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rcu: Add failure tracing to rcutorture 

Trace the rcutorture RCU accesses and dump the trace buffer when the
first failure is detected.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2011-10-02 07:44:32 -07:00 committed by Paul E. McKenney
parent a8eecf2248
commit 91afaf3002
4 changed files with 62 additions and 0 deletions
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8
include/linux/rcupdate.h
View File

@ -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))

26
include/trace/events/rcu.h
View File

@ -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 */

10
kernel/rcupdate.c
View File

@ -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

18
kernel/rcutorture.c
View File

@ -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) {