Merge branches 'doctorture.2013.01.29a', 'fixes.2013.01.26a', 'tagcb.2013.01.24a' and 'tiny.2013.01.29b' into HEAD
doctorture.2013.01.11a: Changes to rcutorture and to RCU documentation.
fixes.2013.01.26a: Miscellaneous fixes.
tagcb.2013.01.24a: Tag RCU callbacks with grace-period number to
simplify callback advancement.
tiny.2013.01.29b: Enhancements to uniprocessor handling in tiny RCU.
diff --git a/Documentation/atomic_ops.txt b/Documentation/atomic_ops.txt
index 27f2b21..d9ca5be 100644
--- a/Documentation/atomic_ops.txt
+++ b/Documentation/atomic_ops.txt
@@ -253,6 +253,8 @@
the given new value. It returns the old value that the atomic variable v had
just before the operation.
+atomic_xchg requires explicit memory barriers around the operation.
+
int atomic_cmpxchg(atomic_t *v, int old, int new);
This performs an atomic compare exchange operation on the atomic value v,
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 3c4e1b3..fa5d8a9 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -1685,6 +1685,7 @@
xchg();
cmpxchg();
+ atomic_xchg();
atomic_cmpxchg();
atomic_inc_return();
atomic_dec_return();
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 275aa3f..b758ce1 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -53,7 +53,10 @@
extern void rcutorture_record_test_transition(void);
extern void rcutorture_record_progress(unsigned long vernum);
extern void do_trace_rcu_torture_read(char *rcutorturename,
- struct rcu_head *rhp);
+ struct rcu_head *rhp,
+ unsigned long secs,
+ unsigned long c_old,
+ unsigned long c);
#else
static inline void rcutorture_record_test_transition(void)
{
@@ -63,9 +66,13 @@
}
#ifdef CONFIG_RCU_TRACE
extern void do_trace_rcu_torture_read(char *rcutorturename,
- struct rcu_head *rhp);
+ struct rcu_head *rhp,
+ unsigned long secs,
+ unsigned long c_old,
+ unsigned long c);
#else
-#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
+ do { } while (0)
#endif
#endif
@@ -749,7 +756,7 @@
* preemptible RCU implementations (TREE_PREEMPT_RCU and TINY_PREEMPT_RCU)
* in CONFIG_PREEMPT kernel builds, RCU read-side critical sections may
* be preempted, but explicit blocking is illegal. Finally, in preemptible
- * RCU implementations in real-time (CONFIG_PREEMPT_RT) kernel builds,
+ * RCU implementations in real-time (with -rt patchset) kernel builds,
* RCU read-side critical sections may be preempted and they may also
* block, but only when acquiring spinlocks that are subject to priority
* inheritance.
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 5678114..1918e83 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -395,7 +395,7 @@
*/
TRACE_EVENT(rcu_batch_start,
- TP_PROTO(char *rcuname, long qlen_lazy, long qlen, int blimit),
+ TP_PROTO(char *rcuname, long qlen_lazy, long qlen, long blimit),
TP_ARGS(rcuname, qlen_lazy, qlen, blimit),
@@ -403,7 +403,7 @@
__field(char *, rcuname)
__field(long, qlen_lazy)
__field(long, qlen)
- __field(int, blimit)
+ __field(long, blimit)
),
TP_fast_assign(
@@ -413,7 +413,7 @@
__entry->blimit = blimit;
),
- TP_printk("%s CBs=%ld/%ld bl=%d",
+ TP_printk("%s CBs=%ld/%ld bl=%ld",
__entry->rcuname, __entry->qlen_lazy, __entry->qlen,
__entry->blimit)
);
@@ -525,22 +525,30 @@
*/
TRACE_EVENT(rcu_torture_read,
- TP_PROTO(char *rcutorturename, struct rcu_head *rhp),
+ TP_PROTO(char *rcutorturename, struct rcu_head *rhp,
+ unsigned long secs, unsigned long c_old, unsigned long c),
- TP_ARGS(rcutorturename, rhp),
+ TP_ARGS(rcutorturename, rhp, secs, c_old, c),
TP_STRUCT__entry(
__field(char *, rcutorturename)
__field(struct rcu_head *, rhp)
+ __field(unsigned long, secs)
+ __field(unsigned long, c_old)
+ __field(unsigned long, c)
),
TP_fast_assign(
__entry->rcutorturename = rcutorturename;
__entry->rhp = rhp;
+ __entry->secs = secs;
+ __entry->c_old = c_old;
+ __entry->c = c;
),
- TP_printk("%s torture read %p",
- __entry->rcutorturename, __entry->rhp)
+ TP_printk("%s torture read %p %luus c: %lu %lu",
+ __entry->rcutorturename, __entry->rhp,
+ __entry->secs, __entry->c_old, __entry->c)
);
/*
@@ -610,7 +618,8 @@
#define trace_rcu_invoke_kfree_callback(rcuname, rhp, offset) do { } while (0)
#define trace_rcu_batch_end(rcuname, callbacks_invoked, cb, nr, iit, risk) \
do { } while (0)
-#define trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#define trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
+ do { } while (0)
#define trace_rcu_barrier(name, s, cpu, cnt, done) do { } while (0)
#endif /* #else #ifdef CONFIG_RCU_TRACE */
diff --git a/init/Kconfig b/init/Kconfig
index 7d30240..fb19b46 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -453,7 +453,7 @@
config TREE_PREEMPT_RCU
bool "Preemptible tree-based hierarchical RCU"
- depends on PREEMPT && SMP
+ depends on PREEMPT
help
This option selects the RCU implementation that is
designed for very large SMP systems with hundreds or
@@ -461,6 +461,8 @@
is also required. It also scales down nicely to
smaller systems.
+ Select this option if you are unsure.
+
config TINY_RCU
bool "UP-only small-memory-footprint RCU"
depends on !PREEMPT && !SMP
@@ -486,6 +488,14 @@
This option enables preemptible-RCU code that is common between
the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
+config RCU_STALL_COMMON
+ def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
+ help
+ This option enables RCU CPU stall code that is common between
+ the TINY and TREE variants of RCU. The purpose is to allow
+ the tiny variants to disable RCU CPU stall warnings, while
+ making these warnings mandatory for the tree variants.
+
config CONTEXT_TRACKING
bool
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index e0e07fd..d566aba 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -1,3 +1,19 @@
+/*
+ * Context tracking: Probe on high level context boundaries such as kernel
+ * and userspace. This includes syscalls and exceptions entry/exit.
+ *
+ * This is used by RCU to remove its dependency on the timer tick while a CPU
+ * runs in userspace.
+ *
+ * Started by Frederic Weisbecker:
+ *
+ * Copyright (C) 2012 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
+ *
+ * Many thanks to Gilad Ben-Yossef, Paul McKenney, Ingo Molnar, Andrew Morton,
+ * Steven Rostedt, Peter Zijlstra for suggestions and improvements.
+ *
+ */
+
#include <linux/context_tracking.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
@@ -6,8 +22,8 @@
struct context_tracking {
/*
- * When active is false, hooks are not set to
- * minimize overhead: TIF flags are cleared
+ * When active is false, probes are unset in order
+ * to minimize overhead: TIF flags are cleared
* and calls to user_enter/exit are ignored. This
* may be further optimized using static keys.
*/
@@ -24,6 +40,15 @@
#endif
};
+/**
+ * user_enter - Inform the context tracking that the CPU is going to
+ * enter userspace mode.
+ *
+ * This function must be called right before we switch from the kernel
+ * to userspace, when it's guaranteed the remaining kernel instructions
+ * to execute won't use any RCU read side critical section because this
+ * function sets RCU in extended quiescent state.
+ */
void user_enter(void)
{
unsigned long flags;
@@ -39,40 +64,70 @@
if (in_interrupt())
return;
+ /* Kernel threads aren't supposed to go to userspace */
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);
+ /*
+ * At this stage, only low level arch entry code remains and
+ * then we'll run in userspace. We can assume there won't be
+ * any RCU read-side critical section until the next call to
+ * user_exit() or rcu_irq_enter(). Let's remove RCU's dependency
+ * on the tick.
+ */
rcu_user_enter();
}
local_irq_restore(flags);
}
+
+/**
+ * user_exit - Inform the context tracking that the CPU is
+ * exiting userspace mode and entering the kernel.
+ *
+ * This function must be called after we entered the kernel from userspace
+ * before any use of RCU read side critical section. This potentially include
+ * any high level kernel code like syscalls, exceptions, signal handling, etc...
+ *
+ * This call supports re-entrancy. This way it can be called from any exception
+ * handler without needing to know if we came from userspace or not.
+ */
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);
+ /*
+ * We are going to run code that may use RCU. Inform
+ * RCU core about that (ie: we may need the tick again).
+ */
rcu_user_exit();
}
local_irq_restore(flags);
}
+
+/**
+ * context_tracking_task_switch - context switch the syscall callbacks
+ * @prev: the task that is being switched out
+ * @next: the task that is being switched in
+ *
+ * The context tracking uses the syscall slow path to implement its user-kernel
+ * boundaries probes on syscalls. This way it doesn't impact the syscall fast
+ * path on CPUs that don't do context tracking.
+ *
+ * But we need to clear the flag on the previous task because it may later
+ * migrate to some CPU that doesn't do the context tracking. As such the TIF
+ * flag may not be desired there.
+ */
void context_tracking_task_switch(struct task_struct *prev,
struct task_struct *next)
{
diff --git a/kernel/rcu.h b/kernel/rcu.h
index 20dfba5..7f8e759 100644
--- a/kernel/rcu.h
+++ b/kernel/rcu.h
@@ -111,4 +111,11 @@
extern int rcu_expedited;
+#ifdef CONFIG_RCU_STALL_COMMON
+
+extern int rcu_cpu_stall_suppress;
+int rcu_jiffies_till_stall_check(void);
+
+#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
+
#endif /* __LINUX_RCU_H */
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index a2cf761..48ab703 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -404,11 +404,65 @@
#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE)
-void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp)
+void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp,
+ unsigned long secs,
+ unsigned long c_old, unsigned long c)
{
- trace_rcu_torture_read(rcutorturename, rhp);
+ trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c);
}
EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
#else
-#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
+ do { } while (0)
#endif
+
+#ifdef CONFIG_RCU_STALL_COMMON
+
+#ifdef CONFIG_PROVE_RCU
+#define RCU_STALL_DELAY_DELTA (5 * HZ)
+#else
+#define RCU_STALL_DELAY_DELTA 0
+#endif
+
+int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
+int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
+
+module_param(rcu_cpu_stall_suppress, int, 0644);
+module_param(rcu_cpu_stall_timeout, int, 0644);
+
+int rcu_jiffies_till_stall_check(void)
+{
+ int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout);
+
+ /*
+ * Limit check must be consistent with the Kconfig limits
+ * for CONFIG_RCU_CPU_STALL_TIMEOUT.
+ */
+ if (till_stall_check < 3) {
+ ACCESS_ONCE(rcu_cpu_stall_timeout) = 3;
+ till_stall_check = 3;
+ } else if (till_stall_check > 300) {
+ ACCESS_ONCE(rcu_cpu_stall_timeout) = 300;
+ till_stall_check = 300;
+ }
+ return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
+}
+
+static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
+{
+ rcu_cpu_stall_suppress = 1;
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block rcu_panic_block = {
+ .notifier_call = rcu_panic,
+};
+
+static int __init check_cpu_stall_init(void)
+{
+ atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
+ return 0;
+}
+early_initcall(check_cpu_stall_init);
+
+#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index e7dce58..a0714a5 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -51,10 +51,10 @@
void (*func)(struct rcu_head *rcu),
struct rcu_ctrlblk *rcp);
-#include "rcutiny_plugin.h"
-
static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
+#include "rcutiny_plugin.h"
+
/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */
static void rcu_idle_enter_common(long long newval)
{
@@ -193,7 +193,7 @@
* interrupts don't count, we must be running at the first interrupt
* level.
*/
-int rcu_is_cpu_rrupt_from_idle(void)
+static int rcu_is_cpu_rrupt_from_idle(void)
{
return rcu_dynticks_nesting <= 1;
}
@@ -205,6 +205,7 @@
*/
static int rcu_qsctr_help(struct rcu_ctrlblk *rcp)
{
+ reset_cpu_stall_ticks(rcp);
if (rcp->rcucblist != NULL &&
rcp->donetail != rcp->curtail) {
rcp->donetail = rcp->curtail;
@@ -251,6 +252,7 @@
*/
void rcu_check_callbacks(int cpu, int user)
{
+ check_cpu_stalls();
if (user || rcu_is_cpu_rrupt_from_idle())
rcu_sched_qs(cpu);
else if (!in_softirq())
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index f85016a..8a23300 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -33,6 +33,9 @@
struct rcu_head **donetail; /* ->next pointer of last "done" CB. */
struct rcu_head **curtail; /* ->next pointer of last CB. */
RCU_TRACE(long qlen); /* Number of pending CBs. */
+ RCU_TRACE(unsigned long gp_start); /* Start time for stalls. */
+ RCU_TRACE(unsigned long ticks_this_gp); /* Statistic for stalls. */
+ RCU_TRACE(unsigned long jiffies_stall); /* Jiffies at next stall. */
RCU_TRACE(char *name); /* Name of RCU type. */
};
@@ -54,6 +57,51 @@
EXPORT_SYMBOL_GPL(rcu_scheduler_active);
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+#ifdef CONFIG_RCU_TRACE
+
+static void check_cpu_stall(struct rcu_ctrlblk *rcp)
+{
+ unsigned long j;
+ unsigned long js;
+
+ if (rcu_cpu_stall_suppress)
+ return;
+ rcp->ticks_this_gp++;
+ j = jiffies;
+ js = rcp->jiffies_stall;
+ if (*rcp->curtail && ULONG_CMP_GE(j, js)) {
+ pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
+ rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting,
+ jiffies - rcp->gp_start, rcp->qlen);
+ dump_stack();
+ }
+ if (*rcp->curtail && ULONG_CMP_GE(j, js))
+ rcp->jiffies_stall = jiffies +
+ 3 * rcu_jiffies_till_stall_check() + 3;
+ else if (ULONG_CMP_GE(j, js))
+ rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
+}
+
+static void check_cpu_stall_preempt(void);
+
+#endif /* #ifdef CONFIG_RCU_TRACE */
+
+static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
+{
+#ifdef CONFIG_RCU_TRACE
+ rcp->ticks_this_gp = 0;
+ rcp->gp_start = jiffies;
+ rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
+#endif /* #ifdef CONFIG_RCU_TRACE */
+}
+
+static void check_cpu_stalls(void)
+{
+ RCU_TRACE(check_cpu_stall(&rcu_bh_ctrlblk));
+ RCU_TRACE(check_cpu_stall(&rcu_sched_ctrlblk));
+ RCU_TRACE(check_cpu_stall_preempt());
+}
+
#ifdef CONFIG_TINY_PREEMPT_RCU
#include <linux/delay.h>
@@ -448,6 +496,7 @@
/* Official start of GP. */
rcu_preempt_ctrlblk.gpnum++;
RCU_TRACE(rcu_preempt_ctrlblk.n_grace_periods++);
+ reset_cpu_stall_ticks(&rcu_preempt_ctrlblk.rcb);
/* Any blocked RCU readers block new GP. */
if (rcu_preempt_blocked_readers_any())
@@ -1054,4 +1103,11 @@
MODULE_DESCRIPTION("Read-Copy Update tracing for tiny implementation");
MODULE_LICENSE("GPL");
+static void check_cpu_stall_preempt(void)
+{
+#ifdef CONFIG_TINY_PREEMPT_RCU
+ check_cpu_stall(&rcu_preempt_ctrlblk.rcb);
+#endif /* #ifdef CONFIG_TINY_PREEMPT_RCU */
+}
+
#endif /* #ifdef CONFIG_RCU_TRACE */
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 31dea01..cd4c35d 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -46,6 +46,7 @@
#include <linux/stat.h>
#include <linux/srcu.h>
#include <linux/slab.h>
+#include <linux/trace_clock.h>
#include <asm/byteorder.h>
MODULE_LICENSE("GPL");
@@ -845,7 +846,7 @@
/* Wait for the next test interval. */
oldstarttime = boost_starttime;
while (ULONG_CMP_LT(jiffies, oldstarttime)) {
- schedule_timeout_uninterruptible(1);
+ schedule_timeout_interruptible(oldstarttime - jiffies);
rcu_stutter_wait("rcu_torture_boost");
if (kthread_should_stop() ||
fullstop != FULLSTOP_DONTSTOP)
@@ -1028,7 +1029,6 @@
return;
if (atomic_xchg(&beenhere, 1) != 0)
return;
- do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
ftrace_dump(DUMP_ALL);
}
@@ -1042,13 +1042,16 @@
{
int idx;
int completed;
+ int completed_end;
static DEFINE_RCU_RANDOM(rand);
static DEFINE_SPINLOCK(rand_lock);
struct rcu_torture *p;
int pipe_count;
+ unsigned long long ts;
idx = cur_ops->readlock();
completed = cur_ops->completed();
+ ts = trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
@@ -1058,7 +1061,6 @@
cur_ops->readunlock(idx);
return;
}
- do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
spin_lock(&rand_lock);
@@ -1071,10 +1073,16 @@
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
- if (pipe_count > 1)
+ completed_end = cur_ops->completed();
+ if (pipe_count > 1) {
+ unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
+
+ do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
+ completed, completed_end);
rcutorture_trace_dump();
+ }
__this_cpu_inc(rcu_torture_count[pipe_count]);
- completed = cur_ops->completed() - completed;
+ completed = completed_end - completed;
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
@@ -1094,11 +1102,13 @@
rcu_torture_reader(void *arg)
{
int completed;
+ int completed_end;
int idx;
DEFINE_RCU_RANDOM(rand);
struct rcu_torture *p;
int pipe_count;
struct timer_list t;
+ unsigned long long ts;
VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
set_user_nice(current, 19);
@@ -1112,6 +1122,7 @@
}
idx = cur_ops->readlock();
completed = cur_ops->completed();
+ ts = trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
@@ -1122,7 +1133,6 @@
schedule_timeout_interruptible(HZ);
continue;
}
- do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
cur_ops->read_delay(&rand);
@@ -1132,10 +1142,17 @@
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
- if (pipe_count > 1)
+ completed_end = cur_ops->completed();
+ if (pipe_count > 1) {
+ unsigned long __maybe_unused ts_rem =
+ do_div(ts, NSEC_PER_USEC);
+
+ do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
+ ts, completed, completed_end);
rcutorture_trace_dump();
+ }
__this_cpu_inc(rcu_torture_count[pipe_count]);
- completed = cur_ops->completed() - completed;
+ completed = completed_end - completed;
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
@@ -1301,19 +1318,35 @@
set_cpus_allowed_ptr(reader_tasks[i],
shuffle_tmp_mask);
}
-
if (fakewriter_tasks) {
for (i = 0; i < nfakewriters; i++)
if (fakewriter_tasks[i])
set_cpus_allowed_ptr(fakewriter_tasks[i],
shuffle_tmp_mask);
}
-
if (writer_task)
set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
-
if (stats_task)
set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
+ if (stutter_task)
+ set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
+ if (fqs_task)
+ set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
+ if (shutdown_task)
+ set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
+#ifdef CONFIG_HOTPLUG_CPU
+ if (onoff_task)
+ set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
+#endif /* #ifdef CONFIG_HOTPLUG_CPU */
+ if (stall_task)
+ set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
+ if (barrier_cbs_tasks)
+ for (i = 0; i < n_barrier_cbs; i++)
+ if (barrier_cbs_tasks[i])
+ set_cpus_allowed_ptr(barrier_cbs_tasks[i],
+ shuffle_tmp_mask);
+ if (barrier_task)
+ set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
if (rcu_idle_cpu == -1)
rcu_idle_cpu = num_online_cpus() - 1;
@@ -1749,7 +1782,7 @@
barrier_cbs_wq =
kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
GFP_KERNEL);
- if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0)
+ if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
return -ENOMEM;
for (i = 0; i < n_barrier_cbs; i++) {
init_waitqueue_head(&barrier_cbs_wq[i]);
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index e9dce4f..5b8ad82 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -105,7 +105,7 @@
* The rcu_scheduler_active variable transitions from zero to one just
* before the first task is spawned. So when this variable is zero, RCU
* can assume that there is but one task, allowing RCU to (for example)
- * optimized synchronize_sched() to a simple barrier(). When this variable
+ * optimize synchronize_sched() to a simple barrier(). When this variable
* is one, RCU must actually do all the hard work required to detect real
* grace periods. This variable is also used to suppress boot-time false
* positives from lockdep-RCU error checking.
@@ -217,12 +217,6 @@
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;
-
-module_param(rcu_cpu_stall_suppress, int, 0644);
-module_param(rcu_cpu_stall_timeout, int, 0644);
-
static ulong jiffies_till_first_fqs = RCU_JIFFIES_TILL_FORCE_QS;
static ulong jiffies_till_next_fqs = RCU_JIFFIES_TILL_FORCE_QS;
@@ -346,7 +340,7 @@
static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval,
bool user)
{
- trace_rcu_dyntick("Start", oldval, 0);
+ trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting);
if (!user && !is_idle_task(current)) {
struct task_struct *idle = idle_task(smp_processor_id());
@@ -737,7 +731,7 @@
* interrupt from idle, return true. The caller must have at least
* disabled preemption.
*/
-int rcu_is_cpu_rrupt_from_idle(void)
+static int rcu_is_cpu_rrupt_from_idle(void)
{
return __get_cpu_var(rcu_dynticks).dynticks_nesting <= 1;
}
@@ -803,28 +797,10 @@
return 0;
}
-static int jiffies_till_stall_check(void)
-{
- int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout);
-
- /*
- * Limit check must be consistent with the Kconfig limits
- * for CONFIG_RCU_CPU_STALL_TIMEOUT.
- */
- if (till_stall_check < 3) {
- ACCESS_ONCE(rcu_cpu_stall_timeout) = 3;
- till_stall_check = 3;
- } else if (till_stall_check > 300) {
- ACCESS_ONCE(rcu_cpu_stall_timeout) = 300;
- till_stall_check = 300;
- }
- return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
-}
-
static void record_gp_stall_check_time(struct rcu_state *rsp)
{
rsp->gp_start = jiffies;
- rsp->jiffies_stall = jiffies + jiffies_till_stall_check();
+ rsp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
}
/*
@@ -867,7 +843,7 @@
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
- rsp->jiffies_stall = jiffies + 3 * jiffies_till_stall_check() + 3;
+ rsp->jiffies_stall = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
/*
@@ -945,7 +921,7 @@
raw_spin_lock_irqsave(&rnp->lock, flags);
if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall))
rsp->jiffies_stall = jiffies +
- 3 * jiffies_till_stall_check() + 3;
+ 3 * rcu_jiffies_till_stall_check() + 3;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
set_need_resched(); /* kick ourselves to get things going. */
@@ -976,12 +952,6 @@
}
}
-static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
-{
- rcu_cpu_stall_suppress = 1;
- return NOTIFY_DONE;
-}
-
/**
* rcu_cpu_stall_reset - prevent further stall warnings in current grace period
*
@@ -999,15 +969,6 @@
rsp->jiffies_stall = jiffies + ULONG_MAX / 2;
}
-static struct notifier_block rcu_panic_block = {
- .notifier_call = rcu_panic,
-};
-
-static void __init check_cpu_stall_init(void)
-{
- atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
-}
-
/*
* Update CPU-local rcu_data state to record the newly noticed grace period.
* This is used both when we started the grace period and when we notice
@@ -2864,9 +2825,6 @@
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
-#ifdef CONFIG_RCU_USER_QS
- WARN_ON_ONCE(rdp->dynticks->in_user);
-#endif
rdp->cpu = cpu;
rdp->rsp = rsp;
rcu_boot_init_nocb_percpu_data(rdp);
@@ -3083,6 +3041,10 @@
BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */
+ /* Silence gcc 4.8 warning about array index out of range. */
+ if (rcu_num_lvls > RCU_NUM_LVLS)
+ panic("rcu_init_one: rcu_num_lvls overflow");
+
/* Initialize the level-tracking arrays. */
for (i = 0; i < rcu_num_lvls; i++)
@@ -3219,7 +3181,6 @@
cpu_notifier(rcu_cpu_notify, 0);
for_each_online_cpu(cpu)
rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
- check_cpu_stall_init();
}
#include "rcutree_plugin.h"
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index c9f362e..c896b50 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -102,10 +102,6 @@
/* idle-period nonlazy_posted snapshot. */
int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
-#ifdef CONFIG_RCU_USER_QS
- bool ignore_user_qs; /* Treat userspace as extended QS or not */
- bool in_user; /* Is the CPU in userland from RCU POV? */
-#endif
};
/* RCU's kthread states for tracing. */
@@ -345,11 +341,6 @@
#define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */
-#ifdef CONFIG_PROVE_RCU
-#define RCU_STALL_DELAY_DELTA (5 * HZ)
-#else
-#define RCU_STALL_DELAY_DELTA 0
-#endif
#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */
/* to take at least one */
/* scheduling clock irq */
diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c
index 3947835..1bbb1b2 100644
--- a/kernel/trace/trace_clock.c
+++ b/kernel/trace/trace_clock.c
@@ -44,6 +44,7 @@
return clock;
}
+EXPORT_SYMBOL_GPL(trace_clock_local);
/*
* trace_clock(): 'between' trace clock. Not completely serialized,
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 3a35309..92203e4 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -605,61 +605,6 @@
For more details, see Documentation/lockdep-design.txt.
-config PROVE_RCU
- bool "RCU debugging: prove RCU correctness"
- depends on PROVE_LOCKING
- default n
- help
- This feature enables lockdep extensions that check for correct
- use of RCU APIs. This is currently under development. Say Y
- if you want to debug RCU usage or help work on the PROVE_RCU
- feature.
-
- Say N if you are unsure.
-
-config PROVE_RCU_REPEATEDLY
- bool "RCU debugging: don't disable PROVE_RCU on first splat"
- depends on PROVE_RCU
- default n
- help
- By itself, PROVE_RCU will disable checking upon issuing the
- first warning (or "splat"). This feature prevents such
- disabling, allowing multiple RCU-lockdep warnings to be printed
- on a single reboot.
-
- Say Y to allow multiple RCU-lockdep warnings per boot.
-
- Say N if you are unsure.
-
-config PROVE_RCU_DELAY
- bool "RCU debugging: preemptible RCU race provocation"
- depends on DEBUG_KERNEL && PREEMPT_RCU
- default n
- help
- There is a class of races that involve an unlikely preemption
- of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
- been set to INT_MIN. This feature inserts a delay at that
- point to increase the probability of these races.
-
- Say Y to increase probability of preemption of __rcu_read_unlock().
-
- Say N if you are unsure.
-
-config SPARSE_RCU_POINTER
- bool "RCU debugging: sparse-based checks for pointer usage"
- default n
- help
- This feature enables the __rcu sparse annotation for
- RCU-protected pointers. This annotation will cause sparse
- to flag any non-RCU used of annotated pointers. This can be
- helpful when debugging RCU usage. Please note that this feature
- is not intended to enforce code cleanliness; it is instead merely
- a debugging aid.
-
- Say Y to make sparse flag questionable use of RCU-protected pointers
-
- Say N if you are unsure.
-
config LOCKDEP
bool
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
@@ -937,6 +882,63 @@
BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
what it believes to be lockup conditions.
+menu "RCU Debugging"
+
+config PROVE_RCU
+ bool "RCU debugging: prove RCU correctness"
+ depends on PROVE_LOCKING
+ default n
+ help
+ This feature enables lockdep extensions that check for correct
+ use of RCU APIs. This is currently under development. Say Y
+ if you want to debug RCU usage or help work on the PROVE_RCU
+ feature.
+
+ Say N if you are unsure.
+
+config PROVE_RCU_REPEATEDLY
+ bool "RCU debugging: don't disable PROVE_RCU on first splat"
+ depends on PROVE_RCU
+ default n
+ help
+ By itself, PROVE_RCU will disable checking upon issuing the
+ first warning (or "splat"). This feature prevents such
+ disabling, allowing multiple RCU-lockdep warnings to be printed
+ on a single reboot.
+
+ Say Y to allow multiple RCU-lockdep warnings per boot.
+
+ Say N if you are unsure.
+
+config PROVE_RCU_DELAY
+ bool "RCU debugging: preemptible RCU race provocation"
+ depends on DEBUG_KERNEL && PREEMPT_RCU
+ default n
+ help
+ There is a class of races that involve an unlikely preemption
+ of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
+ been set to INT_MIN. This feature inserts a delay at that
+ point to increase the probability of these races.
+
+ Say Y to increase probability of preemption of __rcu_read_unlock().
+
+ Say N if you are unsure.
+
+config SPARSE_RCU_POINTER
+ bool "RCU debugging: sparse-based checks for pointer usage"
+ default n
+ help
+ This feature enables the __rcu sparse annotation for
+ RCU-protected pointers. This annotation will cause sparse
+ to flag any non-RCU used of annotated pointers. This can be
+ helpful when debugging RCU usage. Please note that this feature
+ is not intended to enforce code cleanliness; it is instead merely
+ a debugging aid.
+
+ Say Y to make sparse flag questionable use of RCU-protected pointers
+
+ Say N if you are unsure.
+
config RCU_TORTURE_TEST
tristate "torture tests for RCU"
depends on DEBUG_KERNEL
@@ -970,7 +972,7 @@
config RCU_CPU_STALL_TIMEOUT
int "RCU CPU stall timeout in seconds"
- depends on TREE_RCU || TREE_PREEMPT_RCU
+ depends on RCU_STALL_COMMON
range 3 300
default 21
help
@@ -1008,6 +1010,7 @@
config RCU_TRACE
bool "Enable tracing for RCU"
depends on DEBUG_KERNEL
+ select TRACE_CLOCK
help
This option provides tracing in RCU which presents stats
in debugfs for debugging RCU implementation.
@@ -1015,6 +1018,8 @@
Say Y here if you want to enable RCU tracing
Say N if you are unsure.
+endmenu # "RCU Debugging"
+
config KPROBES_SANITY_TEST
bool "Kprobes sanity tests"
depends on DEBUG_KERNEL
