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SubjectRe: lockdep oddity

* Ingo Molnar <mingo@elte.hu> wrote:

> > The reason is that the BUILD_LOCK_OPS macros in kernel/lockdep.c
> > don't contain any of the *_acquire calls, while all of the _unlock
> > functions contain a *_release call. Hence I get immediately
> > unbalanced locks.
>
> hmmm ... that sounds like a bug. Weird - i recently ran
> PREEMPT+SMP+LOCKDEP kernels and didnt notice this.

ok, the reason i didnt find this problem is because this is fixed in my
tree, but i didnt realize that it's a fix also for upstream ...

The patch below is what is in my tree, but that needs separation from
other changes. I'll distill a patch for upstream.

Ingo

NOT-Signed-off-by: Ingo Molnar <mingo@elte.hu>

Index: linux/kernel/spinlock.c
===================================================================
--- linux.orig/kernel/spinlock.c
+++ linux/kernel/spinlock.c
@@ -20,14 +20,14 @@
* Generic declaration of the raw read_trylock() function,
* architectures are supposed to optimize this:
*/
-int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock)
+int __lockfunc generic_raw_read_trylock(raw_rwlock_t *lock)
{
- __raw_read_lock(lock);
+ _raw_read_lock(lock);
return 1;
}
-EXPORT_SYMBOL(generic__raw_read_trylock);
+EXPORT_SYMBOL(generic_raw_read_trylock);

-int __lockfunc _spin_trylock(spinlock_t *lock)
+int __lockfunc __spin_trylock(raw_spinlock_t *lock)
{
preempt_disable();
if (_raw_spin_trylock(lock)) {
@@ -38,9 +38,46 @@ int __lockfunc _spin_trylock(spinlock_t
preempt_enable();
return 0;
}
-EXPORT_SYMBOL(_spin_trylock);
+EXPORT_SYMBOL(__spin_trylock);
+
+int __lockfunc __spin_trylock_irq(raw_spinlock_t *lock)
+{
+ local_irq_disable();
+ preempt_disable();
+
+ if (_raw_spin_trylock(lock)) {
+ spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+ return 1;
+ }
+
+ __preempt_enable_no_resched();
+ local_irq_enable();
+ preempt_check_resched();
+
+ return 0;
+}
+EXPORT_SYMBOL(__spin_trylock_irq);

-int __lockfunc _read_trylock(rwlock_t *lock)
+int __lockfunc __spin_trylock_irqsave(raw_spinlock_t *lock,
+ unsigned long *flags)
+{
+ local_irq_save(*flags);
+ preempt_disable();
+
+ if (_raw_spin_trylock(lock)) {
+ spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+ return 1;
+ }
+
+ __preempt_enable_no_resched();
+ local_irq_restore(*flags);
+ preempt_check_resched();
+
+ return 0;
+}
+EXPORT_SYMBOL(__spin_trylock_irqsave);
+
+int __lockfunc __read_trylock(raw_rwlock_t *lock)
{
preempt_disable();
if (_raw_read_trylock(lock)) {
@@ -51,9 +88,9 @@ int __lockfunc _read_trylock(rwlock_t *l
preempt_enable();
return 0;
}
-EXPORT_SYMBOL(_read_trylock);
+EXPORT_SYMBOL(__read_trylock);

-int __lockfunc _write_trylock(rwlock_t *lock)
+int __lockfunc __write_trylock(raw_rwlock_t *lock)
{
preempt_disable();
if (_raw_write_trylock(lock)) {
@@ -64,7 +101,7 @@ int __lockfunc _write_trylock(rwlock_t *
preempt_enable();
return 0;
}
-EXPORT_SYMBOL(_write_trylock);
+EXPORT_SYMBOL(__write_trylock);

/*
* If lockdep is enabled then we use the non-preemption spin-ops
@@ -72,17 +109,17 @@ EXPORT_SYMBOL(_write_trylock);
* not re-enabled during lock-acquire (which the preempt-spin-ops do):
*/
#if !defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP) || \
- defined(CONFIG_PROVE_LOCKING)
+ defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_PREEMPT_RT)

-void __lockfunc _read_lock(rwlock_t *lock)
+void __lockfunc __read_lock(raw_rwlock_t *lock)
{
preempt_disable();
rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
_raw_read_lock(lock);
}
-EXPORT_SYMBOL(_read_lock);
+EXPORT_SYMBOL(__read_lock);

-unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
+unsigned long __lockfunc __spin_lock_irqsave(raw_spinlock_t *lock)
{
unsigned long flags;

@@ -101,27 +138,27 @@ unsigned long __lockfunc _spin_lock_irqs
#endif
return flags;
}
-EXPORT_SYMBOL(_spin_lock_irqsave);
+EXPORT_SYMBOL(__spin_lock_irqsave);

-void __lockfunc _spin_lock_irq(spinlock_t *lock)
+void __lockfunc __spin_lock_irq(raw_spinlock_t *lock)
{
local_irq_disable();
preempt_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
_raw_spin_lock(lock);
}
-EXPORT_SYMBOL(_spin_lock_irq);
+EXPORT_SYMBOL(__spin_lock_irq);

-void __lockfunc _spin_lock_bh(spinlock_t *lock)
+void __lockfunc __spin_lock_bh(raw_spinlock_t *lock)
{
local_bh_disable();
preempt_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
_raw_spin_lock(lock);
}
-EXPORT_SYMBOL(_spin_lock_bh);
+EXPORT_SYMBOL(__spin_lock_bh);

-unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
+unsigned long __lockfunc __read_lock_irqsave(raw_rwlock_t *lock)
{
unsigned long flags;

@@ -131,27 +168,27 @@ unsigned long __lockfunc _read_lock_irqs
_raw_read_lock(lock);
return flags;
}
-EXPORT_SYMBOL(_read_lock_irqsave);
+EXPORT_SYMBOL(__read_lock_irqsave);

-void __lockfunc _read_lock_irq(rwlock_t *lock)
+void __lockfunc __read_lock_irq(raw_rwlock_t *lock)
{
local_irq_disable();
preempt_disable();
rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
_raw_read_lock(lock);
}
-EXPORT_SYMBOL(_read_lock_irq);
+EXPORT_SYMBOL(__read_lock_irq);

-void __lockfunc _read_lock_bh(rwlock_t *lock)
+void __lockfunc __read_lock_bh(raw_rwlock_t *lock)
{
local_bh_disable();
preempt_disable();
rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
_raw_read_lock(lock);
}
-EXPORT_SYMBOL(_read_lock_bh);
+EXPORT_SYMBOL(__read_lock_bh);

-unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
+unsigned long __lockfunc __write_lock_irqsave(raw_rwlock_t *lock)
{
unsigned long flags;

@@ -161,43 +198,43 @@ unsigned long __lockfunc _write_lock_irq
_raw_write_lock(lock);
return flags;
}
-EXPORT_SYMBOL(_write_lock_irqsave);
+EXPORT_SYMBOL(__write_lock_irqsave);

-void __lockfunc _write_lock_irq(rwlock_t *lock)
+void __lockfunc __write_lock_irq(raw_rwlock_t *lock)
{
local_irq_disable();
preempt_disable();
rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
_raw_write_lock(lock);
}
-EXPORT_SYMBOL(_write_lock_irq);
+EXPORT_SYMBOL(__write_lock_irq);

-void __lockfunc _write_lock_bh(rwlock_t *lock)
+void __lockfunc __write_lock_bh(raw_rwlock_t *lock)
{
local_bh_disable();
preempt_disable();
rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
_raw_write_lock(lock);
}
-EXPORT_SYMBOL(_write_lock_bh);
+EXPORT_SYMBOL(__write_lock_bh);

-void __lockfunc _spin_lock(spinlock_t *lock)
+void __lockfunc __spin_lock(raw_spinlock_t *lock)
{
preempt_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
_raw_spin_lock(lock);
}

-EXPORT_SYMBOL(_spin_lock);
+EXPORT_SYMBOL(__spin_lock);

-void __lockfunc _write_lock(rwlock_t *lock)
+void __lockfunc __write_lock(raw_rwlock_t *lock)
{
preempt_disable();
rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
_raw_write_lock(lock);
}

-EXPORT_SYMBOL(_write_lock);
+EXPORT_SYMBOL(__write_lock);

#else /* CONFIG_PREEMPT: */

@@ -210,7 +247,7 @@ EXPORT_SYMBOL(_write_lock);
*/

#define BUILD_LOCK_OPS(op, locktype) \
-void __lockfunc _##op##_lock(locktype##_t *lock) \
+void __lockfunc __##op##_lock(locktype##_t *lock) \
{ \
for (;;) { \
preempt_disable(); \
@@ -220,15 +257,16 @@ void __lockfunc _##op##_lock(locktype##_
\
if (!(lock)->break_lock) \
(lock)->break_lock = 1; \
- while (!op##_can_lock(lock) && (lock)->break_lock) \
+ while (!__raw_##op##_can_lock(&(lock)->raw_lock) && \
+ (lock)->break_lock) \
cpu_relax(); \
} \
(lock)->break_lock = 0; \
} \
\
-EXPORT_SYMBOL(_##op##_lock); \
+EXPORT_SYMBOL(__##op##_lock); \
\
-unsigned long __lockfunc _##op##_lock_irqsave(locktype##_t *lock) \
+unsigned long __lockfunc __##op##_lock_irqsave(locktype##_t *lock) \
{ \
unsigned long flags; \
\
@@ -242,23 +280,24 @@ unsigned long __lockfunc _##op##_lock_ir
\
if (!(lock)->break_lock) \
(lock)->break_lock = 1; \
- while (!op##_can_lock(lock) && (lock)->break_lock) \
+ while (!__raw_##op##_can_lock(&(lock)->raw_lock) && \
+ (lock)->break_lock) \
cpu_relax(); \
} \
(lock)->break_lock = 0; \
return flags; \
} \
\
-EXPORT_SYMBOL(_##op##_lock_irqsave); \
+EXPORT_SYMBOL(__##op##_lock_irqsave); \
\
-void __lockfunc _##op##_lock_irq(locktype##_t *lock) \
+void __lockfunc __##op##_lock_irq(locktype##_t *lock) \
{ \
- _##op##_lock_irqsave(lock); \
+ __##op##_lock_irqsave(lock); \
} \
\
-EXPORT_SYMBOL(_##op##_lock_irq); \
+EXPORT_SYMBOL(__##op##_lock_irq); \
\
-void __lockfunc _##op##_lock_bh(locktype##_t *lock) \
+void __lockfunc __##op##_lock_bh(locktype##_t *lock) \
{ \
unsigned long flags; \
\
@@ -267,147 +306,161 @@ void __lockfunc _##op##_lock_bh(locktype
/* irq-disabling. We use the generic preemption-aware */ \
/* function: */ \
/**/ \
- flags = _##op##_lock_irqsave(lock); \
+ flags = __##op##_lock_irqsave(lock); \
local_bh_disable(); \
local_irq_restore(flags); \
} \
\
-EXPORT_SYMBOL(_##op##_lock_bh)
+EXPORT_SYMBOL(__##op##_lock_bh)

/*
* Build preemption-friendly versions of the following
* lock-spinning functions:
*
- * _[spin|read|write]_lock()
- * _[spin|read|write]_lock_irq()
- * _[spin|read|write]_lock_irqsave()
- * _[spin|read|write]_lock_bh()
+ * __[spin|read|write]_lock()
+ * __[spin|read|write]_lock_irq()
+ * __[spin|read|write]_lock_irqsave()
+ * __[spin|read|write]_lock_bh()
*/
-BUILD_LOCK_OPS(spin, spinlock);
-BUILD_LOCK_OPS(read, rwlock);
-BUILD_LOCK_OPS(write, rwlock);
+BUILD_LOCK_OPS(spin, raw_spinlock);
+BUILD_LOCK_OPS(read, raw_rwlock);
+BUILD_LOCK_OPS(write, raw_rwlock);

#endif /* CONFIG_PREEMPT */

#ifdef CONFIG_DEBUG_LOCK_ALLOC

-void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
+void __lockfunc __spin_lock_nested(raw_spinlock_t *lock, int subclass)
{
preempt_disable();
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
_raw_spin_lock(lock);
}

-EXPORT_SYMBOL(_spin_lock_nested);
+EXPORT_SYMBOL(__spin_lock_nested);

#endif

-void __lockfunc _spin_unlock(spinlock_t *lock)
+void __lockfunc __spin_unlock(raw_spinlock_t *lock)
{
spin_release(&lock->dep_map, 1, _RET_IP_);
_raw_spin_unlock(lock);
preempt_enable();
}
-EXPORT_SYMBOL(_spin_unlock);
+EXPORT_SYMBOL(__spin_unlock);

-void __lockfunc _write_unlock(rwlock_t *lock)
+void __lockfunc __spin_unlock_no_resched(raw_spinlock_t *lock)
+{
+ spin_release(&lock->dep_map, 1, _RET_IP_);
+ _raw_spin_unlock(lock);
+ __preempt_enable_no_resched();
+}
+/* not exported */
+
+void __lockfunc __write_unlock(raw_rwlock_t *lock)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_write_unlock(lock);
preempt_enable();
}
-EXPORT_SYMBOL(_write_unlock);
+EXPORT_SYMBOL(__write_unlock);

-void __lockfunc _read_unlock(rwlock_t *lock)
+void __lockfunc __read_unlock(raw_rwlock_t *lock)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_read_unlock(lock);
preempt_enable();
}
-EXPORT_SYMBOL(_read_unlock);
+EXPORT_SYMBOL(__read_unlock);

-void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
+void __lockfunc __spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
{
spin_release(&lock->dep_map, 1, _RET_IP_);
_raw_spin_unlock(lock);
+ __preempt_enable_no_resched();
local_irq_restore(flags);
- preempt_enable();
+ preempt_check_resched();
}
-EXPORT_SYMBOL(_spin_unlock_irqrestore);
+EXPORT_SYMBOL(__spin_unlock_irqrestore);

-void __lockfunc _spin_unlock_irq(spinlock_t *lock)
+void __lockfunc __spin_unlock_irq(raw_spinlock_t *lock)
{
spin_release(&lock->dep_map, 1, _RET_IP_);
_raw_spin_unlock(lock);
+ __preempt_enable_no_resched();
local_irq_enable();
- preempt_enable();
+ preempt_check_resched();
}
-EXPORT_SYMBOL(_spin_unlock_irq);
+EXPORT_SYMBOL(__spin_unlock_irq);

-void __lockfunc _spin_unlock_bh(spinlock_t *lock)
+void __lockfunc __spin_unlock_bh(raw_spinlock_t *lock)
{
spin_release(&lock->dep_map, 1, _RET_IP_);
_raw_spin_unlock(lock);
- preempt_enable_no_resched();
+ __preempt_enable_no_resched();
local_bh_enable_ip((unsigned long)__builtin_return_address(0));
}
-EXPORT_SYMBOL(_spin_unlock_bh);
+EXPORT_SYMBOL(__spin_unlock_bh);

-void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+void __lockfunc __read_unlock_irqrestore(raw_rwlock_t *lock, unsigned long flags)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_read_unlock(lock);
+ __preempt_enable_no_resched();
local_irq_restore(flags);
- preempt_enable();
+ preempt_check_resched();
}
-EXPORT_SYMBOL(_read_unlock_irqrestore);
+EXPORT_SYMBOL(__read_unlock_irqrestore);

-void __lockfunc _read_unlock_irq(rwlock_t *lock)
+void __lockfunc __read_unlock_irq(raw_rwlock_t *lock)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_read_unlock(lock);
+ __preempt_enable_no_resched();
local_irq_enable();
- preempt_enable();
+ preempt_check_resched();
}
-EXPORT_SYMBOL(_read_unlock_irq);
+EXPORT_SYMBOL(__read_unlock_irq);

-void __lockfunc _read_unlock_bh(rwlock_t *lock)
+void __lockfunc __read_unlock_bh(raw_rwlock_t *lock)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_read_unlock(lock);
- preempt_enable_no_resched();
+ __preempt_enable_no_resched();
local_bh_enable_ip((unsigned long)__builtin_return_address(0));
}
-EXPORT_SYMBOL(_read_unlock_bh);
+EXPORT_SYMBOL(__read_unlock_bh);

-void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+void __lockfunc __write_unlock_irqrestore(raw_rwlock_t *lock, unsigned long flags)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_write_unlock(lock);
+ __preempt_enable_no_resched();
local_irq_restore(flags);
- preempt_enable();
+ preempt_check_resched();
}
-EXPORT_SYMBOL(_write_unlock_irqrestore);
+EXPORT_SYMBOL(__write_unlock_irqrestore);

-void __lockfunc _write_unlock_irq(rwlock_t *lock)
+void __lockfunc __write_unlock_irq(raw_rwlock_t *lock)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_write_unlock(lock);
+ __preempt_enable_no_resched();
local_irq_enable();
- preempt_enable();
+ preempt_check_resched();
}
-EXPORT_SYMBOL(_write_unlock_irq);
+EXPORT_SYMBOL(__write_unlock_irq);

-void __lockfunc _write_unlock_bh(rwlock_t *lock)
+void __lockfunc __write_unlock_bh(raw_rwlock_t *lock)
{
rwlock_release(&lock->dep_map, 1, _RET_IP_);
_raw_write_unlock(lock);
- preempt_enable_no_resched();
+ __preempt_enable_no_resched();
local_bh_enable_ip((unsigned long)__builtin_return_address(0));
}
-EXPORT_SYMBOL(_write_unlock_bh);
+EXPORT_SYMBOL(__write_unlock_bh);

-int __lockfunc _spin_trylock_bh(spinlock_t *lock)
+int __lockfunc __spin_trylock_bh(raw_spinlock_t *lock)
{
local_bh_disable();
preempt_disable();
@@ -416,13 +469,13 @@ int __lockfunc _spin_trylock_bh(spinlock
return 1;
}

- preempt_enable_no_resched();
+ __preempt_enable_no_resched();
local_bh_enable_ip((unsigned long)__builtin_return_address(0));
return 0;
}
-EXPORT_SYMBOL(_spin_trylock_bh);
+EXPORT_SYMBOL(__spin_trylock_bh);

-int in_lock_functions(unsigned long addr)
+int in_lock_functions(unsigned long addr)
{
/* Linker adds these: start and end of __lockfunc functions */
extern char __lock_text_start[], __lock_text_end[];
-
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