[RFC tip/locking/lockdep v5 03/17] lockdep: Redefine LOCK_*_STATE* bits

Boqun Feng
2018-02-22T07:06:07Z

There are three types of lock acquisitions: write, non-recursive read
and recursive read, among which write locks and non-recursive read locks
have no difference from a viewpoint for deadlock detections, because a
write acquisition of the corresponding lock on an independent CPU or
task makes a non-recursive read lock act as a write lock in the sense of
deadlock. So we could treat them as the same type(named as
"non-recursive lock") in lockdep.

As in the irq lock inversion detection(safe->unsafe deadlock detection),
we used to differ write lock with read lock(non-recursive and
recursive ones), such a classification could be improved as
non-recursive read lock behaves the same as write lock, so this patch
redefines the meanings of LOCK_{USED_IN, ENABLED}_STATE*.

old:
LOCK_* : stands for write lock
LOCK_*_READ: stands for read lock(non-recursive and recursive)
new:
LOCK_* : stands for non-recursive(write lock and non-recursive
read lock)
LOCK_*_RR: stands for recursive read lock

Such a change is needed for a future improvement on recursive read
related irq inversion deadlock detection.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
Documentation/locking/lockdep-design.txt | 6 +++---
kernel/locking/lockdep.c | 28 ++++++++++++++--------------
kernel/locking/lockdep_internals.h | 16 ++++++++--------
kernel/locking/lockdep_proc.c | 12 ++++++------
4 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/Documentation/locking/lockdep-design.txt b/Documentation/locking/lockdep-design.txt
index 9de1c158d44c..382bc25589c2 100644
--- a/Documentation/locking/lockdep-design.txt
+++ b/Documentation/locking/lockdep-design.txt
@@ -30,9 +30,9 @@ State
The validator tracks lock-class usage history into 4n + 1 separate state bits:

- 'ever held in STATE context'
-- 'ever held as readlock in STATE context'
+- 'ever held as recursive readlock in STATE context'
- 'ever held with STATE enabled'
-- 'ever held as readlock with STATE enabled'
+- 'ever held as recurisve readlock with STATE enabled'

Where STATE can be either one of (kernel/locking/lockdep_states.h)
- hardirq
@@ -51,7 +51,7 @@ locking error messages, inside curlies. A contrived example:
(&sio_locks[i].lock){-.-...}, at: [<c02867fd>] mutex_lock+0x21/0x24

-The bit position indicates STATE, STATE-read, for each of the states listed
+The bit position indicates STATE, STATE-RR, for each of the states listed
above, and the character displayed in each indicates:

'.' acquired while irqs disabled and not in irq context
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c80f8276ceaa..5e6bf8d6954d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -448,10 +448,10 @@ DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
*/

#define __USAGE(__STATE) \
- [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
- [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
- [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
- [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
+ [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE), \
+ [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON", \
+ [LOCK_USED_IN_##__STATE##_RR] = "IN-"__stringify(__STATE)"-RR", \
+ [LOCK_ENABLED_##__STATE##_RR] = __stringify(__STATE)"-ON-RR",

static const char *usage_str[] =
{
@@ -492,7 +492,7 @@ void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])

#define LOCKDEP_STATE(__STATE) \
usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
- usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
+ usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_RR);
#include "lockdep_states.h"
#undef LOCKDEP_STATE

@@ -1645,7 +1645,7 @@ static const char *state_names[] = {

static const char *state_rnames[] = {
#define LOCKDEP_STATE(__STATE) \
- __stringify(__STATE)"-READ",
+ __stringify(__STATE)"-RR",
#include "lockdep_states.h"
#undef LOCKDEP_STATE
};
@@ -3039,14 +3039,14 @@ static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
* mark the lock as used in these contexts:
*/
if (!hlock->trylock) {
- if (hlock->read) {
+ if (hlock->read == 2) {
if (curr->hardirq_context)
if (!mark_lock(curr, hlock,
- LOCK_USED_IN_HARDIRQ_READ))
+ LOCK_USED_IN_HARDIRQ_RR))
return 0;
if (curr->softirq_context)
if (!mark_lock(curr, hlock,
- LOCK_USED_IN_SOFTIRQ_READ))
+ LOCK_USED_IN_SOFTIRQ_RR))
return 0;
} else {
if (curr->hardirq_context)
@@ -3058,13 +3058,13 @@ static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
}
}
if (!hlock->hardirqs_off) {
- if (hlock->read) {
+ if (hlock->read == 2) {
if (!mark_lock(curr, hlock,
- LOCK_ENABLED_HARDIRQ_READ))
+ LOCK_ENABLED_HARDIRQ_RR))
return 0;
if (curr->softirqs_enabled)
if (!mark_lock(curr, hlock,
- LOCK_ENABLED_SOFTIRQ_READ))
+ LOCK_ENABLED_SOFTIRQ_RR))
return 0;
} else {
if (!mark_lock(curr, hlock,
@@ -3170,9 +3170,9 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
switch (new_bit) {
#define LOCKDEP_STATE(__STATE) \
case LOCK_USED_IN_##__STATE: \
- case LOCK_USED_IN_##__STATE##_READ: \
+ case LOCK_USED_IN_##__STATE##_RR: \
case LOCK_ENABLED_##__STATE: \
- case LOCK_ENABLED_##__STATE##_READ:
+ case LOCK_ENABLED_##__STATE##_RR:
#include "lockdep_states.h"
#undef LOCKDEP_STATE
ret = mark_lock_irq(curr, this, new_bit);
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index d459d624ba2a..93002d337936 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -13,9 +13,9 @@
enum lock_usage_bit {
#define LOCKDEP_STATE(__STATE) \
LOCK_USED_IN_##__STATE, \
- LOCK_USED_IN_##__STATE##_READ, \
+ LOCK_USED_IN_##__STATE##_RR, \
LOCK_ENABLED_##__STATE, \
- LOCK_ENABLED_##__STATE##_READ,
+ LOCK_ENABLED_##__STATE##_RR,
#include "lockdep_states.h"
#undef LOCKDEP_STATE
LOCK_USED,
@@ -30,9 +30,9 @@ enum lock_usage_bit {
enum {
#define LOCKDEP_STATE(__STATE) \
__LOCKF(USED_IN_##__STATE) \
- __LOCKF(USED_IN_##__STATE##_READ) \
+ __LOCKF(USED_IN_##__STATE##_RR) \
__LOCKF(ENABLED_##__STATE) \
- __LOCKF(ENABLED_##__STATE##_READ)
+ __LOCKF(ENABLED_##__STATE##_RR)
#include "lockdep_states.h"
#undef LOCKDEP_STATE
__LOCKF(USED)
@@ -41,10 +41,10 @@ enum {
#define LOCKF_ENABLED_IRQ (LOCKF_ENABLED_HARDIRQ | LOCKF_ENABLED_SOFTIRQ)
#define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)

-#define LOCKF_ENABLED_IRQ_READ \
- (LOCKF_ENABLED_HARDIRQ_READ | LOCKF_ENABLED_SOFTIRQ_READ)
-#define LOCKF_USED_IN_IRQ_READ \
- (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
+#define LOCKF_ENABLED_IRQ_RR \
+ (LOCKF_ENABLED_HARDIRQ_RR | LOCKF_ENABLED_SOFTIRQ_RR)
+#define LOCKF_USED_IN_IRQ_RR \
+ (LOCKF_USED_IN_HARDIRQ_RR | LOCKF_USED_IN_SOFTIRQ_RR)

/*
* CONFIG_LOCKDEP_SMALL is defined for sparc. Sparc requires .text,
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index ad69bbc9bd28..630a6bc6e24c 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -252,17 +252,17 @@ static int lockdep_stats_show(struct seq_file *m, void *v)
nr_hardirq_safe++;
if (class->usage_mask & LOCKF_ENABLED_HARDIRQ)
nr_hardirq_unsafe++;
- if (class->usage_mask & LOCKF_USED_IN_IRQ_READ)
+ if (class->usage_mask & LOCKF_USED_IN_IRQ_RR)
nr_irq_read_safe++;
- if (class->usage_mask & LOCKF_ENABLED_IRQ_READ)
+ if (class->usage_mask & LOCKF_ENABLED_IRQ_RR)
nr_irq_read_unsafe++;
- if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ)
+ if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_RR)
nr_softirq_read_safe++;
- if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_READ)
+ if (class->usage_mask & LOCKF_ENABLED_SOFTIRQ_RR)
nr_softirq_read_unsafe++;
- if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ)
+ if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_RR)
nr_hardirq_read_safe++;
- if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_READ)
+ if (class->usage_mask & LOCKF_ENABLED_HARDIRQ_RR)
nr_hardirq_read_unsafe++;

#ifdef CONFIG_PROVE_LOCKING
--
2.16.1