Commit b84d435c authored by Christine Chan's avatar Christine Chan Committed by Thomas Gleixner

debugobjects: Extend to assert that an object is initialized

Calling del_timer_sync() on an uninitialized timer leads to a
never ending loop in lock_timer_base() that spins checking for a
non-NULL timer base. Add an assertion to debugobjects to catch
usage of uninitialized objects so that we can initialize timers
in the del_timer_sync() path before it calls lock_timer_base().

[ [email protected]: Clarify commit message ]
Signed-off-by: default avatarChristine Chan <[email protected]>
Signed-off-by: default avatarStephen Boyd <[email protected]>
Cc: John Stultz <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]Signed-off-by: default avatarAndrew Morton <[email protected]>
Signed-off-by: default avatarThomas Gleixner <[email protected]>
parent feac18dd
......@@ -96,6 +96,7 @@
<listitem><para>debug_object_deactivate</para></listitem>
<listitem><para>debug_object_destroy</para></listitem>
<listitem><para>debug_object_free</para></listitem>
<listitem><para>debug_object_assert_init</para></listitem>
</itemizedlist>
Each of these functions takes the address of the real object and
a pointer to the object type specific debug description
......@@ -273,6 +274,26 @@
debug checks.
</para>
</sect1>
<sect1 id="debug_object_assert_init">
<title>debug_object_assert_init</title>
<para>
This function is called to assert that an object has been
initialized.
</para>
<para>
When the real object is not tracked by debugobjects, it calls
fixup_assert_init of the object type description structure
provided by the caller, with the hardcoded object state
ODEBUG_NOT_AVAILABLE. The fixup function can correct the problem
by calling debug_object_init and other specific initializing
functions.
</para>
<para>
When the real object is already tracked by debugobjects it is
ignored.
</para>
</sect1>
</chapter>
<chapter id="fixupfunctions">
<title>Fixup functions</title>
......@@ -381,6 +402,35 @@
statistics.
</para>
</sect1>
<sect1 id="fixup_assert_init">
<title>fixup_assert_init</title>
<para>
This function is called from the debug code whenever a problem
in debug_object_assert_init is detected.
</para>
<para>
Called from debug_object_assert_init() with a hardcoded state
ODEBUG_STATE_NOTAVAILABLE when the object is not found in the
debug bucket.
</para>
<para>
The function returns 1 when the fixup was successful,
otherwise 0. The return value is used to update the
statistics.
</para>
<para>
Note, this function should make sure debug_object_init() is
called before returning.
</para>
<para>
The handling of statically initialized objects is a special
case. The fixup function should check if this is a legitimate
case of a statically initialized object or not. In this case only
debug_object_init() should be called to make the object known to
the tracker. Then the function should return 0 because this is not
a real fixup.
</para>
</sect1>
</chapter>
<chapter id="bugs">
<title>Known Bugs And Assumptions</title>
......
......@@ -46,6 +46,8 @@ struct debug_obj {
* fails
* @fixup_free: fixup function, which is called when the free check
* fails
* @fixup_assert_init: fixup function, which is called when the assert_init
* check fails
*/
struct debug_obj_descr {
const char *name;
......@@ -54,6 +56,7 @@ struct debug_obj_descr {
int (*fixup_activate) (void *addr, enum debug_obj_state state);
int (*fixup_destroy) (void *addr, enum debug_obj_state state);
int (*fixup_free) (void *addr, enum debug_obj_state state);
int (*fixup_assert_init)(void *addr, enum debug_obj_state state);
};
#ifdef CONFIG_DEBUG_OBJECTS
......@@ -64,6 +67,7 @@ extern void debug_object_activate (void *addr, struct debug_obj_descr *descr);
extern void debug_object_deactivate(void *addr, struct debug_obj_descr *descr);
extern void debug_object_destroy (void *addr, struct debug_obj_descr *descr);
extern void debug_object_free (void *addr, struct debug_obj_descr *descr);
extern void debug_object_assert_init(void *addr, struct debug_obj_descr *descr);
/*
* Active state:
......@@ -89,6 +93,8 @@ static inline void
debug_object_destroy (void *addr, struct debug_obj_descr *descr) { }
static inline void
debug_object_free (void *addr, struct debug_obj_descr *descr) { }
static inline void
debug_object_assert_init(void *addr, struct debug_obj_descr *descr) { }
static inline void debug_objects_early_init(void) { }
static inline void debug_objects_mem_init(void) { }
......
......@@ -570,6 +570,44 @@ void debug_object_free(void *addr, struct debug_obj_descr *descr)
raw_spin_unlock_irqrestore(&db->lock, flags);
}
/**
* debug_object_assert_init - debug checks when object should be init-ed
* @addr: address of the object
* @descr: pointer to an object specific debug description structure
*/
void debug_object_assert_init(void *addr, struct debug_obj_descr *descr)
{
struct debug_bucket *db;
struct debug_obj *obj;
unsigned long flags;
if (!debug_objects_enabled)
return;
db = get_bucket((unsigned long) addr);
raw_spin_lock_irqsave(&db->lock, flags);
obj = lookup_object(addr, db);
if (!obj) {
struct debug_obj o = { .object = addr,
.state = ODEBUG_STATE_NOTAVAILABLE,
.descr = descr };
raw_spin_unlock_irqrestore(&db->lock, flags);
/*
* Maybe the object is static. Let the type specific
* code decide what to do.
*/
if (debug_object_fixup(descr->fixup_assert_init, addr,
ODEBUG_STATE_NOTAVAILABLE))
debug_print_object(&o, "assert_init");
return;
}
raw_spin_unlock_irqrestore(&db->lock, flags);
}
/**
* debug_object_active_state - debug checks object usage state machine
* @addr: address of the object
......
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