patch-2.1.79 linux/arch/ppc/lib/locks.c

• Lines: 196
• Date: Mon Jan 12 15:18:13 1998
• Orig file: v2.1.78/linux/arch/ppc/lib/locks.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.78/linux/arch/ppc/lib/locks.c linux/arch/ppc/lib/locks.c
@@ -0,0 +1,195 @@
+/*
+ * $Id: locks.c,v 1.7 1998/01/06 06:44:59 cort Exp $
+ *
+ * Locks for smp ppc 
+ * 
+ * Written by Cort Dougan (cort@cs.nmt.edu)
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+#include <asm/spinlock.h>
+
+#define DEBUG_LOCKS 1
+
+#undef INIT_STUCK
+#define INIT_STUCK 10000
+
+#undef STUCK
+#define STUCK \
+if(!--stuck) { printk("spin_lock(%p) CPU#%d nip %08lx\n", lock, cpu, nip); stuck = INIT_STUCK; }
+
+void _spin_lock(spinlock_t *lock)
+{
+	unsigned long val, nip = (unsigned long)__builtin_return_address(0);
+	int cpu = smp_processor_id();
+	int stuck = INIT_STUCK;
+	
+again:	
+	/* try expensive atomic load/store to get lock */
+	__asm__ __volatile__(
+		"10: \n\t"
+		"lwarx %0,0,%1 \n\t"
+		"stwcx. %2,0,%1 \n\t"
+		"bne- 10b \n\t"
+		: "=r" (val)
+		: "r" (&(lock->lock)), "r" ( (cpu&3)|(nip&~3L) ));
+	if(val) {
+		/* try cheap load until it's free */
+		while(lock->lock) {
+			STUCK;
+			barrier();
+		}
+		goto again;
+	}
+}
+
+void _spin_unlock(spinlock_t *lp)
+{
+	lp->lock = 0;
+}
+		
+#undef STUCK
+#define STUCK \
+if(!--stuck) { printk("_read_lock(%p) CPU#%d\n", rw, cpu); stuck = INIT_STUCK; }
+
+/*
+ * Just like x86, implement read-write locks as a 32-bit counter
+ * with the high bit (sign) being the "write" bit.
+ * -- Cort
+ */
+void _read_lock(rwlock_t *rw)
+{
+	unsigned long stuck = INIT_STUCK;
+	int cpu = smp_processor_id();
+
+again:	
+	/* get our read lock in there */
+	atomic_inc((atomic_t *) &(rw)->lock);
+	if ( (signed long)((rw)->lock) < 0) /* someone has a write lock */
+	{
+		/* turn off our read lock */
+		atomic_dec((atomic_t *) &(rw)->lock);
+		/* wait for the write lock to go away */
+		while ((signed long)((rw)->lock) < 0)
+		{
+			STUCK;
+		}
+		/* try to get the read lock again */
+		goto again;
+	}
+}
+
+void _read_unlock(rwlock_t *rw)
+{
+#ifdef DEBUG_LOCKS
+	if ( rw->lock == 0 )
+	{
+		if ( current)
+		printk("_read_unlock(): %s/%d (nip %08lX) lock %lx",
+		      current->comm,current->pid,current->tss.regs->nip,
+		      rw->lock);
+		else
+		  printk("no current\n");
+	}
+#endif /* DEBUG_LOCKS */
+	atomic_dec((atomic_t *) &(rw)->lock);
+}
+
+#undef STUCK
+#define STUCK \
+if(!--stuck) { printk("write_lock(%p) CPU#%d lock %lx)\n", rw, cpu,rw->lock); stuck = INIT_STUCK; }
+
+void _write_lock(rwlock_t *rw)
+{
+	unsigned long stuck = INIT_STUCK;
+	int cpu = smp_processor_id();
+
+again:	
+	if ( test_and_set_bit(31,&(rw)->lock) ) /* someone has a write lock */
+	{
+		while ( (rw)->lock & (1<<31) ) /* wait for write lock */
+		{
+			STUCK;
+		}
+		goto again;
+	}
+	
+	if ( (rw)->lock & ~(1<<31)) /* someone has a read lock */
+	{
+		/* clear our write lock and wait for reads to go away */
+		clear_bit(31,&(rw)->lock);
+		while ( (rw)->lock & ~(1<<31) )
+		{
+			STUCK;
+		}
+		goto again;
+	}
+}
+
+void _write_unlock(rwlock_t *rw)
+{
+#ifdef DEBUG_LOCKS
+	if ( !(rw->lock & (1<<31)) )
+	{
+		if ( current)
+		printk("_write_lock(): %s/%d (nip %08lX) lock %lx",
+		      current->comm,current->pid,current->tss.regs->nip,
+		      rw->lock);
+		else
+		  printk("no current\n");
+	}
+#endif /* DEBUG_LOCKS */
+	clear_bit(31,&(rw)->lock);
+}
+
+void __lock_kernel(struct task_struct *task)
+{
+#ifdef DEBUG_LOCKS
+	if ( (signed long)(task->lock_depth) < 0 )
+	{
+		printk("__lock_kernel(): %s/%d (nip %08lX) lock depth %x\n",
+		      task->comm,task->pid,task->tss.regs->nip,
+		      task->lock_depth);
+	}
+#endif /* DEBUG_LOCKS */
+	/* mine! */
+	if ( atomic_inc_return((atomic_t *) &task->lock_depth) == 1 )
+		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 )
+	{
+		printk("__unlock_kernel(): %s/%d (nip %08lX) lock depth %x\n",
+		      task->comm,task->pid,task->tss.regs->nip,
+		      task->lock_depth);
+		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) )
+	{
+		klock_info.akp = NO_PROC_ID;		
+		klock_info.kernel_flag = 0;
+	}
+}	
+
+void reacquire_kernel_lock(struct task_struct *task, int cpu,int depth)
+{
+	if (depth)
+	{
+		__cli();
+		__lock_kernel(task);
+		task->lock_depth = depth;
+		__sti();
+       }
+}
+