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Message-Id: <1320265849-5744-8-git-send-email-paulmck@linux.vnet.ibm.com>
Date: Wed, 2 Nov 2011 13:30:29 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
dhowells@...hat.com, eric.dumazet@...il.com, darren@...art.com,
patches@...aro.org, "Paul E. McKenney" <paul.mckenney@...aro.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH RFC tip/core/rcu 08/28] rcu: Add failure tracing to rcutorture
From: Paul E. McKenney <paul.mckenney@...aro.org>
Trace the rcutorture RCU accesses and dump the trace buffer when the
first failure is detected.
Signed-off-by: Paul E. McKenney <paul.mckenney@...aro.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
include/linux/rcupdate.h | 8 ++++++++
include/trace/events/rcu.h | 26 ++++++++++++++++++++++++++
kernel/rcupdate.c | 10 ++++++++++
kernel/rcutorture.c | 18 ++++++++++++++++++
4 files changed, 62 insertions(+), 0 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index cd1ad4b..8d315b0 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -51,6 +51,8 @@ extern int rcutorture_runnable; /* for sysctl */
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
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);
#else
static inline void rcutorture_record_test_transition(void)
{
@@ -58,6 +60,12 @@ static inline void rcutorture_record_test_transition(void)
static inline void rcutorture_record_progress(unsigned long vernum)
{
}
+#ifdef CONFIG_RCU_TRACE
+extern void do_trace_rcu_torture_read(char *rcutorturename,
+ struct rcu_head *rhp);
+#else
+#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#endif
#endif
#define UINT_CMP_GE(a, b) (UINT_MAX / 2 >= (a) - (b))
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index e577180..172620a 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -437,6 +437,31 @@ TRACE_EVENT(rcu_batch_end,
__entry->rcuname, __entry->callbacks_invoked)
);
+/*
+ * Tracepoint for rcutorture readers. The first argument is the name
+ * of the RCU flavor from rcutorture's viewpoint and the second argument
+ * is the callback address.
+ */
+TRACE_EVENT(rcu_torture_read,
+
+ TP_PROTO(char *rcutorturename, struct rcu_head *rhp),
+
+ TP_ARGS(rcutorturename, rhp),
+
+ TP_STRUCT__entry(
+ __field(char *, rcutorturename)
+ __field(struct rcu_head *, rhp)
+ ),
+
+ TP_fast_assign(
+ __entry->rcutorturename = rcutorturename;
+ __entry->rhp = rhp;
+ ),
+
+ TP_printk("%s torture read %p",
+ __entry->rcutorturename, __entry->rhp)
+);
+
#else /* #ifdef CONFIG_RCU_TRACE */
#define trace_rcu_grace_period(rcuname, gpnum, gpevent) do { } while (0)
@@ -452,6 +477,7 @@ TRACE_EVENT(rcu_batch_end,
#define trace_rcu_invoke_callback(rcuname, rhp) do { } while (0)
#define trace_rcu_invoke_kfree_callback(rcuname, rhp, offset) do { } while (0)
#define trace_rcu_batch_end(rcuname, callbacks_invoked) do { } while (0)
+#define trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
#endif /* #else #ifdef CONFIG_RCU_TRACE */
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index ca0d23b..34a02da 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -316,3 +316,13 @@ struct debug_obj_descr rcuhead_debug_descr = {
};
EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
#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)
+{
+ trace_rcu_torture_read(rcutorturename, rhp);
+}
+EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
+#else
+#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#endif
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 764825c..df35228 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -913,6 +913,18 @@ rcu_torture_fakewriter(void *arg)
return 0;
}
+void rcutorture_trace_dump(void)
+{
+ static atomic_t beenhere = ATOMIC_INIT(0);
+
+ if (atomic_read(&beenhere))
+ return;
+ if (atomic_xchg(&beenhere, 1) != 0)
+ return;
+ do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
+ ftrace_dump(DUMP_ALL);
+}
+
/*
* RCU torture reader from timer handler. Dereferences rcu_torture_current,
* incrementing the corresponding element of the pipeline array. The
@@ -934,6 +946,7 @@ static void rcu_torture_timer(unsigned long unused)
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
srcu_read_lock_held(&srcu_ctl));
+ do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
if (p == NULL) {
/* Leave because rcu_torture_writer is not yet underway */
cur_ops->readunlock(idx);
@@ -951,6 +964,8 @@ static void rcu_torture_timer(unsigned long unused)
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
+ if (pipe_count > 1)
+ rcutorture_trace_dump();
__this_cpu_inc(rcu_torture_count[pipe_count]);
completed = cur_ops->completed() - completed;
if (completed > RCU_TORTURE_PIPE_LEN) {
@@ -994,6 +1009,7 @@ rcu_torture_reader(void *arg)
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
srcu_read_lock_held(&srcu_ctl));
+ do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
cur_ops->readunlock(idx);
@@ -1009,6 +1025,8 @@ rcu_torture_reader(void *arg)
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
+ if (pipe_count > 1)
+ rcutorture_trace_dump();
__this_cpu_inc(rcu_torture_count[pipe_count]);
completed = cur_ops->completed() - completed;
if (completed > RCU_TORTURE_PIPE_LEN) {
--
1.7.3.2
--
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