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forked fromtorvalds/linux

Commit6f2b9b9

Browse files
jmbergIngo Molnar
authored and
Ingo Molnar
committed
timer: implement lockdep deadlock detection
This modifies the timer code in a way to allow lockdep to detectdeadlocks resulting from a lock being taken in the timer functionas well as around the del_timer_sync() call.Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
1 parent673f820 commit6f2b9b9

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2 files changed

+141
-20
lines changed

2 files changed

+141
-20
lines changed

‎include/linux/timer.h‎

Lines changed: 84 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@
55
#include<linux/ktime.h>
66
#include<linux/stddef.h>
77
#include<linux/debugobjects.h>
8+
#include<linux/stringify.h>
89

910
structtvec_base;
1011

@@ -21,52 +22,126 @@ struct timer_list {
2122
charstart_comm[16];
2223
intstart_pid;
2324
#endif
25+
#ifdefCONFIG_LOCKDEP
26+
structlockdep_maplockdep_map;
27+
#endif
2428
};
2529

2630
externstructtvec_baseboot_tvec_bases;
2731

32+
#ifdefCONFIG_LOCKDEP
33+
/*
34+
* NB: because we have to copy the lockdep_map, setting the lockdep_map key
35+
* (second argument) here is required, otherwise it could be initialised to
36+
* the copy of the lockdep_map later! We use the pointer to and the string
37+
* "<file>:<line>" as the key resp. the name of the lockdep_map.
38+
*/
39+
#define__TIMER_LOCKDEP_MAP_INITIALIZER(_kn)\
40+
.lockdep_map = STATIC_LOCKDEP_MAP_INIT(_kn, &_kn),
41+
#else
42+
#define__TIMER_LOCKDEP_MAP_INITIALIZER(_kn)
43+
#endif
44+
2845
#defineTIMER_INITIALIZER(_function,_expires,_data) {\
2946
.entry = { .prev = TIMER_ENTRY_STATIC },\
3047
.function = (_function),\
3148
.expires = (_expires),\
3249
.data = (_data),\
3350
.base = &boot_tvec_bases,\
51+
__TIMER_LOCKDEP_MAP_INITIALIZER(\
52+
__FILE__ ":" __stringify(__LINE__))\
3453
}
3554

3655
#defineDEFINE_TIMER(_name,_function,_expires,_data)\
3756
struct timer_list _name =\
3857
TIMER_INITIALIZER(_function, _expires, _data)
3958

40-
voidinit_timer(structtimer_list*timer);
41-
voidinit_timer_deferrable(structtimer_list*timer);
59+
voidinit_timer_key(structtimer_list*timer,
60+
constchar*name,
61+
structlock_class_key*key);
62+
voidinit_timer_deferrable_key(structtimer_list*timer,
63+
constchar*name,
64+
structlock_class_key*key);
65+
66+
#ifdefCONFIG_LOCKDEP
67+
#defineinit_timer(timer)\
68+
do {\
69+
static struct lock_class_key __key;\
70+
init_timer_key((timer), #timer, &__key);\
71+
} while (0)
72+
73+
#defineinit_timer_deferrable(timer)\
74+
do {\
75+
static struct lock_class_key __key;\
76+
init_timer_deferrable_key((timer), #timer, &__key);\
77+
} while (0)
78+
79+
#defineinit_timer_on_stack(timer)\
80+
do {\
81+
static struct lock_class_key __key;\
82+
init_timer_on_stack_key((timer), #timer, &__key);\
83+
} while (0)
84+
85+
#definesetup_timer(timer,fn,data)\
86+
do {\
87+
static struct lock_class_key __key;\
88+
setup_timer_key((timer), #timer, &__key, (fn), (data));\
89+
} while (0)
90+
91+
#definesetup_timer_on_stack(timer,fn,data)\
92+
do {\
93+
static struct lock_class_key __key;\
94+
setup_timer_on_stack_key((timer), #timer, &__key,\
95+
(fn), (data));\
96+
} while (0)
97+
#else
98+
#defineinit_timer(timer)\
99+
init_timer_key((timer), NULL, NULL)
100+
#defineinit_timer_deferrable(timer)\
101+
init_timer_deferrable_key((timer), NULL, NULL)
102+
#defineinit_timer_on_stack(timer)\
103+
init_timer_on_stack_key((timer), NULL, NULL)
104+
#definesetup_timer(timer,fn,data)\
105+
setup_timer_key((timer), NULL, NULL, (fn), (data))
106+
#definesetup_timer_on_stack(timer,fn,data)\
107+
setup_timer_on_stack_key((timer), NULL, NULL, (fn), (data))
108+
#endif
42109

43110
#ifdefCONFIG_DEBUG_OBJECTS_TIMERS
44-
externvoidinit_timer_on_stack(structtimer_list*timer);
111+
externvoidinit_timer_on_stack_key(structtimer_list*timer,
112+
constchar*name,
113+
structlock_class_key*key);
45114
externvoiddestroy_timer_on_stack(structtimer_list*timer);
46115
#else
47116
staticinlinevoiddestroy_timer_on_stack(structtimer_list*timer) { }
48-
staticinlinevoidinit_timer_on_stack(structtimer_list*timer)
117+
staticinlinevoidinit_timer_on_stack_key(structtimer_list*timer,
118+
constchar*name,
119+
structlock_class_key*key)
49120
{
50-
init_timer(timer);
121+
init_timer_key(timer,name,key);
51122
}
52123
#endif
53124

54-
staticinlinevoidsetup_timer(structtimer_list*timer,
125+
staticinlinevoidsetup_timer_key(structtimer_list*timer,
126+
constchar*name,
127+
structlock_class_key*key,
55128
void (*function)(unsigned long),
56129
unsigned longdata)
57130
{
58131
timer->function=function;
59132
timer->data=data;
60-
init_timer(timer);
133+
init_timer_key(timer,name,key);
61134
}
62135

63-
staticinlinevoidsetup_timer_on_stack(structtimer_list*timer,
136+
staticinlinevoidsetup_timer_on_stack_key(structtimer_list*timer,
137+
constchar*name,
138+
structlock_class_key*key,
64139
void (*function)(unsigned long),
65140
unsigned longdata)
66141
{
67142
timer->function=function;
68143
timer->data=data;
69-
init_timer_on_stack(timer);
144+
init_timer_on_stack_key(timer,name,key);
70145
}
71146

72147
/**

‎kernel/timer.c‎

Lines changed: 57 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -491,14 +491,18 @@ static inline void debug_timer_free(struct timer_list *timer)
491491
debug_object_free(timer,&timer_debug_descr);
492492
}
493493

494-
staticvoid__init_timer(structtimer_list*timer);
494+
staticvoid__init_timer(structtimer_list*timer,
495+
constchar*name,
496+
structlock_class_key*key);
495497

496-
voidinit_timer_on_stack(structtimer_list*timer)
498+
voidinit_timer_on_stack_key(structtimer_list*timer,
499+
constchar*name,
500+
structlock_class_key*key)
497501
{
498502
debug_object_init_on_stack(timer,&timer_debug_descr);
499-
__init_timer(timer);
503+
__init_timer(timer,name,key);
500504
}
501-
EXPORT_SYMBOL_GPL(init_timer_on_stack);
505+
EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
502506

503507
voiddestroy_timer_on_stack(structtimer_list*timer)
504508
{
@@ -512,7 +516,9 @@ static inline void debug_timer_activate(struct timer_list *timer) { }
512516
staticinlinevoiddebug_timer_deactivate(structtimer_list*timer) { }
513517
#endif
514518

515-
staticvoid__init_timer(structtimer_list*timer)
519+
staticvoid__init_timer(structtimer_list*timer,
520+
constchar*name,
521+
structlock_class_key*key)
516522
{
517523
timer->entry.next=NULL;
518524
timer->base=__raw_get_cpu_var(tvec_bases);
@@ -521,6 +527,7 @@ static void __init_timer(struct timer_list *timer)
521527
timer->start_pid=-1;
522528
memset(timer->start_comm,0,TASK_COMM_LEN);
523529
#endif
530+
lockdep_init_map(&timer->lockdep_map,name,key,0);
524531
}
525532

526533
/**
@@ -530,19 +537,23 @@ static void __init_timer(struct timer_list *timer)
530537
* init_timer() must be done to a timer prior calling *any* of the
531538
* other timer functions.
532539
*/
533-
voidinit_timer(structtimer_list*timer)
540+
voidinit_timer_key(structtimer_list*timer,
541+
constchar*name,
542+
structlock_class_key*key)
534543
{
535544
debug_timer_init(timer);
536-
__init_timer(timer);
545+
__init_timer(timer,name,key);
537546
}
538-
EXPORT_SYMBOL(init_timer);
547+
EXPORT_SYMBOL(init_timer_key);
539548

540-
voidinit_timer_deferrable(structtimer_list*timer)
549+
voidinit_timer_deferrable_key(structtimer_list*timer,
550+
constchar*name,
551+
structlock_class_key*key)
541552
{
542-
init_timer(timer);
553+
init_timer_key(timer,name,key);
543554
timer_set_deferrable(timer);
544555
}
545-
EXPORT_SYMBOL(init_timer_deferrable);
556+
EXPORT_SYMBOL(init_timer_deferrable_key);
546557

547558
staticinlinevoiddetach_timer(structtimer_list*timer,
548559
intclear_pending)
@@ -789,6 +800,15 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
789800
*/
790801
intdel_timer_sync(structtimer_list*timer)
791802
{
803+
#ifdefCONFIG_LOCKDEP
804+
unsigned longflags;
805+
806+
local_irq_save(flags);
807+
lock_map_acquire(&timer->lockdep_map);
808+
lock_map_release(&timer->lockdep_map);
809+
local_irq_restore(flags);
810+
#endif
811+
792812
for (;;) {
793813
intret=try_to_del_timer_sync(timer);
794814
if (ret >=0)
@@ -861,10 +881,36 @@ static inline void __run_timers(struct tvec_base *base)
861881

862882
set_running_timer(base,timer);
863883
detach_timer(timer,1);
884+
864885
spin_unlock_irq(&base->lock);
865886
{
866887
intpreempt_count=preempt_count();
888+
889+
#ifdefCONFIG_LOCKDEP
890+
/*
891+
* It is permissible to free the timer from
892+
* inside the function that is called from
893+
* it, this we need to take into account for
894+
* lockdep too. To avoid bogus "held lock
895+
* freed" warnings as well as problems when
896+
* looking into timer->lockdep_map, make a
897+
* copy and use that here.
898+
*/
899+
structlockdep_maplockdep_map=
900+
timer->lockdep_map;
901+
#endif
902+
/*
903+
* Couple the lock chain with the lock chain at
904+
* del_timer_sync() by acquiring the lock_map
905+
* around the fn() call here and in
906+
* del_timer_sync().
907+
*/
908+
lock_map_acquire(&lockdep_map);
909+
867910
fn(data);
911+
912+
lock_map_release(&lockdep_map);
913+
868914
if (preempt_count!=preempt_count()) {
869915
printk(KERN_ERR"huh, entered %p "
870916
"with preempt_count %08x, exited"

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