The patch titled
kernel/timer.c: use debugobjects to catch deletion of uninitialized timers
has been added to the -mm tree. Its filename is
kernel-timerc-use-debugobjects-to-catch-deletion-of-uninitialized-timers.patch
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------------------------------------------------------
Subject: kernel/timer.c: use debugobjects to catch deletion of uninitialized timers
From: Christine Chan <cschan@xxxxxxxxxxxxxx>
del_timer_sync() calls debug_object_assert_init() to assert that a timer
has been initialized before calling lock_timer_base(). lock_timer_base()
would spin forever on a NULL(uninit-ed) base. The check is added to
del_timer() to prevent silent failure, even though it would not get stuck
in an infinite loop.
Signed-off-by: Christine Chan <cschan@xxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/timer.c | 54 ++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 49 insertions(+), 5 deletions(-)
diff -puN kernel/timer.c~kernel-timerc-use-debugobjects-to-catch-deletion-of-uninitialized-timers kernel/timer.c
--- a/kernel/timer.c~kernel-timerc-use-debugobjects-to-catch-deletion-of-uninitialized-timers
+++ a/kernel/timer.c
@@ -480,12 +480,41 @@ static int timer_fixup_free(void *addr,
}
}
+/*
+ * fixup_assert_init is called when:
+ * - an untracked/uninit-ed object is found
+ */
+static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)
+{
+ struct timer_list *timer = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_NOTAVAILABLE:
+ if (timer->entry.prev == TIMER_ENTRY_STATIC) {
+ /*
+ * This is not really a fixup. The timer was
+ * statically initialized. We just make sure that it
+ * is tracked in the object tracker.
+ */
+ debug_object_init(timer, &timer_debug_descr);
+ return 0;
+ } else {
+ WARN_ON(1);
+ init_timer(timer);
+ return 1;
+ }
+ default:
+ return 0;
+ }
+}
+
static struct debug_obj_descr timer_debug_descr = {
- .name = "timer_list",
- .debug_hint = timer_debug_hint,
- .fixup_init = timer_fixup_init,
- .fixup_activate = timer_fixup_activate,
- .fixup_free = timer_fixup_free,
+ .name = "timer_list",
+ .debug_hint = timer_debug_hint,
+ .fixup_init = timer_fixup_init,
+ .fixup_activate = timer_fixup_activate,
+ .fixup_free = timer_fixup_free,
+ .fixup_assert_init = timer_fixup_assert_init,
};
static inline void debug_timer_init(struct timer_list *timer)
@@ -508,6 +537,11 @@ static inline void debug_timer_free(stru
debug_object_free(timer, &timer_debug_descr);
}
+static inline void debug_timer_assert_init(struct timer_list *timer)
+{
+ debug_object_assert_init(timer, &timer_debug_descr);
+}
+
static void __init_timer(struct timer_list *timer,
const char *name,
struct lock_class_key *key);
@@ -531,6 +565,7 @@ EXPORT_SYMBOL_GPL(destroy_timer_on_stack
static inline void debug_timer_init(struct timer_list *timer) { }
static inline void debug_timer_activate(struct timer_list *timer) { }
static inline void debug_timer_deactivate(struct timer_list *timer) { }
+static inline void debug_timer_assert_init(struct timer_list *timer) { }
#endif
static inline void debug_init(struct timer_list *timer)
@@ -552,6 +587,11 @@ static inline void debug_deactivate(stru
trace_timer_cancel(timer);
}
+static inline void debug_assert_init(struct timer_list *timer)
+{
+ debug_timer_assert_init(timer);
+}
+
static void __init_timer(struct timer_list *timer,
const char *name,
struct lock_class_key *key)
@@ -902,6 +942,8 @@ int del_timer(struct timer_list *timer)
unsigned long flags;
int ret = 0;
+ debug_assert_init(timer);
+
timer_stats_timer_clear_start_info(timer);
if (timer_pending(timer)) {
base = lock_timer_base(timer, &flags);
@@ -932,6 +974,8 @@ int try_to_del_timer_sync(struct timer_l
unsigned long flags;
int ret = -1;
+ debug_assert_init(timer);
+
base = lock_timer_base(timer, &flags);
if (base->running_timer == timer)
_
Patches currently in -mm which might be from cschan@xxxxxxxxxxxxxx are
debugobjects-extend-debugobjects-to-assert-that-an-object-is-initialized.patch
kernel-timerc-use-debugobjects-to-catch-deletion-of-uninitialized-timers.patch
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