[Kernel] wakelock debug patch

[crash-utility] wakelock 디버깅(rbtree: wakelocks_tree)

[crash-utility]wakelock - rbtree debugging(디버깅) 

[리눅스커널][Trace32] wakelock 디버깅 - container_of

[Kernel] wakelock debug patch 

안드로이드에서 wake lock이란 기능이 있습니다. 그런데 대부분 wake lock을 어떤 모듈이 잡고 있어서 슬립에 못 들어가는 문제가 생기죠. 이럴 때 프로파일링하면 좋은 디버그 패치를 소개합니다.

diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c

old mode 100644

new mode 100755

index 7dbfe1a..2ca0964

--- a/drivers/base/power/wakeup.c

+++ b/drivers/base/power/wakeup.c

@@ -54,6 +54,7 @@ static DEFINE_SPINLOCK(events_lock);

 static void pm_wakeup_timer_fn(unsigned long data);

 

 static LIST_HEAD(wakeup_sources);

+static LIST_HEAD(wakeup_sources_shadow);

 

 static DECLARE_WAIT_QUEUE_HEAD(wakeup_count_wait_queue);

 

@@ -134,6 +135,17 @@ static void wakeup_source_destroy_cb(struct rcu_head *head)

  wakeup_source_destroy(container_of(head, struct wakeup_source, rcu));

 }

 

+struct wakeup_source_shadow {

+ struct list_head entry;

+ const char *name;

+ struct task_struct *p;

+ struct wakeup_source *ws;

+ ktime_t add_ts;

+ ktime_t rmv_ts;

+ int ws_event; /* 1 for add, 2 for remove */

+}; 

+

+

 /**

  * wakeup_source_add - Add given object to the list of wakeup sources.

  * @ws: Wakeup source object to add to the list.

@@ -141,7 +153,8 @@ static void wakeup_source_destroy_cb(struct rcu_head *head)

 void wakeup_source_add(struct wakeup_source *ws)

 {

  unsigned long flags;

-

+ struct wakeup_source_shadow *ws_sh;

+

  if (WARN_ON(!ws))

  return;

 

@@ -152,6 +165,19 @@ void wakeup_source_add(struct wakeup_source *ws)

 

  spin_lock_irqsave(&events_lock, flags);

  list_add_rcu(&ws->entry, &wakeup_sources);

+ if (!strncmp(ws->name, "wlan", strlen("wlan"))) {

+ pr_err("[%s] add hit : %p, %s\n", __func__, ws, ws->name);

+ ws_sh = kmalloc(sizeof(*ws_sh), GFP_ATOMIC);

+ if (ws_sh) {

+ ws_sh->ws = ws;

+ ws_sh->p = current;

+ ws_sh->name = ws->name;

+ ws_sh->add_ts = ws_sh->rmv_ts = ws->last_time;

+ ws_sh->ws_event = 1;

+ list_add_rcu(&ws_sh->entry, &wakeup_sources_shadow);

+ dump_stack();

+ }

+ }

  spin_unlock_irqrestore(&events_lock, flags);

 }

 EXPORT_SYMBOL_GPL(wakeup_source_add);

@@ -163,12 +189,25 @@ EXPORT_SYMBOL_GPL(wakeup_source_add);

 void wakeup_source_remove(struct wakeup_source *ws)

 {

  unsigned long flags;

-

+ struct wakeup_source_shadow *ws_sh;

+

  if (WARN_ON(!ws))

  return;

 

  spin_lock_irqsave(&events_lock, flags);

  list_del_rcu(&ws->entry);

+ if (!strncmp(ws->name, "wlan", strlen("wlan"))) {

+ pr_err("[%s] rmv hit : %p, %s\n", __func__, ws, ws->name);

+ list_for_each_entry(ws_sh, &wakeup_sources_shadow, entry) {

+ if (ws_sh->ws == ws) {

+ ws_sh->rmv_ts = ktime_get();

+ ws_sh->ws_event = 2;

+ ws_sh->p = current;

+ dump_stack();

+ break;

+ }

+ }

+ }

  spin_unlock_irqrestore(&events_lock, flags);

  synchronize_rcu();

 }