[SPARC64]: Get preempt building and working again.

- HAVE_DEC_LOCK depends on SMP
- Trap return preemption check needs interrupt disabled check
- Implement write_trylock
- Fix in_atomic() definition when PREEMPT enabled

arch/sparc64/Kconfig

@@ -813,7 +813,7 @@ config DEBUG_SPINLOCK
 # the generic version in that case.
 config HAVE_DEC_LOCK
 	bool
-	depends on !DEBUG_SPINLOCK
+	depends on SMP && !DEBUG_SPINLOCK
 	default y
 
 config DEBUG_SPINLOCK_SLEEP

arch/sparc64/kernel/rtrap.S

@@ -270,9 +270,14 @@ to_kernel:
 #ifdef CONFIG_PREEMPT
 		ldsw			[%g6 + TI_PRE_COUNT], %l5
 		brnz			%l5, kern_fpucheck
+		 ldx			[%g6 + TI_FLAGS], %l5
+		andcc			%l5, _TIF_NEED_RESCHED, %g0
+		be,pt			%xcc, kern_fpucheck
+		 srl			%l4, 20, %l5
+		cmp			%l5, 0
+		bne,pn			%xcc, kern_fpucheck
 		 sethi			%hi(PREEMPT_ACTIVE), %l6
 		stw			%l6, [%g6 + TI_PRE_COUNT]
-		wrpr			0, %pil
 		call			schedule
 		 nop
 		ba,pt			%xcc, rtrap

arch/sparc64/kernel/sparc64_ksyms.c

@@ -136,6 +136,7 @@ EXPORT_SYMBOL(__read_lock);
 EXPORT_SYMBOL(__read_unlock);
 EXPORT_SYMBOL(__write_lock);
 EXPORT_SYMBOL(__write_unlock);
+EXPORT_SYMBOL(__write_trylock);
 #endif
 
 /* Hard IRQ locking */

arch/sparc64/lib/rwlock.S

@@ -63,5 +63,27 @@ __write_lock: /* %o0 = lock_ptr */
 	be,pt		%icc, 99b
 	 membar		#StoreLoad | #StoreStore
 	ba,a,pt		%xcc, 1b
+
+	.globl		__write_trylock
+__write_trylock: /* %o0 = lock_ptr */
+	sethi		%hi(0x80000000), %g2
+1:	lduw		[%o0], %g5
+	brnz,pn		%g5, __write_trylock_fail
+4:	 or		%g5, %g2, %g7
+
+	cas		[%o0], %g5, %g7
+	cmp		%g5, %g7
+	be,pt		%icc, __write_trylock_succeed
+	 membar		#StoreLoad | #StoreStore
+
+	ba,pt		%xcc, 1b
+	 nop
+__write_trylock_succeed:
+	retl
+	 mov		1, %o0
+
+__write_trylock_fail:
+	retl
+	 mov		0, %o0
 rwlock_impl_end:
 

include/asm-sparc64/hardirq.h

@@ -79,7 +79,8 @@ typedef struct {
 #define irq_enter()		(preempt_count() += HARDIRQ_OFFSET)
 
 #ifdef CONFIG_PREEMPT
-# define in_atomic()	(preempt_count() != kernel_locked())
+# include <linux/smp_lock.h>
+# define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != kernel_locked())
 # define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
 #else
 # define in_atomic()	(preempt_count() != 0)

include/asm-sparc64/spinlock.h

@@ -118,11 +118,13 @@ extern void __read_lock(rwlock_t *);
 extern void __read_unlock(rwlock_t *);
 extern void __write_lock(rwlock_t *);
 extern void __write_unlock(rwlock_t *);
+extern int __write_trylock(rwlock_t *);
 
 #define _raw_read_lock(p)	__read_lock(p)
 #define _raw_read_unlock(p)	__read_unlock(p)
 #define _raw_write_lock(p)	__write_lock(p)
 #define _raw_write_unlock(p)	__write_unlock(p)
+#define _raw_write_trylock(p)	__write_trylock(p)
 
 #else /* !(CONFIG_DEBUG_SPINLOCK) */