[PATCH tip/core/rcu 16/86] rcu: make rcutorture version numbers available through debugfs

Paul E. McKenney
2011-05-01T13:36:51Z

From: Paul E. McKenney <paul.mckenney@linaro.org>

It is not possible to accurately correlate rcutorture output with that
of debugfs. This patch therefore adds a debugfs file that prints out
the rcutorture version number, permitting easy correlation.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcupdate.h | 13 ++++++++++++-
include/linux/rcutree.h | 3 +++
kernel/rcutorture.c | 8 +++++---
kernel/rcutree.c | 37 +++++++++++++++++++++++++++++++++++++
kernel/rcutree_trace.c | 28 ++++++++++++++++++++++++++++
5 files changed, 85 insertions(+), 4 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index ff422d2..9e169c2 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -47,6 +47,18 @@
extern int rcutorture_runnable; /* for sysctl */
#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */

+#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);
+#else
+static inline void rcutorture_record_test_transition(void)
+{
+}
+static inline void rcutorture_record_progress(unsigned long vernum)
+{
+}
+#endif
+
#define UINT_CMP_GE(a, b) (UINT_MAX / 2 >= (a) - (b))
#define UINT_CMP_LT(a, b) (UINT_MAX / 2 < (a) - (b))
#define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b))
@@ -68,7 +80,6 @@ extern void call_rcu_sched(struct rcu_head *head,
extern void synchronize_sched(void);
extern void rcu_barrier_bh(void);
extern void rcu_barrier_sched(void);
-extern int sched_expedited_torture_stats(char *page);

static inline void __rcu_read_lock_bh(void)
{
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 3a93348..284dad1 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -58,9 +58,12 @@ static inline void synchronize_rcu_bh_expedited(void)

extern void rcu_barrier(void);

+extern unsigned long rcutorture_testseq;
+extern unsigned long rcutorture_vernum;
extern long rcu_batches_completed(void);
extern long rcu_batches_completed_bh(void);
extern long rcu_batches_completed_sched(void);
+
extern void rcu_force_quiescent_state(void);
extern void rcu_bh_force_quiescent_state(void);
extern void rcu_sched_force_quiescent_state(void);
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 62ec8ee6..735d172 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -131,7 +131,7 @@ struct rcu_torture {

static LIST_HEAD(rcu_torture_freelist);
static struct rcu_torture __rcu *rcu_torture_current;
-static long rcu_torture_current_version;
+static unsigned long rcu_torture_current_version;
static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
static DEFINE_SPINLOCK(rcu_torture_lock);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
@@ -886,7 +886,7 @@ rcu_torture_writer(void *arg)
old_rp->rtort_pipe_count++;
cur_ops->deferred_free(old_rp);
}
- rcu_torture_current_version++;
+ rcutorture_record_progress(++rcu_torture_current_version);
oldbatch = cur_ops->completed();
rcu_stutter_wait("rcu_torture_writer");
} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
@@ -1066,7 +1066,7 @@ rcu_torture_printk(char *page)
}
cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
cnt += sprintf(&page[cnt],
- "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
+ "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
"rtmbe: %d rtbke: %ld rtbre: %ld "
"rtbf: %ld rtb: %ld nt: %ld",
rcu_torture_current,
@@ -1329,6 +1329,7 @@ rcu_torture_cleanup(void)
int i;

mutex_lock(&fullstop_mutex);
+ rcutorture_record_test_transition();
if (fullstop == FULLSTOP_SHUTDOWN) {
printk(KERN_WARNING /* but going down anyway, so... */
"Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
@@ -1622,6 +1623,7 @@ rcu_torture_init(void)
}
}
register_reboot_notifier(&rcutorture_shutdown_nb);
+ rcutorture_record_test_transition();
mutex_unlock(&fullstop_mutex);
return 0;

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index a591694..c1f5434 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -102,6 +102,18 @@ static void invoke_rcu_cpu_kthread(void);
#define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */

/*
+ * Track the rcutorture test sequence number and the update version
+ * number within a given test. The rcutorture_testseq is incremented
+ * on every rcutorture module load and unload, so has an odd value
+ * when a test is running. The rcutorture_vernum is set to zero
+ * when rcutorture starts and is incremented on each rcutorture update.
+ * These variables enable correlating rcutorture output with the
+ * RCU tracing information.
+ */
+unsigned long rcutorture_testseq;
+unsigned long rcutorture_vernum;
+
+/*
* Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
* permit this function to be invoked without holding the root rcu_node
* structure's ->lock, but of course results can be subject to change.
@@ -193,6 +205,31 @@ void rcu_bh_force_quiescent_state(void)
EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);

/*
+ * Record the number of times rcutorture tests have been initiated and
+ * terminated. This information allows the debugfs tracing stats to be
+ * correlated to the rcutorture messages, even when the rcutorture module
+ * is being repeatedly loaded and unloaded. In other words, we cannot
+ * store this state in rcutorture itself.
+ */
+void rcutorture_record_test_transition(void)
+{
+ rcutorture_testseq++;
+ rcutorture_vernum = 0;
+}
+EXPORT_SYMBOL_GPL(rcutorture_record_test_transition);
+
+/*
+ * Record the number of writer passes through the current rcutorture test.
+ * This is also used to correlate debugfs tracing stats with the rcutorture
+ * messages.
+ */
+void rcutorture_record_progress(unsigned long vernum)
+{
+ rcutorture_vernum++;
+}
+EXPORT_SYMBOL_GPL(rcutorture_record_progress);
+
+/*
* Force a quiescent state for RCU-sched.
*/
void rcu_sched_force_quiescent_state(void)
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index fc40e89..3baa235 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -394,6 +394,29 @@ static const struct file_operations rcu_pending_fops = {
.release = single_release,
};

+static int show_rcutorture(struct seq_file *m, void *unused)
+{
+ seq_printf(m, "rcutorture test sequence: %lu %s\n",
+ rcutorture_testseq >> 1,
+ (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
+ seq_printf(m, "rcutorture update version number: %lu\n",
+ rcutorture_vernum);
+ return 0;
+}
+
+static int rcutorture_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_rcutorture, NULL);
+}
+
+static const struct file_operations rcutorture_fops = {
+ .owner = THIS_MODULE,
+ .open = rcutorture_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
static struct dentry *rcudir;

static int __init rcutree_trace_init(void)
@@ -430,6 +453,11 @@ static int __init rcutree_trace_init(void)
NULL, &rcu_pending_fops);
if (!retval)
goto free_out;
+
+ retval = debugfs_create_file("rcutorture", 0444, rcudir,
+ NULL, &rcutorture_fops);
+ if (!retval)
+ goto free_out;
return 0;
free_out:
debugfs_remove_recursive(rcudir);
--
1.7.3.2