s390/rwlock: use the interlocked-access facility 1 instructions
Make use of the load-and-add, load-and-or and load-and-and instructions
to atomically update the read-write lock without a compare-and-swap loop.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h
index f9537b9..d6bdf90 100644
--- a/arch/s390/include/asm/spinlock.h
+++ b/arch/s390/include/asm/spinlock.h
@@ -130,8 +130,6 @@
*/
#define arch_write_can_lock(x) ((x)->lock == 0)
-extern void _raw_read_lock_wait(arch_rwlock_t *lp);
-extern void _raw_write_lock_wait(arch_rwlock_t *lp);
extern int _raw_read_trylock_retry(arch_rwlock_t *lp);
extern int _raw_write_trylock_retry(arch_rwlock_t *lp);
@@ -152,6 +150,78 @@
_raw_compare_and_swap(&rw->lock, 0, 0x80000000));
}
+#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
+
+#define __RAW_OP_OR "lao"
+#define __RAW_OP_AND "lan"
+#define __RAW_OP_ADD "laa"
+
+#define __RAW_LOCK(ptr, op_val, op_string) \
+({ \
+ unsigned int old_val; \
+ \
+ typecheck(unsigned int *, ptr); \
+ asm volatile( \
+ op_string " %0,%2,%1\n" \
+ "bcr 14,0\n" \
+ : "=d" (old_val), "+Q" (*ptr) \
+ : "d" (op_val) \
+ : "cc", "memory"); \
+ old_val; \
+})
+
+#define __RAW_UNLOCK(ptr, op_val, op_string) \
+({ \
+ unsigned int old_val; \
+ \
+ typecheck(unsigned int *, ptr); \
+ asm volatile( \
+ "bcr 14,0\n" \
+ op_string " %0,%2,%1\n" \
+ : "=d" (old_val), "+Q" (*ptr) \
+ : "d" (op_val) \
+ : "cc", "memory"); \
+ old_val; \
+})
+
+extern void _raw_read_lock_wait(arch_rwlock_t *lp);
+extern void _raw_write_lock_wait(arch_rwlock_t *lp, unsigned int prev);
+
+static inline void arch_read_lock(arch_rwlock_t *rw)
+{
+ unsigned int old;
+
+ old = __RAW_LOCK(&rw->lock, 1, __RAW_OP_ADD);
+ if ((int) old < 0)
+ _raw_read_lock_wait(rw);
+}
+
+static inline void arch_read_unlock(arch_rwlock_t *rw)
+{
+ __RAW_UNLOCK(&rw->lock, -1, __RAW_OP_ADD);
+}
+
+static inline void arch_write_lock(arch_rwlock_t *rw)
+{
+ unsigned int old;
+
+ old = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR);
+ if (old != 0)
+ _raw_write_lock_wait(rw, old);
+ rw->owner = SPINLOCK_LOCKVAL;
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *rw)
+{
+ rw->owner = 0;
+ __RAW_UNLOCK(&rw->lock, 0x7fffffff, __RAW_OP_AND);
+}
+
+#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
+
+extern void _raw_read_lock_wait(arch_rwlock_t *lp);
+extern void _raw_write_lock_wait(arch_rwlock_t *lp);
+
static inline void arch_read_lock(arch_rwlock_t *rw)
{
if (!arch_read_trylock_once(rw))
@@ -187,6 +257,8 @@
: "cc", "memory");
}
+#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
+
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
if (!arch_read_trylock_once(rw))