[PATCH] lockdep: prove spinlock rwlock locking correctness

Use the lock validator framework to prove spinlock and rwlock locking
correctness.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 81 insertions, 9 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index df6ef32636..47dbcd570c 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
 obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
 obj-$(CONFIG_SMP) += cpu.o spinlock.o
 obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
+obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
 obj-$(CONFIG_UID16) += uid16.o
 obj-$(CONFIG_MODULES) += module.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
diff --git a/kernel/sched.c b/kernel/sched.c
index 9118299665..ae4db0185b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -308,6 +308,13 @@ static inline void finish_lock_switch(runqueue_t *rq, task_t *prev)
         /* this is a valid case when another task releases the spinlock */
         rq->lock.owner = current;
 #endif
+        /*
+         * If we are tracking spinlock dependencies then we have to
+         * fix up the runqueue lock - which gets 'carried over' from
+         * prev into current:
+         */
+        spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
+
         spin_unlock_irq(&rq->lock);
 }
 
@@ -1778,6 +1785,7 @@ task_t * context_switch(runqueue_t *rq, task_t *prev, task_t *next)
                 WARN_ON(rq->prev_mm);
                 rq->prev_mm = oldmm;
         }
+        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
 
         /* Here we just switch the register state and the stack. */
         switch_to(prev, next, prev);
@@ -4384,6 +4392,7 @@ asmlinkage long sys_sched_yield(void)
          * no need to preempt or enable interrupts:
          */
         __release(rq->lock);
+        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
         _raw_spin_unlock(&rq->lock);
         preempt_enable_no_resched();
 
@@ -4447,6 +4456,7 @@ int cond_resched_lock(spinlock_t *lock)
                 spin_lock(lock);
         }
         if (need_resched() && __resched_legal()) {
+                spin_release(&lock->dep_map, 1, _THIS_IP_);
                 _raw_spin_unlock(lock);
                 preempt_enable_no_resched();
                 __cond_resched();
diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index b31e54eadf..bfd6ad9c03 100644
--- a/kernel/spinlock.c
+++ b/kernel/spinlock.c
@@ -13,6 +13,7 @@
 #include <linux/preempt.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
+#include <linux/debug_locks.h>
 #include <linux/module.h>
 
 /*
@@ -29,8 +30,10 @@ EXPORT_SYMBOL(generic__raw_read_trylock);
 int __lockfunc _spin_trylock(spinlock_t *lock)
 {
         preempt_disable();
-        if (_raw_spin_trylock(lock))
+        if (_raw_spin_trylock(lock)) {
+                spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
                 return 1;
+        }
         
         preempt_enable();
         return 0;
@@ -40,8 +43,10 @@ EXPORT_SYMBOL(_spin_trylock);
 int __lockfunc _read_trylock(rwlock_t *lock)
 {
         preempt_disable();
-        if (_raw_read_trylock(lock))
+        if (_raw_read_trylock(lock)) {
+                rwlock_acquire_read(&lock->dep_map, 0, 1, _RET_IP_);
                 return 1;
+        }
 
         preempt_enable();
         return 0;
@@ -51,19 +56,28 @@ EXPORT_SYMBOL(_read_trylock);
 int __lockfunc _write_trylock(rwlock_t *lock)
 {
         preempt_disable();
-        if (_raw_write_trylock(lock))
+        if (_raw_write_trylock(lock)) {
+                rwlock_acquire(&lock->dep_map, 0, 1, _RET_IP_);
                 return 1;
+        }
 
         preempt_enable();
         return 0;
 }
 EXPORT_SYMBOL(_write_trylock);
 
-#if !defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP)
+/*
+ * If lockdep is enabled then we use the non-preemption spin-ops
+ * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
+ * not re-enabled during lock-acquire (which the preempt-spin-ops do):
+ */
+#if !defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP) || \
+        defined(CONFIG_PROVE_LOCKING)
 
 void __lockfunc _read_lock(rwlock_t *lock)
 {
         preempt_disable();
+        rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
         _raw_read_lock(lock);
 }
 EXPORT_SYMBOL(_read_lock);
@@ -74,7 +88,17 @@ unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
 
         local_irq_save(flags);
         preempt_disable();
+        spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+        /*
+         * On lockdep we dont want the hand-coded irq-enable of
+         * _raw_spin_lock_flags() code, because lockdep assumes
+         * that interrupts are not re-enabled during lock-acquire:
+         */
+#ifdef CONFIG_PROVE_LOCKING
+        _raw_spin_lock(lock);
+#else
         _raw_spin_lock_flags(lock, &flags);
+#endif
         return flags;
 }
 EXPORT_SYMBOL(_spin_lock_irqsave);
@@ -83,6 +107,7 @@ void __lockfunc _spin_lock_irq(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);
@@ -91,6 +116,7 @@ void __lockfunc _spin_lock_bh(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);
@@ -101,6 +127,7 @@ unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
 
         local_irq_save(flags);
         preempt_disable();
+        rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
         _raw_read_lock(lock);
         return flags;
 }
@@ -110,6 +137,7 @@ void __lockfunc _read_lock_irq(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);
@@ -118,6 +146,7 @@ void __lockfunc _read_lock_bh(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);
@@ -128,6 +157,7 @@ unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
 
         local_irq_save(flags);
         preempt_disable();
+        rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
         _raw_write_lock(lock);
         return flags;