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Date: Mon, 28 Apr 2014 17:24:49 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, laijs@...fujitsu.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
peterz@...radead.org, rostedt@...dmis.org, dhowells@...hat.com,
edumazet@...gle.com, darren@...art.com, fweisbec@...il.com,
oleg@...hat.com, sbw@....edu,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 01/45] rcutorture: Add forward-progress checking for writer
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
The rcutorture output currently does not distinguish between stalls in
the RCU implementation and stalls in the rcu_torture_writer() kthreads.
This commit therefore adds some diagnostics to help distinguish between
these two conditions, at least for the non-SRCU implementations. (SRCU
does not provide evidence of update-side forward progress by design.)
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
include/linux/rcupdate.h | 19 +++++++++++++++++++
kernel/rcu/rcutorture.c | 37 +++++++++++++++++++++++++++++++++++++
kernel/rcu/tree.c | 18 ++++++++++++++++++
3 files changed, 74 insertions(+)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 00a7fd61b3c6..a6c3898e141e 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -51,7 +51,17 @@ extern int rcu_expedited; /* for sysctl */
extern int rcutorture_runnable; /* for sysctl */
#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
+enum rcutorture_type {
+ RTORT_BUSTED,
+ RTORT_RCU,
+ RTORT_RCU_BH,
+ RTORT_RCU_SCHED,
+ RTORT_SRCU
+};
+
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
+void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
+ unsigned long *gpnum, unsigned long *completed);
void rcutorture_record_test_transition(void);
void rcutorture_record_progress(unsigned long vernum);
void do_trace_rcu_torture_read(const char *rcutorturename,
@@ -60,6 +70,15 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
unsigned long c_old,
unsigned long c);
#else
+static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
+ int *flags,
+ unsigned long *gpnum,
+ unsigned long *completed)
+{
+ *flags = 0;
+ *gpnum = 0;
+ *completed = 0;
+}
static inline void rcutorture_record_test_transition(void)
{
}
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index bd30bc61bc05..1110db210318 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -138,6 +138,15 @@ static long n_barrier_attempts;
static long n_barrier_successes;
static struct list_head rcu_torture_removed;
+static int rcu_torture_writer_state;
+#define RTWS_FIXED_DELAY 0
+#define RTWS_DELAY 1
+#define RTWS_REPLACE 2
+#define RTWS_DEF_FREE 3
+#define RTWS_EXP_SYNC 4
+#define RTWS_STUTTER 5
+#define RTWS_STOPPING 6
+
#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
#define RCUTORTURE_RUNNABLE_INIT 1
#else
@@ -214,6 +223,7 @@ rcu_torture_free(struct rcu_torture *p)
*/
struct rcu_torture_ops {
+ int ttype;
void (*init)(void);
int (*readlock)(void);
void (*read_delay)(struct torture_random_state *rrsp);
@@ -312,6 +322,7 @@ static void rcu_sync_torture_init(void)
}
static struct rcu_torture_ops rcu_ops = {
+ .ttype = RTORT_RCU,
.init = rcu_sync_torture_init,
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay,
@@ -355,6 +366,7 @@ static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
}
static struct rcu_torture_ops rcu_bh_ops = {
+ .ttype = RTORT_RCU_BH,
.init = rcu_sync_torture_init,
.readlock = rcu_bh_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
@@ -397,6 +409,7 @@ call_rcu_busted(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
}
static struct rcu_torture_ops rcu_busted_ops = {
+ .ttype = RTORT_BUSTED,
.init = rcu_sync_torture_init,
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
@@ -492,6 +505,7 @@ static void srcu_torture_synchronize_expedited(void)
}
static struct rcu_torture_ops srcu_ops = {
+ .ttype = RTORT_SRCU,
.init = rcu_sync_torture_init,
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
@@ -527,6 +541,7 @@ static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
}
static struct rcu_torture_ops sched_ops = {
+ .ttype = RTORT_RCU_SCHED,
.init = rcu_sync_torture_init,
.readlock = sched_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
@@ -699,12 +714,15 @@ rcu_torture_writer(void *arg)
set_user_nice(current, MAX_NICE);
do {
+ rcu_torture_writer_state = RTWS_FIXED_DELAY;
schedule_timeout_uninterruptible(1);
rp = rcu_torture_alloc();
if (rp == NULL)
continue;
rp->rtort_pipe_count = 0;
+ rcu_torture_writer_state = RTWS_DELAY;
udelay(torture_random(&rand) & 0x3ff);
+ rcu_torture_writer_state = RTWS_REPLACE;
old_rp = rcu_dereference_check(rcu_torture_current,
current == writer_task);
rp->rtort_mbtest = 1;
@@ -721,8 +739,10 @@ rcu_torture_writer(void *arg)
else
exp = gp_exp;
if (!exp) {
+ rcu_torture_writer_state = RTWS_DEF_FREE;
cur_ops->deferred_free(old_rp);
} else {
+ rcu_torture_writer_state = RTWS_EXP_SYNC;
cur_ops->exp_sync();
list_add(&old_rp->rtort_free,
&rcu_torture_removed);
@@ -743,8 +763,10 @@ rcu_torture_writer(void *arg)
}
}
rcutorture_record_progress(++rcu_torture_current_version);
+ rcu_torture_writer_state = RTWS_STUTTER;
stutter_wait("rcu_torture_writer");
} while (!torture_must_stop());
+ rcu_torture_writer_state = RTWS_STOPPING;
torture_kthread_stopping("rcu_torture_writer");
return 0;
}
@@ -937,6 +959,7 @@ rcu_torture_printk(char *page)
int i;
long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
+ static unsigned long rtcv_snap = ULONG_MAX;
for_each_possible_cpu(cpu) {
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
@@ -997,6 +1020,20 @@ rcu_torture_printk(char *page)
page += sprintf(page, "\n");
if (cur_ops->stats)
cur_ops->stats(page);
+ if (rtcv_snap == rcu_torture_current_version &&
+ rcu_torture_current != NULL) {
+ int __maybe_unused flags;
+ unsigned long __maybe_unused gpnum;
+ unsigned long __maybe_unused completed;
+
+ rcutorture_get_gp_data(cur_ops->ttype,
+ &flags, &gpnum, &completed);
+ page += sprintf(page,
+ "??? Writer stall state %d g%lu c%lu f%#x\n",
+ rcu_torture_writer_state,
+ gpnum, completed, flags);
+ }
+ rtcv_snap = rcu_torture_current_version;
}
/*
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 0c47e300210a..032106df7391 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -294,6 +294,24 @@ void rcutorture_record_test_transition(void)
EXPORT_SYMBOL_GPL(rcutorture_record_test_transition);
/*
+ * Send along grace-period-related data for rcutorture diagnostics.
+ */
+void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
+ unsigned long *gpnum, unsigned long *completed)
+{
+ if (test_type == RTORT_SRCU || test_type == RTORT_BUSTED) {
+ *flags = 0;
+ *gpnum = 0;
+ *completed = 0;
+ return;
+ }
+ *flags = ACCESS_ONCE(rcu_state->gp_flags);
+ *gpnum = ACCESS_ONCE(rcu_state->gpnum);
+ *completed = ACCESS_ONCE(rcu_state->completed);
+}
+EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
+
+/*
* Record the number of writer passes through the current rcutorture test.
* This is also used to correlate debugfs tracing stats with the rcutorture
* messages.
--
1.8.1.5
--
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