patch-2.1.127 linux/arch/sparc64/lib/debuglocks.c

• Lines: 279
• Date: Tue Oct 27 09:52:20 1998
• Orig file: v2.1.126/linux/arch/sparc64/lib/debuglocks.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.126/linux/arch/sparc64/lib/debuglocks.c linux/arch/sparc64/lib/debuglocks.c
@@ -0,0 +1,278 @@
+/* $Id: debuglocks.c,v 1.2 1998/10/13 09:07:27 davem Exp $
+ * debuglocks.c: Debugging versions of SMP locking primitives.
+ *
+ * Copyright (C) 1998 David S. Miller (davem@dm.cobaltmicro.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <asm/system.h>
+#include <asm/spinlock.h>
+
+#ifdef __SMP__
+
+/* To enable this code, just define SPIN_LOCK_DEBUG in asm/spinlock.h */
+#ifdef SPIN_LOCK_DEBUG
+
+#define GET_CALLER(PC) __asm__ __volatile__("mov %%i7, %0" : "=r" (PC))
+
+static inline void show (char *str, spinlock_t *lock, unsigned long caller)
+{
+	int cpu = smp_processor_id();
+
+	printk("%s(%p) CPU#%d stuck at %08x, owner PC(%08x):CPU(%x)\n",
+	       str, lock, cpu, (unsigned int) caller,
+	       lock->owner_pc, lock->owner_cpu);
+}
+
+static inline void show_read (char *str, rwlock_t *lock, unsigned long caller)
+{
+	int cpu = smp_processor_id();
+
+	printk("%s(%p) CPU#%d stuck at %08x, writer PC(%08x):CPU(%x)\n",
+	       str, lock, cpu, (unsigned int) caller,
+	       lock->writer_pc, lock->writer_cpu);
+}
+
+static inline void show_write (char *str, rwlock_t *lock, unsigned long caller)
+{
+	int cpu = smp_processor_id();
+
+	printk("%s(%p) CPU#%d stuck at %08x\n",
+	       str, lock, cpu, (unsigned int) caller);
+	printk("Writer: PC(%08x):CPU(%x)\n",
+	       lock->writer_pc, lock->writer_cpu);
+	printk("Readers: 0[%08x] 1[%08x] 2[%08x] 4[%08x]\n",
+	       lock->reader_pc[0], lock->reader_pc[1],
+	       lock->reader_pc[2], lock->reader_pc[3]);
+}
+
+#undef INIT_STUCK
+#define INIT_STUCK 100000000
+
+void _do_spin_lock(spinlock_t *lock, char *str)
+{
+	unsigned long caller, val;
+	int stuck = INIT_STUCK;
+	int cpu = smp_processor_id();
+
+	GET_CALLER(caller);
+again:
+	__asm__ __volatile__("ldstub [%1], %0"
+			     : "=r" (val)
+			     : "r" (&(lock->lock))
+			     : "memory");
+	membar("#StoreLoad | #StoreStore");
+	if (val) {
+		while (lock->lock) {
+			if (!--stuck) {
+				show(str, lock, caller);
+				stuck = INIT_STUCK;
+			}
+			membar("#LoadLoad");
+		}
+		goto again;
+	}
+	lock->owner_pc = ((unsigned int)caller);
+	lock->owner_cpu = cpu;
+}
+
+int _spin_trylock(spinlock_t *lock)
+{
+	unsigned long val, caller;
+	int cpu = smp_processor_id();
+
+	GET_CALLER(caller);
+	__asm__ __volatile__("ldstub [%1], %0"
+			     : "=r" (val)
+			     : "r" (&(lock->lock))
+			     : "memory");
+	membar("#StoreLoad | #StoreStore");
+	if (!val) {
+		lock->owner_pc = ((unsigned int)caller);
+		lock->owner_cpu = cpu;
+	}
+	return val == 0;
+}
+
+void _do_spin_unlock(spinlock_t *lock)
+{
+	lock->owner_pc = 0;
+	lock->owner_cpu = NO_PROC_ID;
+	membar("#StoreStore | #LoadStore");
+	lock->lock = 0;
+}
+
+/* Keep INIT_STUCK the same... */
+
+void _do_read_lock (rwlock_t *rw, char *str)
+{
+	unsigned long caller, val;
+	int stuck = INIT_STUCK;
+	int cpu = smp_processor_id();
+
+	GET_CALLER(caller);
+wlock_again:
+	/* Wait for any writer to go away.  */
+	while (((long)(rw->lock)) < 0) {
+		if (!--stuck) {
+			show_read(str, rw, caller);
+			stuck = INIT_STUCK;
+		}
+		membar("#LoadLoad");
+	}
+	/* Try once to increment the counter.  */
+	__asm__ __volatile__("
+	ldx		[%0], %%g5
+	brlz,a,pn	%%g5, 2f
+	 mov		1, %0
+	add		%%g5, 1, %%g7
+	casx		[%0], %%g5, %%g7
+	sub		%%g5, %%g7, %0
+2:"	: "=r" (val)
+	: "0" (&(rw->lock))
+	: "g5", "g7", "memory");
+	membar("#StoreLoad | #StoreStore");
+	if (val)
+		goto wlock_again;
+	rw->reader_pc[cpu] = ((unsigned int)caller);
+}
+
+void _do_read_unlock (rwlock_t *rw, char *str)
+{
+	unsigned long caller, val;
+	int stuck = INIT_STUCK;
+	int cpu = smp_processor_id();
+
+	GET_CALLER(caller);
+
+	/* Drop our identity _first_. */
+	rw->reader_pc[cpu] = 0;
+runlock_again:
+	/* Spin trying to decrement the counter using casx.  */
+	__asm__ __volatile__("
+	ldx	[%0], %%g5
+	sub	%%g5, 1, %%g7
+	casx	[%0], %%g5, %%g7
+	membar	#StoreLoad | #StoreStore
+	sub	%%g5, %%g7, %0
+"	: "=r" (val)
+	: "0" (&(rw->lock))
+	: "g5", "g7", "memory");
+	if (val) {
+		if (!--stuck) {
+			show_read(str, rw, caller);
+			stuck = INIT_STUCK;
+		}
+		goto runlock_again;
+	}
+}
+
+void _do_write_lock (rwlock_t *rw, char *str)
+{
+	unsigned long caller, val;
+	int stuck = INIT_STUCK;
+	int cpu = smp_processor_id();
+
+	GET_CALLER(caller);
+wlock_again:
+	/* Spin while there is another writer. */
+	while (((long)rw->lock) < 0) {
+		if (!--stuck) {
+			show_write(str, rw, caller);
+			stuck = INIT_STUCK;
+		}
+		membar("#LoadLoad");
+	}
+
+	/* Try to acuire the write bit.  */
+	__asm__ __volatile__("
+	mov	1, %%g3
+	sllx	%%g3, 63, %%g3
+	ldx	[%0], %%g5
+	brlz,pn	%%g5, 1f
+	 or	%%g5, %%g3, %%g7
+	casx	[%0], %%g5, %%g7
+	membar	#StoreLoad | #StoreStore
+	ba,pt	%%xcc, 2f
+	 sub	%%g5, %%g7, %0
+1:	mov	1, %0
+2:"	: "=r" (val)
+	: "0" (&(rw->lock))
+	: "g3", "g5", "g7", "memory");
+	if (val) {
+		/* We couldn't get the write bit. */
+		if (!--stuck) {
+			show_write(str, rw, caller);
+			stuck = INIT_STUCK;
+		}
+		goto wlock_again;
+	}
+	if ((rw->lock & ((1UL<<63)-1UL)) != 0UL) {
+		/* Readers still around, drop the write
+		 * lock, spin, and try again.
+		 */
+		if (!--stuck) {
+			show_write(str, rw, caller);
+			stuck = INIT_STUCK;
+		}
+		__asm__ __volatile__("
+		mov	1, %%g3
+		sllx	%%g3, 63, %%g3
+1:		ldx	[%0], %%g5
+		andn	%%g5, %%g3, %%g7
+		casx	[%0], %%g5, %%g7
+		cmp	%%g5, %%g7
+		bne,pn	%%xcc, 1b
+		 membar	#StoreLoad | #StoreStore"
+		: /* no outputs */
+		: "r" (&(rw->lock))
+		: "g3", "g5", "g7", "cc", "memory");
+		while(rw->lock != 0) {
+			if (!--stuck) {
+				show_write(str, rw, caller);
+				stuck = INIT_STUCK;
+			}
+			membar("#LoadLoad");
+		}
+		goto wlock_again;
+	}
+
+	/* We have it, say who we are. */
+	rw->writer_pc = ((unsigned int)caller);
+	rw->writer_cpu = cpu;
+}
+
+void _do_write_unlock(rwlock_t *rw)
+{
+	unsigned long caller, val;
+	int stuck = INIT_STUCK;
+
+	GET_CALLER(caller);
+
+	/* Drop our identity _first_ */
+	rw->writer_pc = 0;
+	rw->writer_cpu = NO_PROC_ID;
+wlock_again:
+	__asm__ __volatile__("
+	mov	1, %%g3
+	sllx	%%g3, 63, %%g3
+	ldx	[%0], %%g5
+	andn	%%g5, %%g3, %%g7
+	casx	[%0], %%g5, %%g7
+	membar	#StoreLoad | #StoreStore
+	sub	%%g5, %%g7, %0
+"	: "=r" (val)
+	: "0" (&(rw->lock))
+	: "g3", "g5", "g7", "memory");
+	if (val) {
+		if (!--stuck) {
+			show_write("write_unlock", rw, caller);
+			stuck = INIT_STUCK;
+		}
+		goto wlock_again;
+	}
+}
+
+#endif /* SPIN_LOCK_DEBUG */
+#endif /* __SMP__ */