patch-2.4.10 linux/arch/ppc/lib/locks.c

• Lines: 265
• Date: Tue Aug 28 06:58:33 2001
• Orig file: v2.4.9/linux/arch/ppc/lib/locks.c
• Orig date: Mon May 21 17:04:47 2001

diff -u --recursive --new-file v2.4.9/linux/arch/ppc/lib/locks.c linux/arch/ppc/lib/locks.c
@@ -1,5 +1,5 @@
 /*
- * BK Id: SCCS/s.locks.c 1.8 05/17/01 18:14:22 cort
+ * BK Id: SCCS/s.locks.c 1.11 08/19/01 22:27:32 paulus
  */
 /*
  * Locks for smp ppc 
@@ -16,29 +16,53 @@
 #include <asm/system.h>
 #include <asm/io.h>
 
-#define DEBUG_LOCKS 1
+#ifdef SPINLOCK_DEBUG
 
 #undef INIT_STUCK
 #define INIT_STUCK 200000000 /*0xffffffff*/
 
+/*
+ * Try to acquire a spinlock.
+ * Only does the stwcx. if the load returned 0 - the Programming
+ * Environments Manual suggests not doing unnecessary stcwx.'s
+ * since they may inhibit forward progress by other CPUs in getting
+ * a lock.
+ */
+static unsigned long __spin_trylock(volatile unsigned long *lock)
+{
+	unsigned long ret;
+
+	__asm__ __volatile__ ("\n\
+1:	lwarx	%0,0,%1\n\
+	cmpwi	0,%0,0\n\
+	bne	2f\n\
+	stwcx.	%2,0,%1\n\
+	bne-	1b\n\
+	isync\n\
+2:"
+	: "=&r"(ret)
+	: "r"(lock), "r"(1)
+	: "cr0", "memory");
+
+	return ret;
+}
+
 void _spin_lock(spinlock_t *lock)
 {
 	int cpu = smp_processor_id();
-#ifdef DEBUG_LOCKS
 	unsigned int stuck = INIT_STUCK;
-#endif /* DEBUG_LOCKS */
 	while (__spin_trylock(&lock->lock)) {
-#ifdef DEBUG_LOCKS
-		if(!--stuck) {
-			printk("_spin_lock(%p) CPU#%d NIP %p"
-			       " holder: cpu %ld pc %08lX\n",
-			       lock, cpu, __builtin_return_address(0),
-			       lock->owner_cpu,lock->owner_pc);
-			stuck = INIT_STUCK;
-			/* steal the lock */
-			/*xchg_u32((void *)&lock->lock,0);*/
+		while ((unsigned volatile long)lock->lock != 0) {
+			if (!--stuck) {
+				printk("_spin_lock(%p) CPU#%d NIP %p"
+				       " holder: cpu %ld pc %08lX\n",
+				       lock, cpu, __builtin_return_address(0),
+				       lock->owner_cpu,lock->owner_pc);
+				stuck = INIT_STUCK;
+				/* steal the lock */
+				/*xchg_u32((void *)&lock->lock,0);*/
+			}
 		}
-#endif /* DEBUG_LOCKS */
 	}
 	lock->owner_pc = (unsigned long)__builtin_return_address(0);
 	lock->owner_cpu = cpu;
@@ -53,11 +77,8 @@
 	return 1;
 }
 
-
-
 void _spin_unlock(spinlock_t *lp)
 {
-#ifdef DEBUG_LOCKS
   	if ( !lp->lock )
 		printk("_spin_unlock(%p): no lock cpu %d curr PC %p %s/%d\n",
 		       lp, smp_processor_id(), __builtin_return_address(0),
@@ -66,13 +87,12 @@
 		printk("_spin_unlock(%p): cpu %d trying clear of cpu %d pc %lx val %lx\n",
 		      lp, smp_processor_id(), (int)lp->owner_cpu,
 		      lp->owner_pc,lp->lock);
-#endif /* DEBUG_LOCKS */
 	lp->owner_pc = lp->owner_cpu = 0;
 	wmb();
 	lp->lock = 0;
-	wmb();
 }
 
+
 /*
  * Just like x86, implement read-write locks as a 32-bit counter
  * with the high bit (sign) being the "write" bit.
@@ -80,14 +100,11 @@
  */
 void _read_lock(rwlock_t *rw)
 {
-#ifdef DEBUG_LOCKS
 	unsigned long stuck = INIT_STUCK;
 	int cpu = smp_processor_id();
-#endif /* DEBUG_LOCKS */		  
 
 again:	
 	/* get our read lock in there */
-	wmb();
 	atomic_inc((atomic_t *) &(rw)->lock);
 	if ( (signed long)((rw)->lock) < 0) /* someone has a write lock */
 	{
@@ -96,13 +113,11 @@
 		/* wait for the write lock to go away */
 		while ((signed long)((rw)->lock) < 0)
 		{
-#ifdef DEBUG_LOCKS
 			if(!--stuck)
 			{
 				printk("_read_lock(%p) CPU#%d\n", rw, cpu);
 				stuck = INIT_STUCK;
 			}
-#endif /* DEBUG_LOCKS */
 		}
 		/* try to get the read lock again */
 		goto again;
@@ -112,38 +127,30 @@
 
 void _read_unlock(rwlock_t *rw)
 {
-#ifdef DEBUG_LOCKS
 	if ( rw->lock == 0 )
 		printk("_read_unlock(): %s/%d (nip %08lX) lock %lx\n",
 		       current->comm,current->pid,current->thread.regs->nip,
 		      rw->lock);
-#endif /* DEBUG_LOCKS */
 	wmb();
 	atomic_dec((atomic_t *) &(rw)->lock);
-	wmb();
 }
 
 void _write_lock(rwlock_t *rw)
 {
-#ifdef DEBUG_LOCKS
 	unsigned long stuck = INIT_STUCK;
 	int cpu = smp_processor_id();
-#endif /* DEBUG_LOCKS */		  
 
 again:
-	wmb();
 	if ( test_and_set_bit(31,&(rw)->lock) ) /* someone has a write lock */
 	{
 		while ( (rw)->lock & (1<<31) ) /* wait for write lock */
 		{
-#ifdef DEBUG_LOCKS
 			if(!--stuck)
 			{
 				printk("write_lock(%p) CPU#%d lock %lx)\n",
 				       rw, cpu,rw->lock);
 				stuck = INIT_STUCK;
 			}
-#endif /* DEBUG_LOCKS */		  
 			barrier();
 		}
 		goto again;
@@ -155,14 +162,12 @@
 		clear_bit(31,&(rw)->lock);
 		while ( (rw)->lock & ~(1<<31) )
 		{
-#ifdef DEBUG_LOCKS
 			if(!--stuck)
 			{
 				printk("write_lock(%p) 2 CPU#%d lock %lx)\n",
 				       rw, cpu,rw->lock);
 				stuck = INIT_STUCK;
 			}
-#endif /* DEBUG_LOCKS */
 			barrier();
 		}
 		goto again;
@@ -172,79 +177,12 @@
 
 void _write_unlock(rwlock_t *rw)
 {
-#ifdef DEBUG_LOCKS
 	if ( !(rw->lock & (1<<31)) )
 		printk("_write_lock(): %s/%d (nip %08lX) lock %lx\n",
 		      current->comm,current->pid,current->thread.regs->nip,
 		      rw->lock);
-#endif /* DEBUG_LOCKS */
 	wmb();
 	clear_bit(31,&(rw)->lock);
-	wmb();
-}
-
-void __lock_kernel(struct task_struct *task)
-{
-#ifdef DEBUG_LOCKS
-	unsigned long stuck = INIT_STUCK;
-	
-	if ( (signed long)(task->lock_depth) < 0 )
-	{
-		printk("__lock_kernel(): %s/%d (nip %08lX) lock depth %x\n",
-		      task->comm,task->pid,task->thread.regs->nip,
-		      task->lock_depth);
-	}
-#endif /* DEBUG_LOCKS */
-
-	if (atomic_inc_return((atomic_t *) &task->lock_depth) != 1)
-		return;
-	/* mine! */
-	while (__spin_trylock(&klock_info.kernel_flag)) {
-#ifdef DEBUG_LOCKS
-		if(!--stuck) {
-			printk("_lock_kernel() CPU#%d NIP %p\n",
-			       smp_processor_id(),
-			       __builtin_return_address(0));
-			stuck = INIT_STUCK;
-		}
-#endif /* DEBUG_LOCKS */
-	}
-	
-	klock_info.akp = smp_processor_id();
-	/* my kernel mode! mine!!! */
 }
 
-void __unlock_kernel(struct task_struct *task)
-{
-#ifdef DEBUG_LOCKS
- 	if ((task->lock_depth == 0) || (klock_info.kernel_flag != KLOCK_HELD))
-	{
-		printk("__unlock_kernel(): %s/%d (nip %08lX) "
-		       "lock depth %x flags %lx\n",
-		       task->comm,task->pid,task->thread.regs->nip,
-		       task->lock_depth, klock_info.kernel_flag);
-		klock_info.akp = NO_PROC_ID;		
-		klock_info.kernel_flag = 0;
-		return;
-	}
-#endif /* DEBUG_LOCKS */
-	if (atomic_dec_and_test((atomic_t *) &task->lock_depth))
-	{
-		wmb();
-		klock_info.akp = NO_PROC_ID;
-		wmb();
-		klock_info.kernel_flag = KLOCK_CLEAR;
-		wmb();
-	}
-}	
-
-void reacquire_kernel_lock(struct task_struct *task, int cpu,int depth)
-{
-	if (depth)
-	{
-		__cli();
-		__lock_kernel(task);
-		task->lock_depth = depth;
-		__sti();
-	}
-}
+#endif