[PATCH] lockdep: clean up rwsems

Clean up rwsems.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-i386/rwsem.h

@@ -61,23 +61,11 @@ struct rw_semaphore {
 #define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
 	spinlock_t		wait_lock;
 	struct list_head	wait_list;
-#if RWSEM_DEBUG
-	int			debug;
-#endif
 };
 
-/*
- * initialisation
- */
-#if RWSEM_DEBUG
-#define __RWSEM_DEBUG_INIT      , 0
-#else
-#define __RWSEM_DEBUG_INIT	/* */
-#endif
-
 #define __RWSEM_INITIALIZER(name) \
 { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) \
-	__RWSEM_DEBUG_INIT }
+	}
 
 #define DECLARE_RWSEM(name) \
 	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
@@ -87,9 +75,6 @@ static inline void init_rwsem(struct rw_semaphore *sem)
 	sem->count = RWSEM_UNLOCKED_VALUE;
 	spin_lock_init(&sem->wait_lock);
 	INIT_LIST_HEAD(&sem->wait_list);
-#if RWSEM_DEBUG
-	sem->debug = 0;
-#endif
 }
 
 /*

include/linux/rwsem-spinlock.h

@@ -32,22 +32,10 @@ struct rw_semaphore {
 	__s32			activity;
 	spinlock_t		wait_lock;
 	struct list_head	wait_list;
-#if RWSEM_DEBUG
-	int			debug;
-#endif
 };
 
-/*
- * initialisation
- */
-#if RWSEM_DEBUG
-#define __RWSEM_DEBUG_INIT      , 0
-#else
-#define __RWSEM_DEBUG_INIT	/* */
-#endif
-
 #define __RWSEM_INITIALIZER(name) \
-{ 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT }
+{ 0, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) }
 
 #define DECLARE_RWSEM(name) \
 	struct rw_semaphore name = __RWSEM_INITIALIZER(name)

include/linux/rwsem.h

@@ -9,8 +9,6 @@
 
 #include <linux/linkage.h>
 
-#define RWSEM_DEBUG 0
-
 #ifdef __KERNEL__
 
 #include <linux/types.h>
@@ -26,23 +24,13 @@ struct rw_semaphore;
 #include <asm/rwsem.h> /* use an arch-specific implementation */
 #endif
 
-#ifndef rwsemtrace
-#if RWSEM_DEBUG
-extern void FASTCALL(rwsemtrace(struct rw_semaphore *sem, const char *str));
-#else
-#define rwsemtrace(SEM,FMT)
-#endif
-#endif
-
 /*
  * lock for reading
  */
 static inline void down_read(struct rw_semaphore *sem)
 {
 	might_sleep();
-	rwsemtrace(sem,"Entering down_read");
 	__down_read(sem);
-	rwsemtrace(sem,"Leaving down_read");
 }
 
 /*
@@ -51,9 +39,7 @@ static inline void down_read(struct rw_semaphore *sem)
 static inline int down_read_trylock(struct rw_semaphore *sem)
 {
 	int ret;
-	rwsemtrace(sem,"Entering down_read_trylock");
 	ret = __down_read_trylock(sem);
-	rwsemtrace(sem,"Leaving down_read_trylock");
 	return ret;
 }
 
@@ -63,9 +49,7 @@ static inline int down_read_trylock(struct rw_semaphore *sem)
 static inline void down_write(struct rw_semaphore *sem)
 {
 	might_sleep();
-	rwsemtrace(sem,"Entering down_write");
 	__down_write(sem);
-	rwsemtrace(sem,"Leaving down_write");
 }
 
 /*
@@ -74,9 +58,7 @@ static inline void down_write(struct rw_semaphore *sem)
 static inline int down_write_trylock(struct rw_semaphore *sem)
 {
 	int ret;
-	rwsemtrace(sem,"Entering down_write_trylock");
 	ret = __down_write_trylock(sem);
-	rwsemtrace(sem,"Leaving down_write_trylock");
 	return ret;
 }
 
@@ -85,9 +67,7 @@ static inline int down_write_trylock(struct rw_semaphore *sem)
  */
 static inline void up_read(struct rw_semaphore *sem)
 {
-	rwsemtrace(sem,"Entering up_read");
 	__up_read(sem);
-	rwsemtrace(sem,"Leaving up_read");
 }
 
 /*
@@ -95,9 +75,7 @@ static inline void up_read(struct rw_semaphore *sem)
  */
 static inline void up_write(struct rw_semaphore *sem)
 {
-	rwsemtrace(sem,"Entering up_write");
 	__up_write(sem);
-	rwsemtrace(sem,"Leaving up_write");
 }
 
 /*
@@ -105,9 +83,7 @@ static inline void up_write(struct rw_semaphore *sem)
  */
 static inline void downgrade_write(struct rw_semaphore *sem)
 {
-	rwsemtrace(sem,"Entering downgrade_write");
 	__downgrade_write(sem);
-	rwsemtrace(sem,"Leaving downgrade_write");
 }
 
 #endif /* __KERNEL__ */

kernel/rwsem.c

@@ -0,0 +1,105 @@
+/* kernel/rwsem.c: R/W semaphores, public implementation
+ *
+ * Written by David Howells (dhowells@redhat.com).
+ * Derived from asm-i386/semaphore.h
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rwsem.h>
+
+#include <asm/system.h>
+#include <asm/atomic.h>
+
+/*
+ * lock for reading
+ */
+void down_read(struct rw_semaphore *sem)
+{
+	might_sleep();
+	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
+
+	__down_read(sem);
+}
+
+EXPORT_SYMBOL(down_read);
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+int down_read_trylock(struct rw_semaphore *sem)
+{
+	int ret = __down_read_trylock(sem);
+
+	if (ret == 1)
+		rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
+	return ret;
+}
+
+EXPORT_SYMBOL(down_read_trylock);
+
+/*
+ * lock for writing
+ */
+void down_write(struct rw_semaphore *sem)
+{
+	might_sleep();
+	rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+
+	__down_write(sem);
+}
+
+EXPORT_SYMBOL(down_write);
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+int down_write_trylock(struct rw_semaphore *sem)
+{
+	int ret = __down_write_trylock(sem);
+
+	if (ret == 1)
+		rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+	return ret;
+}
+
+EXPORT_SYMBOL(down_write_trylock);
+
+/*
+ * release a read lock
+ */
+void up_read(struct rw_semaphore *sem)
+{
+	rwsem_release(&sem->dep_map, 1, _RET_IP_);
+
+	__up_read(sem);
+}
+
+EXPORT_SYMBOL(up_read);
+
+/*
+ * release a write lock
+ */
+void up_write(struct rw_semaphore *sem)
+{
+	rwsem_release(&sem->dep_map, 1, _RET_IP_);
+
+	__up_write(sem);
+}
+
+EXPORT_SYMBOL(up_write);
+
+/*
+ * downgrade write lock to read lock
+ */
+void downgrade_write(struct rw_semaphore *sem)
+{
+	/*
+	 * lockdep: a downgraded write will live on as a write
+	 * dependency.
+	 */
+	__downgrade_write(sem);
+}
+
+EXPORT_SYMBOL(downgrade_write);

lib/rwsem-spinlock.c

@@ -17,16 +17,6 @@ struct rwsem_waiter {
 #define RWSEM_WAITING_FOR_WRITE	0x00000002
 };
 
-#if RWSEM_DEBUG
-void rwsemtrace(struct rw_semaphore *sem, const char *str)
-{
-	if (sem->debug)
-		printk("[%d] %s({%d,%d})\n",
-		       current->pid, str, sem->activity,
-		       list_empty(&sem->wait_list) ? 0 : 1);
-}
-#endif
-
 /*
  * initialise the semaphore
  */
@@ -35,9 +25,6 @@ void fastcall init_rwsem(struct rw_semaphore *sem)
 	sem->activity = 0;
 	spin_lock_init(&sem->wait_lock);
 	INIT_LIST_HEAD(&sem->wait_list);
-#if RWSEM_DEBUG
-	sem->debug = 0;
-#endif
 }
 
 /*
@@ -56,8 +43,6 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
 	struct task_struct *tsk;
 	int woken;
 
-	rwsemtrace(sem, "Entering __rwsem_do_wake");
-
 	waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
 
 	if (!wakewrite) {
@@ -104,7 +89,6 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
 	sem->activity += woken;
 
  out:
-	rwsemtrace(sem, "Leaving __rwsem_do_wake");
 	return sem;
 }
 
@@ -138,8 +122,6 @@ void fastcall __sched __down_read(struct rw_semaphore *sem)
 	struct rwsem_waiter waiter;
 	struct task_struct *tsk;
 
-	rwsemtrace(sem, "Entering __down_read");
-
 	spin_lock_irq(&sem->wait_lock);
 
 	if (sem->activity >= 0 && list_empty(&sem->wait_list)) {
@@ -171,9 +153,8 @@ void fastcall __sched __down_read(struct rw_semaphore *sem)
 	}
 
 	tsk->state = TASK_RUNNING;
-
  out:
-	rwsemtrace(sem, "Leaving __down_read");
+	;
 }
 
 /*
@@ -184,7 +165,6 @@ int fastcall __down_read_trylock(struct rw_semaphore *sem)
 	unsigned long flags;
 	int ret = 0;
 
-	rwsemtrace(sem, "Entering __down_read_trylock");
 
 	spin_lock_irqsave(&sem->wait_lock, flags);
 
@@ -196,7 +176,6 @@ int fastcall __down_read_trylock(struct rw_semaphore *sem)
 
 	spin_unlock_irqrestore(&sem->wait_lock, flags);
 
-	rwsemtrace(sem, "Leaving __down_read_trylock");
 	return ret;
 }
 
@@ -209,8 +188,6 @@ void fastcall __sched __down_write(struct rw_semaphore *sem)
 	struct rwsem_waiter waiter;
 	struct task_struct *tsk;
 
-	rwsemtrace(sem, "Entering __down_write");
-
 	spin_lock_irq(&sem->wait_lock);
 
 	if (sem->activity == 0 && list_empty(&sem->wait_list)) {
@@ -242,9 +219,8 @@ void fastcall __sched __down_write(struct rw_semaphore *sem)
 	}
 
 	tsk->state = TASK_RUNNING;
-
  out:
-	rwsemtrace(sem, "Leaving __down_write");
+	;
 }
 
 /*
@@ -255,8 +231,6 @@ int fastcall __down_write_trylock(struct rw_semaphore *sem)
 	unsigned long flags;
 	int ret = 0;
 
-	rwsemtrace(sem, "Entering __down_write_trylock");
-
 	spin_lock_irqsave(&sem->wait_lock, flags);
 
 	if (sem->activity == 0 && list_empty(&sem->wait_list)) {
@@ -267,7 +241,6 @@ int fastcall __down_write_trylock(struct rw_semaphore *sem)
 
 	spin_unlock_irqrestore(&sem->wait_lock, flags);
 
-	rwsemtrace(sem, "Leaving __down_write_trylock");
 	return ret;
 }
 
@@ -278,16 +251,12 @@ void fastcall __up_read(struct rw_semaphore *sem)
 {
 	unsigned long flags;
 
-	rwsemtrace(sem, "Entering __up_read");
-
 	spin_lock_irqsave(&sem->wait_lock, flags);
 
 	if (--sem->activity == 0 && !list_empty(&sem->wait_list))
 		sem = __rwsem_wake_one_writer(sem);
 
 	spin_unlock_irqrestore(&sem->wait_lock, flags);
-
-	rwsemtrace(sem, "Leaving __up_read");
 }
 
 /*
@@ -297,8 +266,6 @@ void fastcall __up_write(struct rw_semaphore *sem)
 {
 	unsigned long flags;
 
-	rwsemtrace(sem, "Entering __up_write");
-
 	spin_lock_irqsave(&sem->wait_lock, flags);
 
 	sem->activity = 0;
@@ -306,8 +273,6 @@ void fastcall __up_write(struct rw_semaphore *sem)
 		sem = __rwsem_do_wake(sem, 1);
 
 	spin_unlock_irqrestore(&sem->wait_lock, flags);
-
-	rwsemtrace(sem, "Leaving __up_write");
 }
 
 /*
@@ -318,8 +283,6 @@ void fastcall __downgrade_write(struct rw_semaphore *sem)
 {
 	unsigned long flags;
 
-	rwsemtrace(sem, "Entering __downgrade_write");
-
 	spin_lock_irqsave(&sem->wait_lock, flags);
 
 	sem->activity = 1;
@@ -327,8 +290,6 @@ void fastcall __downgrade_write(struct rw_semaphore *sem)
 		sem = __rwsem_do_wake(sem, 0);
 
 	spin_unlock_irqrestore(&sem->wait_lock, flags);
-
-	rwsemtrace(sem, "Leaving __downgrade_write");
 }
 
 EXPORT_SYMBOL(init_rwsem);
@@ -339,6 +300,3 @@ EXPORT_SYMBOL(__down_write_trylock);
 EXPORT_SYMBOL(__up_read);
 EXPORT_SYMBOL(__up_write);
 EXPORT_SYMBOL(__downgrade_write);
-#if RWSEM_DEBUG
-EXPORT_SYMBOL(rwsemtrace);
-#endif

lib/rwsem.c

@@ -16,17 +16,6 @@ struct rwsem_waiter {
 #define RWSEM_WAITING_FOR_WRITE	0x00000002
 };
 
-#if RWSEM_DEBUG
-#undef rwsemtrace
-void rwsemtrace(struct rw_semaphore *sem, const char *str)
-{
-	printk("sem=%p\n", sem);
-	printk("(sem)=%08lx\n", sem->count);
-	if (sem->debug)
-		printk("[%d] %s({%08lx})\n", current->pid, str, sem->count);
-}
-#endif
-
 /*
  * handle the lock release when processes blocked on it that can now run
  * - if we come here from up_xxxx(), then:
@@ -45,8 +34,6 @@ __rwsem_do_wake(struct rw_semaphore *sem, int downgrading)
 	struct list_head *next;
 	signed long oldcount, woken, loop;
 
-	rwsemtrace(sem, "Entering __rwsem_do_wake");
-
 	if (downgrading)
 		goto dont_wake_writers;
 
@@ -127,7 +114,6 @@ __rwsem_do_wake(struct rw_semaphore *sem, int downgrading)
 	next->prev = &sem->wait_list;
 
  out:
-	rwsemtrace(sem, "Leaving __rwsem_do_wake");
 	return sem;
 
 	/* undo the change to count, but check for a transition 1->0 */
@@ -186,13 +172,9 @@ rwsem_down_read_failed(struct rw_semaphore *sem)
 {
 	struct rwsem_waiter waiter;
 
-	rwsemtrace(sem, "Entering rwsem_down_read_failed");
-
 	waiter.flags = RWSEM_WAITING_FOR_READ;
 	rwsem_down_failed_common(sem, &waiter,
 				RWSEM_WAITING_BIAS - RWSEM_ACTIVE_BIAS);
-
-	rwsemtrace(sem, "Leaving rwsem_down_read_failed");
 	return sem;
 }
 
@@ -204,12 +186,9 @@ rwsem_down_write_failed(struct rw_semaphore *sem)
 {
 	struct rwsem_waiter waiter;
 
-	rwsemtrace(sem, "Entering rwsem_down_write_failed");
-
 	waiter.flags = RWSEM_WAITING_FOR_WRITE;
 	rwsem_down_failed_common(sem, &waiter, -RWSEM_ACTIVE_BIAS);
 
-	rwsemtrace(sem, "Leaving rwsem_down_write_failed");
 	return sem;
 }
 
@@ -221,8 +200,6 @@ struct rw_semaphore fastcall *rwsem_wake(struct rw_semaphore *sem)
 {
 	unsigned long flags;
 
-	rwsemtrace(sem, "Entering rwsem_wake");
-
 	spin_lock_irqsave(&sem->wait_lock, flags);
 
 	/* do nothing if list empty */
@@ -231,8 +208,6 @@ struct rw_semaphore fastcall *rwsem_wake(struct rw_semaphore *sem)
 
 	spin_unlock_irqrestore(&sem->wait_lock, flags);
 
-	rwsemtrace(sem, "Leaving rwsem_wake");
-
 	return sem;
 }
 
@@ -245,8 +220,6 @@ struct rw_semaphore fastcall *rwsem_downgrade_wake(struct rw_semaphore *sem)
 {
 	unsigned long flags;
 
-	rwsemtrace(sem, "Entering rwsem_downgrade_wake");
-
 	spin_lock_irqsave(&sem->wait_lock, flags);
 
 	/* do nothing if list empty */
@@ -255,7 +228,6 @@ struct rw_semaphore fastcall *rwsem_downgrade_wake(struct rw_semaphore *sem)
 
 	spin_unlock_irqrestore(&sem->wait_lock, flags);
 
-	rwsemtrace(sem, "Leaving rwsem_downgrade_wake");
 	return sem;
 }
 
@@ -263,6 +235,3 @@ EXPORT_SYMBOL(rwsem_down_read_failed);
 EXPORT_SYMBOL(rwsem_down_write_failed);
 EXPORT_SYMBOL(rwsem_wake);
 EXPORT_SYMBOL(rwsem_downgrade_wake);
-#if RWSEM_DEBUG
-EXPORT_SYMBOL(rwsemtrace);
-#endif