We encounted one BUG_ON() issue at function __run_hrtimer(),
but the panic info is not enough to find out which hrtimer
users use the hrtimer wrongly.
(in this BUG_ON case, it is callback running at the same time
hrtimer_start() is executed on different context.)
We can print basic timer info before BUG(), it is easy to find
out which hrtimer user has fault, the output info is like below:
<3>[ 41.118552] timer info: state/3, func/test_timer_cb
<3>[ 41.118618] timer stats: pid/786(sh), site/hrtimer_start
<0>[ 41.118670] ------------[ cut here ]------------
<2>[ 41.118691] kernel BUG at
/root/r4_code/hardware/intel/linux-2.6/kernel/hrtimer.c:1260!
<0>[ 41.118715] invalid opcode: 0000 [#1] PREEMPT SMP
The infos of callback/state are very helpful for debugging this BUG_ON().
Signed-off-by: Li Fei <fei...@intel.com>
Signed-off-by: liu chuansheng <chuansheng....@intel.com>
---
kernel/hrtimer.c | 34 +++++++++++++++++++++++++++++++++-
1 files changed, 33 insertions(+), 1 deletions(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 6db7a5e..388e8b2 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1204,6 +1204,35 @@ int hrtimer_get_res(const clockid_t which_clock, struct
timespec *tp)
}
EXPORT_SYMBOL_GPL(hrtimer_get_res);
+/*
+ * dump_hrtimer_callinfo - print hrtimer information including:
+ * state, callback function, pid and start_site.
+*/
+static void dump_hrtimer_callinfo(struct hrtimer *timer)
+{
+
+ char symname[KSYM_NAME_LEN];
+
+ if (lookup_symbol_name((unsigned long)(timer->function), symname) < 0) {
+ pr_err("timer info: state/%lx, func/%pK\n",
+ timer->state, timer->function);
+ } else {
+ pr_err("timer info: state/%lx, func/%s",
+ timer->state, symname);
+ }
+
+#ifdef CONFIG_TIMER_STATS
+ if (lookup_symbol_name((unsigned long)(timer->start_site),
+ symname) < 0) {
+ pr_err("timer stats: pid/%d(%s), site/%pK\n",
+ timer->start_pid, timer->start_comm, timer->start_site);
+ } else {
+ pr_err("timer stats: pid/%d(%s), site/%s\n",
+ timer->start_pid, timer->start_comm, symname);
+ }
+#endif
+}
+
static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
{
struct hrtimer_clock_base *base = timer->base;
@@ -1235,7 +1264,10 @@ static void __run_hrtimer(struct hrtimer *timer, ktime_t
*now)
* hrtimer_start_range_ns() or in hrtimer_interrupt()
*/
if (restart != HRTIMER_NORESTART) {
- BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
+ if (timer->state != HRTIMER_STATE_CALLBACK) {
+ dump_hrtimer_callinfo(timer);
+ BUG();
+ }
enqueue_hrtimer(timer, base);
}
--
1.7.0.4
--
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