock while holding the root rcu_node ->lock.
+ */
+ rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+ if (rdp->completed == rsp->completed)
+ rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+
rsp->gp_flags = RCU_GP_FLAG_INIT;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */
+
+ /* Ensure that CPU is aware of completion of last grace period. */
+ rcu_process_gp_end(rsp, rdp);
+ local_irq_restore(flags);
+
+ /* Wake up rcu_gp_kthread() to start the grace period. */
wake_up(&rsp->gp_wq);
}
@@ -1573,16 +1572,20 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
/*
* Send the specified CPU's RCU callbacks to the orphanage. The
* specified CPU must be offline, and the caller must hold the
- * ->onofflock.
+ * ->orphan_lock.
*/
static void
rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
struct rcu_node *rnp, struct rcu_data *rdp)
{
+ /* No-CBs CPUs do not have orphanable callbacks. */
+ if (is_nocb_cpu(rdp->cpu))
+ return;
+
/*
* Orphan the callbacks. First adjust the counts. This is safe
- * because ->onofflock excludes _rcu_barrier()'s adoption of
- * the callbacks, thus no memory barrier is required.
+ * because _rcu_barrier() excludes CPU-hotplug operations, so it
+ * cannot be running now. Thus no memory barrier is required.
*/
if (rdp->nxtlist != NULL) {
rsp->qlen_lazy += rdp->qlen_lazy;
@@ -1623,13 +1626,17 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
/*
* Adopt the RCU callbacks from the specified rcu_state structure's
- * orphanage. The caller must hold the ->onofflock.
+ * orphanage. The caller must hold the ->orphan_lock.
*/
static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
{
int i;
struct rcu_data *rdp = __this_cpu_ptr(rsp->rda);
+ /* No-CBs CPUs are handled specially. */
+ if (rcu_nocb_adopt_orphan_cbs(rsp, rdp))
+ return;
+
/* Do the accounting first. */
rdp->qlen_lazy += rsp->qlen_lazy;
rdp->qlen += rsp->qlen;
@@ -1702,7 +1709,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
/* Exclude any attempts to start a new grace period. */
mutex_lock(&rsp->onoff_mutex);
- raw_spin_lock_irqsave(&rsp->onofflock, flags);
+ raw_spin_lock_irqsave(&rsp->orphan_lock, flags);
/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */
rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);
@@ -1729,10 +1736,10 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
/*
* We still hold the leaf rcu_node structure lock here, and
* irqs are still disabled. The reason for this subterfuge is
- * because invoking rcu_report_unblock_qs_rnp() with ->onofflock
+ * because invoking rcu_report_unblock_qs_rnp() with ->orphan_lock
* held leads to deadlock.
*/
- raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
+ raw_spin_unlock(&rsp->orphan_lock); /* irqs remain disabled. */
rnp = rdp->mynode;
if (need_report & RCU_OFL_TASKS_NORM_GP)
rcu_report_unblock_qs_rnp(rnp, flags);
@@ -1769,7 +1776,8 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
{
unsigned long flags;
struct rcu_head *next, *list, **tail;
- int bl, count, count_lazy, i;
+ long bl, count, count_lazy;
+ int i;
/* If no callbacks are ready, just return.*/
if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
@@ -2107,9 +2115,15 @@ static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp,
}
}
+/*
+ * Helper function for call_rcu() and friends. The cpu argument will
+ * normally be -1, indicating "currently running CPU". It may specify
+ * a CPU only if that CPU is a no-CBs CPU. Currently, only _rcu_barrier()
+ * is expected to specify a CPU.
+ */
static void
__call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
- struct rcu_state *rsp, bool lazy)
+ struct rcu_state *rsp, int cpu, bool lazy)
{
unsigned long flags;
struct rcu_data *rdp;
@@ -2129,9 +2143,14 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
rdp = this_cpu_ptr(rsp->rda);
/* Add the callback to our list. */
- if (unlikely(rdp->nxttail[RCU_NEXT_TAIL] == NULL)) {
+ if (unlikely(rdp->nxttail[RCU_NEXT_TAIL] == NULL) || cpu != -1) {
+ int offline;
+
+ if (cpu != -1)
+ rdp = per_cpu_ptr(rsp->rda, cpu);
+ offline = !__call_rcu_nocb(rdp, head, lazy);
+ WARN_ON_ONCE(offline);
/* _call_rcu() is illegal on offline CPU; leak the callback. */
- WARN_ON_ONCE(1);
local_irq_restore(flags);
return;
}
@@ -2160,7 +2179,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
*/
void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
{
- __call_rcu(head, func, &rcu_sched_state, 0);
+ __call_rcu(head, func, &rcu_sched_state, -1, 0);
}
EXPORT_SYMBOL_GPL(call_rcu_sched);
@@ -2169,7 +2188,7 @@ EXPORT_SYMBOL_GPL(call_rcu_sched);
*/
void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
{
- __call_rcu(head, func, &rcu_bh_state, 0);
+ __call_rcu(head, func, &rcu_bh_state, -1, 0);
}
EXPORT_SYMBOL_GPL(call_rcu_bh);
@@ -2205,10 +2224,28 @@ static inline int rcu_blocking_is_gp(void)
* rcu_read_lock_sched().
*
* This means that all preempt_disable code sequences, including NMI and
- * hardware-interrupt handlers, in progress on entry will have completed
- * before this primitive returns. However, this does not guarantee that
- * softirq handlers will have completed, since in some kernels, these
- * handlers can run in process context, and can block.
+ * non-threaded hardware-interrupt handlers, in progress on entry will
+ * have completed before this primitive returns. However, this does not
+ * guarantee that softirq handlers will have completed, since in some
+ * kernels, these handlers can run in process context, and can block.
+ *
+ * Note that this guarantee implies further memory-ordering guarantees.
+ * On systems with more than one CPU, when synchronize_sched() returns,
+ * each CPU is guaranteed to have executed a full memory barrier since the
+ * end of its last RCU-sched read-side critical section whose beginning
+ * preceded the call to synchronize_sched(). In addition, each CPU having
+ * an RCU read-side critical section that extends beyond the return from
+ * synchronize_sched() is guaranteed to have executed a full memory barrier
+ * after the beginning of synchronize_sched() and before the beginning of
+ * that RCU read-side critical section. Note that these guarantees include
+ * CPUs that are offline, idle, or executing in user mode, as well as CPUs
+ * that are executing in the kernel.
+ *
+ * Furthermore, if CPU A invoked synchronize_sched(), which returned
+ * to its caller on CPU B, then both CPU A and CPU B are guaranteed
+ * to have executed a full memory barrier during the execution of
+ * synchronize_sched() -- even if CPU A and CPU B are the same CPU (but
+ * again only if the system has more than one CPU).
*
* This primitive provides the guarantees made by the (now removed)
* synchronize_kernel() API. In contrast, synchronize_rcu() only
@@ -2224,7 +2261,10 @@ void synchronize_sched(void)
"Illegal synchronize_sched() in RCU-sched read-side critical section");
if (rcu_blocking_is_gp())
return;
- wait_rcu_gp(call_rcu_sched);
+ if (rcu_expedited)
+ synchronize_sched_expedited();
+ else
+ wait_rcu_gp(call_rcu_sched);
}
EXPORT_SYMBOL_GPL(synchronize_sched);
@@ -2236,6 +2276,9 @@ EXPORT_SYMBOL_GPL(synchronize_sched);
* read-side critical sections have completed. RCU read-side critical
* sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
* and may be nested.
+ *
+ * See the description of synchronize_sched() for more detailed information
+ * on memory ordering guarantees.
*/
void synchronize_rcu_bh(void)
{
@@ -2245,13 +2288,13 @@ void synchronize_rcu_bh(void)
"Illegal synchronize_rcu_bh() in RCU-bh read-side critical section");
if (rcu_blocking_is_gp())
return;
- wait_rcu_gp(call_rcu_bh);
+ if (rcu_expedited)
+ synchronize_rcu_bh_expedited();
+ else
+ wait_rcu_gp(call_rcu_bh);
}
EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
-static atomic_t sync_sched_expedited_started = ATOMIC_INIT(0);
-static atomic_t sync_sched_expedited_done = ATOMIC_INIT(0);
-
static int synchronize_sched_expedited_cpu_stop(void *data)
{
/*
@@ -2308,10 +2351,32 @@ static int synchronize_sched_expedited_cpu_stop(void *data)
*/
void synchronize_sched_expedited(void)
{
- int firstsnap, s, snap, trycount = 0;
+ long firstsnap, s, snap;
+ int trycount = 0;
+ struct rcu_state *rsp = &rcu_sched_state;
+
+ /*
+ * If we are in danger of counter wrap, just do synchronize_sched().
+ * By allowing sync_sched_expedited_started to advance no more than
+ * ULONG_MAX/8 ahead of sync_sched_expedited_done, we are ensuring
+ * that more than 3.5 billion CPUs would be required to force a
+ * counter wrap on a 32-bit system. Quite a few more CPUs would of
+ * course be required on a 64-bit system.
+ */
+ if (ULONG_CMP_GE((ulong)atomic_long_read(&rsp->expedited_start),
+ (ulong)atomic_long_read(&rsp->expedited_done) +
+ ULONG_MAX / 8)) {
+ synchronize_sched();
+ atomic_long_inc(&rsp->expedited_wrap);
+ return;
+ }
- /* Note that atomic_inc_return() implies full memory barrier. */
- firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started);
+ /*
+ * Take a ticket. Note that atomic_inc_return() implies a
+ * full memory barrier.
+ */
+ snap = atomic_long_inc_return(&rsp->expedited_start);
+ firstsnap = snap;
get_online_cpus();
WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id()));
@@ -2323,48 +2388,65 @@ void synchronize_sched_expedited(void)
synchronize_sched_expedited_cpu_stop,
NULL) == -EAGAIN) {
put_online_cpus();
+ atomic_long_inc(&rsp->expedited_tryfail);
+
+ /* Check to see if someone else did our work for us. */
+ s = atomic_long_read(&rsp->expedited_done);
+ if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {
+ /* ensure test happens before caller kfree */
+ smp_mb__before_atomic_inc(); /* ^^^ */
+ atomic_long_inc(&rsp->expedited_workdone1);
+ return;
+ }
/* No joy, try again later. Or just synchronize_sched(). */
if (trycount++ < 10) {
udelay(trycount * num_online_cpus());
} else {
- synchronize_sched();
+ wait_rcu_gp(call_rcu_sched);
+ atomic_long_inc(&rsp->expedited_normal);
return;
}
- /* Check to see if someone else did our work for us. */
- s = atomic_read(&sync_sched_expedited_done);
- if (UINT_CMP_GE((unsigned)s, (unsigned)firstsnap)) {
- smp_mb(); /* ensure test happens before caller kfree */
+ /* Recheck to see if someone else did our work for us. */
+ s = atomic_long_read(&rsp->expedited_done);
+ if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {
+ /* ensure test happens before caller kfree */
+ smp_mb__before_atomic_inc(); /* ^^^ */
+ atomic_long_inc(&rsp->expedited_workdone2);
return;
}
/*
* Refetching sync_sched_expedited_started allows later
- * callers to piggyback on our grace period. We subtract
- * 1 to get the same token that the last incrementer got.
- * We retry after they started, so our grace period works
- * for them, and they started after our first try, so their
- * grace period works for us.
+ * callers to piggyback on our grace period. We retry
+ * after they started, so our grace period works for them,
+ * and they started after our first try, so their grace
+ * period works for us.
*/
get_online_cpus();
- snap = atomic_read(&sync_sched_expedited_started);
+ snap = atomic_long_read(&rsp->expedited_start);
smp_mb(); /* ensure read is before try_stop_cpus(). */
}
+ atomic_long_inc(&rsp->expedited_stoppedcpus);
/*
* Everyone up to our most recent fetch is covered by our grace
* period. Update the counter, but only if our work is still
* relevant -- which it won't be if someone who started later
- * than we did beat us to the punch.
+ * than we did already did their update.
*/
do {
- s = atomic_read(&sync_sched_expedited_done);
- if (UINT_CMP_GE((unsigned)s, (unsigned)snap)) {
- smp_mb(); /* ensure test happens before caller kfree */
+ atomic_long_inc(&rsp->expedited_done_tries);
+ s = atomic_long_read(&rsp->expedited_done);
+ if (ULONG_CMP_GE((ulong)s, (ulong)snap)) {
+ /* ensure test happens before caller kfree */
+ smp_mb__before_atomic_inc(); /* ^^^ */
+ atomic_long_inc(&rsp->expedited_done_lost);
break;
}
- } while (atomic_cmpxchg(&sync_sched_expedited_done, s, snap) != s);
+ } while (atomic_long_cmpxchg(&rsp->expedited_done, s, snap) != s);
+ atomic_long_inc(&rsp->expedited_done_exit);
put_online_cpus();
}
@@ -2558,9 +2640,17 @@ static void _rcu_barrier(struct rcu_state *rsp)
* When that callback is invoked, we will know that all of the
* corresponding CPU's preceding callbacks have been invoked.
*/
- for_each_online_cpu(cpu) {
+ for_each_possible_cpu(cpu) {
+ if (!cpu_online(cpu) && !is_nocb_cpu(cpu))
+ continue;
rdp = per_cpu_ptr(rsp->rda, cpu);
- if (ACCESS_ONCE(rdp->qlen)) {
+ if (is_nocb_cpu(cpu)) {
+ _rcu_barrier_trace(rsp, "OnlineNoCB", cpu,
+ rsp->n_barrier_done);
+ atomic_inc(&rsp->barrier_cpu_count);
+ __call_rcu(&rdp->barrier_head, rcu_barrier_callback,
+ rsp, cpu, 0);
+ } else if (ACCESS_ONCE(rdp->qlen)) {
_rcu_barrier_trace(rsp, "OnlineQ", cpu,
rsp->n_barrier_done);
smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
@@ -2634,6 +2724,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
#endif
rdp->cpu = cpu;
rdp->rsp = rsp;
+ rcu_boot_init_nocb_percpu_data(rdp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
@@ -2715,6 +2806,7 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
struct rcu_node *rnp = rdp->mynode;
struct rcu_state *rsp;
+ int ret = NOTIFY_OK;
trace_rcu_utilization("Start CPU hotplug");
switch (action) {
@@ -2728,7 +2820,10 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
rcu_boost_kthread_setaffinity(rnp, -1);
break;
case CPU_DOWN_PREPARE:
- rcu_boost_kthread_setaffinity(rnp, cpu);
+ if (nocb_cpu_expendable(cpu))
+ rcu_boost_kthread_setaffinity(rnp, cpu);
+ else
+ ret = NOTIFY_BAD;
break;
case CPU_DYING:
case CPU_DYING_FROZEN:
@@ -2752,7 +2847,7 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
break;
}
trace_rcu_utilization("End CPU hotplug");
- return NOTIFY_OK;
+ return ret;
}
/*
@@ -2772,6 +2867,7 @@ static int __init rcu_spawn_gp_kthread(void)
raw_spin_lock_irqsave(&rnp->lock, flags);
rsp->gp_kthread = t;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ rcu_spawn_nocb_kthreads(rsp);
}
return 0;
}
@@ -2967,6 +3063,7 @@ void __init rcu_init(void)
rcu_init_one(&rcu_sched_state, &rcu_sched_data);
rcu_init_one(&rcu_bh_state, &rcu_bh_data);
__rcu_init_preempt();
+ rcu_init_nocb();
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
/*
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index a240f032848..4b69291b093 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -287,6 +287,7 @@ struct rcu_data {
long qlen_last_fqs_check;
/* qlen at last check for QS forcing */
unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */
+ unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */
unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */
unsigned long n_force_qs_snap;
@@ -317,6 +318,18 @@ struct rcu_data {
struct rcu_head oom_head;
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
+ /* 7) Callback offloading. */
+#ifdef CONFIG_RCU_NOCB_CPU
+ struct rcu_head *nocb_head; /* CBs waiting for kthread. */
+ struct rcu_head **nocb_tail;
+ atomic_long_t nocb_q_count; /* # CBs waiting for kthread */
+ atomic_long_t nocb_q_count_lazy; /* (approximate). */
+ int nocb_p_count; /* # CBs being invoked by kthread */
+ int nocb_p_count_lazy; /* (approximate). */
+ wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */
+ struct task_struct *nocb_kthread;
+#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
+
int cpu;
struct rcu_state *rsp;
};
@@ -369,6 +382,12 @@ struct rcu_state {
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
void (*func)(struct rcu_head *head));
+#ifdef CONFIG_RCU_NOCB_CPU
+ void (*call_remote)(struct rcu_head *head,
+ void (*func)(struct rcu_head *head));
+ /* call_rcu() flavor, but for */
+ /* placing on remote CPU. */
+#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
/* The following fields are guarded by the root rcu_node's lock. */
@@ -383,9 +402,8 @@ struct rcu_state {
/* End of fields guarded by root rcu_node's lock. */
- raw_spinlock_t onofflock ____cacheline_internodealigned_in_smp;
- /* exclude on/offline and */
- /* starting new GP. */
+ raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
+ /* Protect following fields. */
struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
/* need a grace period. */
struct rcu_head **orphan_nxttail; /* Tail of above. */
@@ -394,7 +412,7 @@ struct rcu_state {
struct rcu_head **orphan_donetail; /* Tail of above. */
long qlen_lazy; /* Number of lazy callbacks. */
long qlen; /* Total number of callbacks. */
- /* End of fields guarded by onofflock. */
+ /* End of fields guarded by orphan_lock. */
struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */
@@ -405,6 +423,18 @@ struct rcu_state {
/* _rcu_barrier(). */
/* End of fields guarded by barrier_mutex. */
+ atomic_long_t expedited_start; /* Starting ticket. */
+ atomic_long_t expedited_done; /* Done ticket. */
+ atomic_long_t expedited_wrap; /* # near-wrap incidents. */
+ atomic_long_t expedited_tryfail; /* # acquisition failures. */
+ atomic_long_t expedited_workdone1; /* # done by others #1. */
+ atomic_long_t expedited_workdone2; /* # done by others #2. */
+ atomic_long_t expedited_normal; /* # fallbacks to normal. */
+ atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */
+ atomic_long_t expedited_done_tries; /* # tries to update _done. */
+ atomic_long_t expedited_done_lost; /* # times beaten to _done. */
+ atomic_long_t expedited_done_exit; /* # times exited _done loop. */
+
unsigned long jiffies_force_qs; /* Time at which to invoke */
/* force_quiescent_state(). */
unsigned long n_force_qs; /* Number of calls to */
@@ -428,6 +458,8 @@ struct rcu_state {
#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
extern struct list_head rcu_struct_flavors;
+
+/* Sequence through rcu_state structures for each RCU flavor. */
#define for_each_rcu_flavor(rsp) \
list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
@@ -504,5 +536,32 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
static void print_cpu_stall_info_end(void);
static void zero_cpu_stall_ticks(struct rcu_data *rdp);
static void increment_cpu_stall_ticks(void);
+static bool is_nocb_cpu(int cpu);
+static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
+ bool lazy);
+static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
+ struct rcu_data *rdp);
+static bool nocb_cpu_expendable(int cpu);
+static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
+static void rcu_spawn_nocb_kthreads(struct rcu_state *rsp);
+static void init_nocb_callback_list(struct rcu_data *rdp);
+static void __init rcu_init_nocb(void);
#endif /* #ifndef RCU_TREE_NONCORE */
+
+#ifdef CONFIG_RCU_TRACE
+#ifdef CONFIG_RCU_NOCB_CPU
+/* Sum up queue lengths for tracing. */
+static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
+{
+ *ql = atomic_long_read(&rdp->nocb_q_count) + rdp->nocb_p_count;
+ *qll = atomic_long_read(&rdp->nocb_q_count_lazy) + rdp->nocb_p_count_lazy;
+}
+#else /* #ifdef CONFIG_RCU_NOCB_CPU */
+static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
+{
+ *ql = 0;
+ *qll = 0;
+}
+#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
+#endif /* #ifdef CONFIG_RCU_TRACE */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index f9211548818..f6e5ec2932b 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -25,6 +25,7 @@
*/
#include <linux/delay.h>
+#include <linux/gfp.h>
#include <linux/oom.h>
#include <linux/smpboot.h>
@@ -36,6 +37,14 @@
#define RCU_BOOST_PRIO RCU_KTHREAD_PRIO
#endif
+#ifdef CONFIG_RCU_NOCB_CPU
+static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
+static bool have_rcu_nocb_mask; /* Was rcu_nocb_mask allocated? */
+static bool rcu_nocb_poll; /* Offload kthread are to poll. */
+module_param(rcu_nocb_poll, bool, 0444);
+static char __initdata nocb_buf[NR_CPUS * 5];
+#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
+
/*
* Check the RCU kernel configuration parameters and print informative
* messages about anything out of the ordinary. If you like #ifdef, you
@@ -76,6 +85,18 @@ static void __init rcu_bootup_announce_oddness(void)
printk(KERN_INFO "\tExperimental boot-time adjustment of leaf fanout to %d.\n", rcu_fanout_leaf);
if (nr_cpu_ids != NR_CPUS)
printk(KERN_INFO "\tRCU restricting CPUs from NR_CPUS=%d to nr_cpu_ids=%d.\n", NR_CPUS, nr_cpu_ids);
+#ifdef CONFIG_RCU_NOCB_CPU
+ if (have_rcu_nocb_mask) {
+ if (cpumask_test_cpu(0, rcu_nocb_mask)) {
+ cpumask_clear_cpu(0, rcu_nocb_mask);
+ pr_info("\tCPU 0: illegal no-CBs CPU (cleared).\n");
+ }
+ cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
+ pr_info("\tExperimental no-CBs CPUs: %s.\n", nocb_buf);
+ if (rcu_nocb_poll)
+ pr_info("\tExperimental polled no-CBs CPUs.\n");
+ }
+#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
}
#ifdef CONFIG_TREE_PREEMPT_RCU
@@ -642,7 +663,7 @@ static void rcu_preempt_do_callbacks(void)
*/
void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
{
- __call_rcu(head, func, &rcu_preempt_state, 0);
+ __call_rcu(head, func, &rcu_preempt_state, -1, 0);
}
EXPORT_SYMBOL_GPL(call_rcu);
@@ -656,7 +677,7 @@ EXPORT_SYMBOL_GPL(call_rcu);
void kfree_call_rcu(struct rcu_head *head,
void (*func)(struct rcu_head *rcu))
{
- __call_rcu(head, func, &rcu_preempt_state, 1);
+ __call_rcu(head, func, &rcu_preempt_state, -1, 1);
}
EXPORT_SYMBOL_GPL(kfree_call_rcu);
@@ -670,6 +691,9 @@ EXPORT_SYMBOL_GPL(kfree_call_rcu);
* concurrently with new RCU read-side critical sections that began while
* synchronize_rcu() was waiting. RCU read-side critical sections are
* delimited by rcu_read_lock() and rcu_read_unlock(), and may be nested.
+ *
+ * See the description of synchronize_sched() for more detailed information
+ * on memory ordering guarantees.
*/
void synchronize_rcu(void)
{
@@ -679,7 +703,10 @@ void synchronize_rcu(void)
"Illegal synchronize_rcu() in RCU read-side critical section");
if (!rcu_scheduler_active)
return;
- wait_rcu_gp(call_rcu);
+ if (rcu_expedited)
+ synchronize_rcu_expedited();
+ else
+ wait_rcu_gp(call_rcu);
}
EXPORT_SYMBOL_GPL(synchronize_rcu);
@@ -757,7 +784,8 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
* grace period for the specified rcu_node structure. If there are no such
* tasks, report it up the rcu_node hierarchy.
*
- * Caller must hold sync_rcu_preempt_exp_mutex and rsp->onofflock.
+ * Caller must hold sync_rcu_preempt_exp_mutex and must exclude
+ * CPU hotplug operations.
*/
static void
sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp)
@@ -831,7 +859,7 @@ void synchronize_rcu_expedited(void)
udelay(trycount * num_online_cpus());
} else {
put_online_cpus();
- synchronize_rcu();
+ wait_rcu_gp(call_rcu);
return;
}
}
@@ -875,6 +903,11 @@ EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
/**
* rcu_barrier - Wait until all in-flight call_rcu() callbacks complete.
+ *
+ * Note that this primitive does not necessarily wait for an RCU grace period
+ * to complete. For example, if there are no RCU callbacks queued anywhere
+ * in the system, then rcu_barrier() is within its rights to return
+ * immediately, without waiting for anything, much less an RCU grace period.
*/
void rcu_barrier(void)
{
@@ -1013,7 +1046,7 @@ static void rcu_preempt_check_callbacks(int cpu)
void kfree_call_rcu(struct rcu_head *head,
void (*func)(struct rcu_head *rcu))
{
- __call_rcu(head, func, &rcu_sched_state, 1);
+ __call_rcu(head, func, &rcu_sched_state, -1, 1);
}
EXPORT_SYMBOL_GPL(kfree_call_rcu);
@@ -2092,3 +2125,373 @@ static void increment_cpu_stall_ticks(void)
}
#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_INFO */
+
+#ifdef CONFIG_RCU_NOCB_CPU
+
+/*
+ * Offload callback processing from the boot-time-specified set of CPUs
+ * specified by rcu_nocb_mask. For each CPU in the set, there is a
+ * kthread created that pulls the callbacks from the corresponding CPU,
+ * waits for a grace period to elapse, and invokes the callbacks.
+ * The no-CBs CPUs do a wake_up() on their kthread when they insert
+ * a callback into any empty list, unless the rcu_nocb_poll boot parameter
+ * has been specified, in which case each kthread actively polls its
+ * CPU. (Which isn't so great for energy efficiency, but which does
+ * reduce RCU's overhead on that CPU.)
+ *
+ * This is intended to be used in conjunction with Frederic Weisbecker's
+ * adaptive-idle work, which would seriously reduce OS jitter on CPUs
+ * running CPU-bound user-mode computations.
+ *
+ * Offloading of callback processing could also in theory be used as
+ * an energy-efficiency measure because CPUs with no RCU callbacks
+ * queued are more aggressive about entering dyntick-idle mode.
+ */
+
+
+/* Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters. */
+static int __init rcu_nocb_setup(char *str)
+{
+ alloc_bootmem_cpumask_var(&rcu_nocb_mask);
+ have_rcu_nocb_mask = true;
+ cpulist_parse(str, rcu_nocb_mask);
+ return 1;
+}
+__setup("rcu_nocbs=", rcu_nocb_setup);
+
+/* Is the specified CPU a no-CPUs CPU? */
+static bool is_nocb_cpu(int cpu)
+{
+ if (have_rcu_nocb_mask)
+ return cpumask_test_cpu(cpu, rcu_nocb_mask);
+ return false;
+}
+
+/*
+ * Enqueue the specified string of rcu_head structures onto the specified
+ * CPU's no-CBs lists. The CPU is specified by rdp, the head of the
+ * string by rhp, and the tail of the string by rhtp. The non-lazy/lazy
+ * counts are supplied by rhcount and rhcount_lazy.
+ *
+ * If warranted, also wake up the kthread servicing this CPUs queues.
+ */
+static void __call_rcu_nocb_enqueue(struct rcu_data *rdp,
+ struct rcu_head *rhp,
+ struct rcu_head **rhtp,
+ int rhcount, int rhcount_lazy)
+{
+ int len;
+ struct rcu_head **old_rhpp;
+ struct task_struct *t;
+
+ /* Enqueue the callback on the nocb list and update counts. */
+ old_rhpp = xchg(&rdp->nocb_tail, rhtp);
+ ACCESS_ONCE(*old_rhpp) = rhp;
+ atomic_long_add(rhcount, &rdp->nocb_q_count);
+ atomic_long_add(rhcount_lazy, &rdp->nocb_q_count_lazy);
+
+ /* If we are not being polled and there is a kthread, awaken it ... */
+ t = ACCESS_ONCE(rdp->nocb_kthread);
+ if (rcu_nocb_poll | !t)
+ return;
+ len = atomic_long_read(&rdp->nocb_q_count);
+ if (old_rhpp == &rdp->nocb_head) {
+ wake_up(&rdp->nocb_wq); /* ... only if queue was empty ... */
+ rdp->qlen_last_fqs_check = 0;
+ } else if (len > rdp->qlen_last_fqs_check + qhimark) {
+ wake_up_process(t); /* ... or if many callbacks queued. */
+ rdp->qlen_last_fqs_check = LONG_MAX / 2;
+ }
+ return;
+}
+
+/*
+ * This is a helper for __call_rcu(), which invokes this when the normal
+ * callback queue is inoperable. If this is not a no-CBs CPU, this
+ * function returns failure back to __call_rcu(), which can complain
+ * appropriately.
+ *
+ * Otherwise, this function queues the callback where the corresponding
+ * "rcuo" kthread can find it.
+ */
+static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
+ bool lazy)
+{
+
+ if (!is_nocb_cpu(rdp->cpu))
+ return 0;
+ __call_rcu_nocb_enqueue(rdp, rhp, &rhp->next, 1, lazy);
+ return 1;
+}
+
+/*
+ * Adopt orphaned callbacks on a no-CBs CPU, or return 0 if this is
+ * not a no-CBs CPU.
+ */
+static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
+ struct rcu_data *rdp)
+{
+ long ql = rsp->qlen;
+ long qll = rsp->qlen_lazy;
+
+ /* If this is not a no-CBs CPU, tell the caller to do it the old way. */
+ if (!is_nocb_cpu(smp_processor_id()))
+ return 0;
+ rsp->qlen = 0;
+ rsp->qlen_lazy = 0;
+
+ /* First, enqueue the donelist, if any. This preserves CB ordering. */
+ if (rsp->orphan_donelist != NULL) {
+ __call_rcu_nocb_enqueue(rdp, rsp->orphan_donelist,
+ rsp->orphan_donetail, ql, qll);
+ ql = qll = 0;
+ rsp->orphan_donelist = NULL;
+ rsp->orphan_donetail = &rsp->orphan_donelist;
+ }
+ if (rsp->orphan_nxtlist != NULL) {
+ __call_rcu_nocb_enqueue(rdp, rsp->orphan_nxtlist,
+ rsp->orphan_nxttail, ql, qll);
+ ql = qll = 0;
+ rsp->orphan_nxtlist = NULL;
+ rsp->orphan_nxttail = &rsp->orphan_nxtlist;
+ }
+ return 1;
+}
+
+/*
+ * There must be at least one non-no-CBs CPU in operation at any given
+ * time, because no-CBs CPUs are not capable of initiating grace periods
+ * independently. This function therefore complains if the specified
+ * CPU is the last non-no-CBs CPU, allowing the CPU-hotplug system to
+ * avoid offlining the last such CPU. (Recursion is a wonderful thing,
+ * but you have to have a base case!)
+ */
+static bool nocb_cpu_expendable(int cpu)
+{
+ cpumask_var_t non_nocb_cpus;
+ int ret;
+
+ /*
+ * If there are no no-CB CPUs or if this CPU is not a no-CB CPU,
+ * then offlining this CPU is harmless. Let it happen.
+ */
+ if (!have_rcu_nocb_mask || is_nocb_cpu(cpu))
+ return 1;
+
+ /* If no memory, play it safe and keep the CPU around. */
+ if (!alloc_cpumask_var(&non_nocb_cpus, GFP_NOIO))
+ return 0;
+ cpumask_andnot(non_nocb_cpus, cpu_online_mask, rcu_nocb_mask);
+ cpumask_clear_cpu(cpu, non_nocb_cpus);
+ ret = !cpumask_empty(non_nocb_cpus);
+ free_cpumask_var(non_nocb_cpus);
+ return ret;
+}
+
+/*
+ * Helper structure for remote registry of RCU callbacks.
+ * This is needed for when a no-CBs CPU needs to start a grace period.
+ * If it just invokes call_rcu(), the resulting callback will be queued,
+ * which can result in deadlock.
+ */
+struct rcu_head_remote {
+ struct rcu_head *rhp;
+ call_rcu_func_t *crf;
+ void (*func)(struct rcu_head *rhp);
+};
+
+/*
+ * Register a callback as specified by the rcu_head_remote struct.
+ * This function is intended to be invoked via smp_call_function_single().
+ */
+static void call_rcu_local(void *arg)
+{
+ struct rcu_head_remote *rhrp =
+ container_of(arg, struct rcu_head_remote, rhp);
+
+ rhrp->crf(rhrp->rhp, rhrp->func);
+}
+
+/*
+ * Set up an rcu_head_remote structure and the invoke call_rcu_local()
+ * on CPU 0 (which is guaranteed to be a non-no-CBs CPU) via
+ * smp_call_function_single().
+ */
+static void invoke_crf_remote(struct rcu_head *rhp,
+ void (*func)(struct rcu_head *rhp),
+ call_rcu_func_t crf)
+{
+ struct rcu_head_remote rhr;
+
+ rhr.rhp = rhp;
+ rhr.crf = crf;
+ rhr.func = func;
+ smp_call_function_single(0, call_rcu_local, &rhr, 1);
+}
+
+/*
+ * Helper functions to be passed to wait_rcu_gp(), each of which
+ * invokes invoke_crf_remote() to register a callback appropriately.
+ */
+static void __maybe_unused
+call_rcu_preempt_remote(struct rcu_head *rhp,
+ void (*func)(struct rcu_head *rhp))
+{
+ invoke_crf_remote(rhp, func, call_rcu);
+}
+static void call_rcu_bh_remote(struct rcu_head *rhp,
+ void (*func)(struct rcu_head *rhp))
+{
+ invoke_crf_remote(rhp, func, call_rcu_bh);
+}
+static void call_rcu_sched_remote(struct rcu_head *rhp,
+ void (*func)(struct rcu_head *rhp))
+{
+ invoke_crf_remote(rhp, func, call_rcu_sched);
+}
+
+/*
+ * Per-rcu_data kthread, but only for no-CBs CPUs. Each kthread invokes
+ * callbacks queued by the corresponding no-CBs CPU.
+ */
+static int rcu_nocb_kthread(void *arg)
+{
+ int c, cl;
+ struct rcu_head *list;
+ struct rcu_head *next;
+ struct rcu_head **tail;
+ struct rcu_data *rdp = arg;
+
+ /* Each pass through this loop invokes one batch of callbacks */
+ for (;;) {
+ /* If not polling, wait for next batch of callbacks. */
+ if (!rcu_nocb_poll)
+ wait_event(rdp->nocb_wq, rdp->nocb_head);
+ list = ACCESS_ONCE(rdp->nocb_head);
+ if (!list) {
+ schedule_timeout_interruptible(1);
+ continue;
+ }
+
+ /*
+ * Extract queued callbacks, update counts, and wait
+ * for a grace period to elapse.
+ */
+ ACCESS_ONCE(rdp->nocb_head) = NULL;
+ tail = xchg(&rdp->nocb_tail, &rdp->nocb_head);
+ c = atomic_long_xchg(&rdp->nocb_q_count, 0);
+ cl = atomic_long_xchg(&rdp->nocb_q_count_lazy, 0);
+ ACCESS_ONCE(rdp->nocb_p_count) += c;
+ ACCESS_ONCE(rdp->nocb_p_count_lazy) += cl;
+ wait_rcu_gp(rdp->rsp->call_remote);
+
+ /* Each pass through the following loop invokes a callback. */
+ trace_rcu_batch_start(rdp->rsp->name, cl, c, -1);
+ c = cl = 0;
+ while (list) {
+ next = list->next;
+ /* Wait for enqueuing to complete, if needed. */
+ while (next == NULL && &list->next != tail) {
+ schedule_timeout_interruptible(1);
+ next = list->next;
+ }
+ debug_rcu_head_unqueue(list);
+ local_bh_disable();
+ if (__rcu_reclaim(rdp->rsp->name, list))
+ cl++;
+ c++;
+ local_bh_enable();
+ list = next;
+ }
+ trace_rcu_batch_end(rdp->rsp->name, c, !!list, 0, 0, 1);
+ ACCESS_ONCE(rdp->nocb_p_count) -= c;
+ ACCESS_ONCE(rdp->nocb_p_count_lazy) -= cl;
+ rdp->n_nocbs_invoked += c;
+ }
+ return 0;
+}
+
+/* Initialize per-rcu_data variables for no-CBs CPUs. */
+static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
+{
+ rdp->nocb_tail = &rdp->nocb_head;
+ init_waitqueue_head(&rdp->nocb_wq);
+}
+
+/* Create a kthread for each RCU flavor for each no-CBs CPU. */
+static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp)
+{
+ int cpu;
+ struct rcu_data *rdp;
+ struct task_struct *t;
+
+ if (rcu_nocb_mask == NULL)
+ return;
+ for_each_cpu(cpu, rcu_nocb_mask) {
+ rdp = per_cpu_ptr(rsp->rda, cpu);
+ t = kthread_run(rcu_nocb_kthread, rdp, "rcuo%d", cpu);
+ BUG_ON(IS_ERR(t));
+ ACCESS_ONCE(rdp->nocb_kthread) = t;
+ }
+}
+
+/* Prevent __call_rcu() from enqueuing callbacks on no-CBs CPUs */
+static void init_nocb_callback_list(struct rcu_data *rdp)
+{
+ if (rcu_nocb_mask == NULL ||
+ !cpumask_test_cpu(rdp->cpu, rcu_nocb_mask))
+ return;
+ rdp->nxttail[RCU_NEXT_TAIL] = NULL;
+}
+
+/* Initialize the ->call_remote fields in the rcu_state structures. */
+static void __init rcu_init_nocb(void)
+{
+#ifdef CONFIG_PREEMPT_RCU
+ rcu_preempt_state.call_remote = call_rcu_preempt_remote;
+#endif /* #ifdef CONFIG_PREEMPT_RCU */
+ rcu_bh_state.call_remote = call_rcu_bh_remote;
+ rcu_sched_state.call_remote = call_rcu_sched_remote;
+}
+
+#else /* #ifdef CONFIG_RCU_NOCB_CPU */
+
+static bool is_nocb_cpu(int cpu)
+{
+ return false;
+}
+
+static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
+ bool lazy)
+{
+ return 0;
+}
+
+static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
+ struct rcu_data *rdp)
+{
+ return 0;
+}
+
+static bool nocb_cpu_expendable(int cpu)
+{
+ return 1;
+}
+
+static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
+{
+}
+
+static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp)
+{
+}
+
+static void init_nocb_callback_list(struct rcu_data *rdp)
+{
+}
+
+static void __init rcu_init_nocb(void)
+{
+}
+
+#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 693513bc50e..0d095dcaa67 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -46,29 +46,58 @@
#define RCU_TREE_NONCORE
#include "rcutree.h"
-static int show_rcubarrier(struct seq_file *m, void *unused)
+#define ulong2long(a) (*(long *)(&(a)))
+
+static int r_open(struct inode *inode, struct file *file,
+ const struct seq_operations *op)
{
- struct rcu_state *rsp;
+ int ret = seq_open(file, op);
+ if (!ret) {
+ struct seq_file *m = (struct seq_file *)file->private_data;
+ m->private = inode->i_private;
+ }
+ return ret;
+}
+
+static void *r_start(struct seq_file *m, loff_t *pos)
+{
+ struct rcu_state *rsp = (struct rcu_state *)m->private;
+ *pos = cpumask_next(*pos - 1, cpu_possible_mask);
+ if ((*pos) < nr_cpu_ids)
+ return per_cpu_ptr(rsp->rda, *pos);
+ return NULL;
+}
- for_each_rcu_flavor(rsp)
- seq_printf(m, "%s: bcc: %d nbd: %lu\n",
- rsp->name,
- atomic_read(&rsp->barrier_cpu_count),
- rsp->n_barrier_done);
+static void *r_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ (*pos)++;
+ return r_start(m, pos);
+}
+
+static void r_stop(struct seq_file *m, void *v)
+{
+}
+
+static int show_rcubarrier(struct seq_file *m, void *v)
+{
+ struct rcu_state *rsp = (struct rcu_state *)m->private;
+ seq_printf(m, "bcc: %d nbd: %lu\n",
+ atomic_read(&rsp->barrier_cpu_count),
+ rsp->n_barrier_done);
return 0;
}
static int rcubarrier_open(struct inode *inode, struct file *file)
{
- return single_open(file, show_rcubarrier, NULL);
+ return single_open(file, show_rcubarrier, inode->i_private);
}
static const struct file_operations rcubarrier_fops = {
.owner = THIS_MODULE,
.open = rcubarrier_open,
.read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
+ .llseek = no_llseek,
+ .release = seq_release,
};
#ifdef CONFIG_RCU_BOOST
@@ -84,12 +113,14 @@ static char convert_kthread_status(unsigned int kthread_status)
static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
{
+ long ql, qll;
+
if (!rdp->beenonline)
return;
- seq_printf(m, "%3d%cc=%lu g=%lu pq=%d qp=%d",
+ seq_printf(m, "%3d%cc=%ld g=%ld pq=%d qp=%d",
rdp->cpu,
cpu_is_offline(rdp->cpu) ? '!' : ' ',
- rdp->completed, rdp->gpnum,
+ ulong2long(rdp->completed), ulong2long(rdp->gpnum),
rdp->passed_quiesce, rdp->qs_pending);
seq_printf(m, " dt=%d/%llx/%d df=%lu",
atomic_read(&rdp->dynticks->dynticks),
@@ -97,8 +128,11 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
rdp->dynticks->dynticks_nmi_nesting,
rdp->dynticks_fqs);
seq_printf(m, " of=%lu", rdp->offline_fqs);
+ rcu_nocb_q_lengths(rdp, &ql, &qll);
+ qll += rdp->qlen_lazy;
+ ql += rdp->qlen;
seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
- rdp->qlen_lazy, rdp->qlen,
+ qll, ql,
".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
rdp->nxttail[RCU_NEXT_TAIL]],
".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
@@ -114,101 +148,67 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
#endif /* #ifdef CONFIG_RCU_BOOST */
seq_printf(m, " b=%ld", rdp->blimit);
- seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
- rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
+ seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
+ rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
+ rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
}
-static int show_rcudata(struct seq_file *m, void *unused)
+static int show_rcudata(struct seq_file *m, void *v)
{
- int cpu;
- struct rcu_state *rsp;
-
- for_each_rcu_flavor(rsp) {
- seq_printf(m, "%s:\n", rsp->name);
- for_each_possible_cpu(cpu)
- print_one_rcu_data(m, per_cpu_ptr(rsp->rda, cpu));
- }
+ print_one_rcu_data(m, (struct rcu_data *)v);
return 0;
}
+static const struct seq_operations rcudate_op = {
+ .start = r_start,
+ .next = r_next,
+ .stop = r_stop,
+ .show = show_rcudata,
+};
+
static int rcudata_open(struct inode *inode, struct file *file)
{
- return single_open(file, show_rcudata, NULL);
+ return r_open(inode, file, &rcudate_op);
}
static const struct file_operations rcudata_fops = {
.owner = THIS_MODULE,
.open = rcudata_open,
.read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
+ .llseek = no_llseek,
+ .release = seq_release,
};
-static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
-{
- if (!rdp->beenonline)
- return;
- seq_printf(m, "%d,%s,%lu,%lu,%d,%d",
- rdp->cpu,
- cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
- rdp->completed, rdp->gpnum,
- rdp->passed_quiesce, rdp->qs_pending);
- seq_printf(m, ",%d,%llx,%d,%lu",
- atomic_read(&rdp->dynticks->dynticks),
- rdp->dynticks->dynticks_nesting,
- rdp->dynticks->dynticks_nmi_nesting,
- rdp->dynticks_fqs);
- seq_printf(m, ",%lu", rdp->offline_fqs);
- seq_printf(m, ",%ld,%ld,\"%c%c%c%c\"", rdp->qlen_lazy, rdp->qlen,
- ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
- rdp->nxttail[RCU_NEXT_TAIL]],
- ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
- rdp->nxttail[RCU_NEXT_READY_TAIL]],
- ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
- rdp->nxttail[RCU_WAIT_TAIL]],
- ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
-#ifdef CONFIG_RCU_BOOST
- seq_printf(m, ",%d,\"%c\"",
- per_cpu(rcu_cpu_has_work, rdp->cpu),
- convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
- rdp->cpu)));
-#endif /* #ifdef CONFIG_RCU_BOOST */
- seq_printf(m, ",%ld", rdp->blimit);
- seq_printf(m, ",%lu,%lu,%lu\n",
- rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
-}
-
-static int show_rcudata_csv(struct seq_file *m, void *unused)
+static int show_rcuexp(struct seq_file *m, void *v)
{
- int cpu;
- struct rcu_state *rsp;
-
- seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pq\",");
- seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
- seq_puts(m, "\"of\",\"qll\",\"ql\",\"qs\"");
-#ifdef CONFIG_RCU_BOOST
- seq_puts(m, "\"kt\",\"ktl\"");
-#endif /* #ifdef CONFIG_RCU_BOOST */
- seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
- for_each_rcu_flavor(rsp) {
- seq_printf(m, "\"%s:\"\n", rsp->name);
- for_each_possible_cpu(cpu)
- print_one_rcu_data_csv(m, per_cpu_ptr(rsp->rda, cpu));
- }
+ struct rcu_state *rsp = (struct rcu_state *)m->private;
+
+ seq_printf(m, "s=%lu d=%lu w=%lu tf=%lu wd1=%lu wd2=%lu n=%lu sc=%lu dt=%lu dl=%lu dx=%lu\n",
+ atomic_long_read(&rsp->expedited_start),
+ atomic_long_read(&rsp->expedited_done),
+ atomic_long_read(&rsp->expedited_wrap),
+ atomic_long_read(&rsp->expedited_tryfail),
+ atomic_long_read(&rsp->expedited_workdone1),
+ atomic_long_read(&rsp->expedited_workdone2),
+ atomic_long_read(&rsp->expedited_normal),
+ atomic_long_read(&rsp->expedited_stoppedcpus),
+ atomic_long_read(&rsp->expedited_done_tries),
+ atomic_long_read(&rsp->expedited_done_lost),
+ atomic_long_read(&rsp->expedited_done_exit));
return 0;
}
-static int rcudata_csv_open(struct inode *inode, struct file *file)
+static int rcuexp_open(struct inode *inode, struct file *file)
{
- return single_open(file, show_rcudata_csv, NULL);
+ return single_open(file, show_rcuexp, inode->i_private);
}
-static const struct file_operations rcudata_csv_fops = {
+static const struct file_operations rcuexp_fops = {
.owner = THIS_MODULE,
- .open = rcudata_csv_open,
+ .open = rcuexp_open,
.read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
+ .llseek = no_llseek,
+ .release = seq_release,
};
#ifdef CONFIG_RCU_BOOST
@@ -254,27 +254,11 @@ static const struct file_operations rcu_node_boost_fops = {
.owner = THIS_MODULE,
.open = rcu_node_boost_open,
.read = seq_read,
- .llseek = seq_lseek,
+ .llseek = no_llseek,
.release = single_release,
};
-/*
- * Create the rcuboost debugfs entry. Standard error return.
- */
-static int rcu_boost_trace_create_file(struct dentry *rcudir)
-{
- return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
- &rcu_node_boost_fops);
-}
-
-#else /* #ifdef CONFIG_RCU_BOOST */
-
-static int rcu_boost_trace_create_file(struct dentry *rcudir)
-{
- return 0; /* There cannot be an error if we didn't create it! */
-}
-
-#endif /* #else #ifdef CONFIG_RCU_BOOST */
+#endif /* #ifdef CONFIG_RCU_BOOST */
static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
{
@@ -283,8 +267,9 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
struct rcu_node *rnp;
gpnum = rsp->gpnum;
- seq_printf(m, "%s: c=%lu g=%lu s=%d jfq=%ld j=%x ",
- rsp->name, rsp->completed, gpnum, rsp->fqs_state,
+ seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ",
+ ulong2long(rsp->completed), ulong2long(gpnum),
+ rsp->fqs_state,
(long)(rsp->jiffies_force_qs - jiffies),
(int)(jiffies & 0xffff));
seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
@@ -306,26 +291,24 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
seq_puts(m, "\n");
}
-static int show_rcuhier(struct seq_file *m, void *unused)
+static int show_rcuhier(struct seq_file *m, void *v)
{
- struct rcu_state *rsp;
-
- for_each_rcu_flavor(rsp)
- print_one_rcu_state(m, rsp);
+ struct rcu_state *rsp = (struct rcu_state *)m->private;
+ print_one_rcu_state(m, rsp);
return 0;
}
static int rcuhier_open(struct inode *inode, struct file *file)
{
- return single_open(file, show_rcuhier, NULL);
+ return single_open(file, show_rcuhier, inode->i_private);
}
static const struct file_operations rcuhier_fops = {
.owner = THIS_MODULE,
.open = rcuhier_open,
.read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
+ .llseek = no_llseek,
+ .release = seq_release,
};
static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
@@ -338,42 +321,42 @@ static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
struct rcu_node *rnp = &rsp->node[0];
raw_spin_lock_irqsave(&rnp->lock, flags);
- completed = rsp->completed;
- gpnum = rsp->gpnum;
- if (rsp->completed == rsp->gpnum)
+ completed = ACCESS_ONCE(rsp->completed);
+ gpnum = ACCESS_ONCE(rsp->gpnum);
+ if (completed == gpnum)
gpage = 0;
else
gpage = jiffies - rsp->gp_start;
gpmax = rsp->gp_max;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
- seq_printf(m, "%s: completed=%ld gpnum=%lu age=%ld max=%ld\n",
- rsp->name, completed, gpnum, gpage, gpmax);
+ seq_printf(m, "completed=%ld gpnum=%ld age=%ld max=%ld\n",
+ ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
}
-static int show_rcugp(struct seq_file *m, void *unused)
+static int show_rcugp(struct seq_file *m, void *v)
{
- struct rcu_state *rsp;
-
- for_each_rcu_flavor(rsp)
- show_one_rcugp(m, rsp);
+ struct rcu_state *rsp = (struct rcu_state *)m->private;
+ show_one_rcugp(m, rsp);
return 0;
}
static int rcugp_open(struct inode *inode, struct file *file)
{
- return single_open(file, show_rcugp, NULL);
+ return single_open(file, show_rcugp, inode->i_private);
}
static const struct file_operations rcugp_fops = {
.owner = THIS_MODULE,
.open = rcugp_open,
.read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
+ .llseek = no_llseek,
+ .release = seq_release,
};
static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
{
+ if (!rdp->beenonline)
+ return;
seq_printf(m, "%3d%cnp=%ld ",
rdp->cpu,
cpu_is_offline(rdp->cpu) ? '!' : ' ',
@@ -389,34 +372,30 @@ static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
rdp->n_rp_need_nothing);
}
-static int show_rcu_pending(struct seq_file *m, void *unused)
+static int show_rcu_pending(struct seq_file *m, void *v)
{
- int cpu;
- struct rcu_data *rdp;
- struct rcu_state *rsp;
-
- for_each_rcu_flavor(rsp) {
- seq_printf(m, "%s:\n", rsp->name);
- for_each_possible_cpu(cpu) {
- rdp = per_cpu_ptr(rsp->rda, cpu);
- if (rdp->beenonline)
- print_one_rcu_pending(m, rdp);
- }
- }
+ print_one_rcu_pending(m, (struct rcu_data *)v);
return 0;
}
+static const struct seq_operations rcu_pending_op = {
+ .start = r_start,
+ .next = r_next,
+ .stop = r_stop,
+ .show = show_rcu_pending,
+};
+
static int rcu_pending_open(struct inode *inode, struct file *file)
{
- return single_open(file, show_rcu_pending, NULL);
+ return r_open(inode, file, &rcu_pending_op);
}
static const struct file_operations rcu_pending_fops = {
.owner = THIS_MODULE,
.open = rcu_pending_open,
.read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
+ .llseek = no_llseek,
+ .release = seq_release,
};
static int show_rcutorture(struct seq_file *m, void *unused)
@@ -446,43 +425,58 @@ static struct dentry *rcudir;
static int __init rcutree_trace_init(void)
{
+ struct rcu_state *rsp;
struct dentry *retval;
+ struct dentry *rspdir;
rcudir = debugfs_create_dir("rcu", NULL);
if (!rcudir)
goto free_out;
- retval = debugfs_create_file("rcubarrier", 0444, rcudir,
- NULL, &rcubarrier_fops);
- if (!retval)
- goto free_out;
-
- retval = debugfs_create_file("rcudata", 0444, rcudir,
- NULL, &rcudata_fops);
- if (!retval)
- goto free_out;
-
- retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
- NULL, &rcudata_csv_fops);
- if (!retval)
- goto free_out;
-
- if (rcu_boost_trace_create_file(rcudir))
- goto free_out;
+ for_each_rcu_flavor(rsp) {
+ rspdir = debugfs_create_dir(rsp->name, rcudir);
+ if (!rspdir)
+ goto free_out;
+
+ retval = debugfs_create_file("rcudata", 0444,
+ rspdir, rsp, &rcudata_fops);
+ if (!retval)
+ goto free_out;
+
+ retval = debugfs_create_file("rcuexp", 0444,
+ rspdir, rsp, &rcuexp_fops);
+ if (!retval)
+ goto free_out;
+
+ retval = debugfs_create_file("rcu_pending", 0444,
+ rspdir, rsp, &rcu_pending_fops);
+ if (!retval)
+ goto free_out;
+
+ retval = debugfs_create_file("rcubarrier", 0444,
+ rspdir, rsp, &rcubarrier_fops);
+ if (!retval)
+ goto free_out;
- retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
- if (!retval)
- goto free_out;
+#ifdef CONFIG_RCU_BOOST
+ if (rsp == &rcu_preempt_state) {
+ retval = debugfs_create_file("rcuboost", 0444,
+ rspdir, NULL, &rcu_node_boost_fops);
+ if (!retval)
+ goto free_out;
+ }
+#endif
- retval = debugfs_create_file("rcuhier", 0444, rcudir,
- NULL, &rcuhier_fops);
- if (!retval)
- goto free_out;
+ retval = debugfs_create_file("rcugp", 0444,
+ rspdir, rsp, &rcugp_fops);
+ if (!retval)
+ goto free_out;
- retval = debugfs_create_file("rcu_pending", 0444, rcudir,
- NULL, &rcu_pending_fops);
- if (!retval)
- goto free_out;
+ retval = debugfs_create_file("rcuhier", 0444,
+ rspdir, rsp, &rcuhier_fops);
+ if (!retval)
+ goto free_out;
+ }
retval = debugfs_create_file("rcutorture", 0444, rcudir,
NULL, &rcutorture_fops);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2d8927fda71..80f80dfca70 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -72,6 +72,7 @@
#include <linux/slab.h>
#include <linux/init_task.h>
#include <linux/binfmts.h>
+#include <linux/context_tracking.h>
#include <asm/switch_to.h>
#include <asm/tlb.h>
@@ -1886,8 +1887,8 @@ context_switch(struct rq *rq, struct task_struct *prev,
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
#endif
+ context_tracking_task_switch(prev, next);
/* Here we just switch the register state and the stack. */
- rcu_switch(prev, next);
switch_to(prev, next, prev);
barrier();
@@ -2911,7 +2912,7 @@ asmlinkage void __sched schedule(void)
}
EXPORT_SYMBOL(schedule);
-#ifdef CONFIG_RCU_USER_QS
+#ifdef CONFIG_CONTEXT_TRACKING
asmlinkage void __sched schedule_user(void)
{
/*
@@ -2920,9 +2921,9 @@ asmlinkage void __sched schedule_user(void)
* we haven't yet exited the RCU idle mode. Do it here manually until
* we find a better solution.
*/
- rcu_user_exit();
+ user_exit();
schedule();
- rcu_user_enter();
+ user_enter();
}
#endif
@@ -3027,7 +3028,7 @@ asmlinkage void __sched preempt_schedule_irq(void)
/* Catch callers which need to be fixed */
BUG_ON(ti->preempt_count || !irqs_disabled());
- rcu_user_exit();
+ user_exit();
do {
add_preempt_count(PREEMPT_ACTIVE);
local_irq_enable();
@@ -4474,6 +4475,7 @@ static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
void sched_show_task(struct task_struct *p)
{
unsigned long free = 0;
+ int ppid;
unsigned state;
state = p->state ? __ffs(p->state) + 1 : 0;
@@ -4493,8 +4495,11 @@ void sched_show_task(struct task_struct *p)
#ifdef CONFIG_DEBUG_STACK_USAGE
free = stack_not_used(p);
#endif
+ rcu_read_lock();
+ ppid = task_pid_nr(rcu_dereference(p->real_parent));
+ rcu_read_unlock();
printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
- task_pid_nr(p), task_pid_nr(rcu_dereference(p->real_parent)),
+ task_pid_nr(p), ppid,
(unsigned long)task_thread_info(p)->flags);
show_stack(p, NULL);
@@ -8076,3 +8081,9 @@ struct cgroup_subsys cpuacct_subsys = {
.base_cftypes = files,
};
#endif /* CONFIG_CGROUP_CPUACCT */
+
+void dump_cpu_task(int cpu)
+{
+ pr_info("Task dump for CPU %d:\n", cpu);
+ sched_show_task(cpu_curr(cpu));
+}
diff --git a/kernel/srcu.c b/kernel/srcu.c
index 97c465ebd84..2b859828cdc 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -16,8 +16,10 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) IBM Corporation, 2006
+ * Copyright (C) Fujitsu, 2012
*
* Author: Paul McKenney <paulmck@us.ibm.com>
+ * Lai Jiangshan <laijs@cn.fujitsu.com>
*
* For detailed explanation of Read-Copy Update mechanism see -
* Documentation/RCU/ *.txt
@@ -34,6 +36,10 @@
#include <linux/delay.h>
#include <linux/srcu.h>
+#include <trace/events/rcu.h>
+
+#include "rcu.h"
+
/*
* Initialize an rcu_batch structure to empty.
*/
@@ -92,9 +98,6 @@ static inline void rcu_batch_move(struct rcu_batch *to, struct rcu_batch *from)
}
}
-/* single-thread state-machine */
-static void process_srcu(struct work_struct *work);
-
static int init_srcu_struct_fields(struct srcu_struct *sp)
{
sp->completed = 0;
@@ -464,7 +467,9 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount)
*/
void synchronize_srcu(struct srcu_struct *sp)
{
- __synchronize_srcu(sp, SYNCHRONIZE_SRCU_TRYCOUNT);
+ __synchronize_srcu(sp, rcu_expedited
+ ? SYNCHRONIZE_SRCU_EXP_TRYCOUNT
+ : SYNCHRONIZE_SRCU_TRYCOUNT);
}
EXPORT_SYMBOL_GPL(synchronize_srcu);
@@ -637,7 +642,7 @@ static void srcu_reschedule(struct srcu_struct *sp)
/*
* This is the work-queue function that handles SRCU grace periods.
*/
-static void process_srcu(struct work_struct *work)
+void process_srcu(struct work_struct *work)
{
struct srcu_struct *sp;
@@ -648,3 +653,4 @@ static void process_srcu(struct work_struct *work)
srcu_invoke_callbacks(sp);
srcu_reschedule(sp);
}
+EXPORT_SYMBOL_GPL(process_srcu);
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-28 15:36:40 +0000