locking/rwsem: Add CONFIG_RWSEM_SPIN_ON_OWNER
Just like with mutexes (CONFIG_MUTEX_SPIN_ON_OWNER),
encapsulate the dependencies for rwsem optimistic spinning.
No logical changes here as it continues to depend on both
SMP and the XADD algorithm variant.
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Jason Low <jason.low2@hp.com>
[ Also make it depend on ARCH_SUPPORTS_ATOMIC_RMW. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1405112406-13052-2-git-send-email-davidlohr@hp.com
Cc: aswin@hp.com
Cc: Chris Mason <clm@fb.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Josef Bacik <jbacik@fusionio.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 716807f..035d3c5 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -14,7 +14,9 @@
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
#include <linux/osq_lock.h>
+#endif
struct rw_semaphore;
@@ -26,7 +28,7 @@
long count;
struct list_head wait_list;
raw_spinlock_t wait_lock;
-#ifdef CONFIG_SMP
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
struct optimistic_spin_queue osq; /* spinner MCS lock */
/*
* Write owner. Used as a speculative check to see
@@ -63,7 +65,7 @@
# define __RWSEM_DEP_MAP_INIT(lockname)
#endif
-#if defined(CONFIG_SMP) && !defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
#define __RWSEM_OPT_INIT(lockname) , .osq = OSQ_LOCK_UNLOCKED, .owner = NULL
#else
#define __RWSEM_OPT_INIT(lockname)
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index 8190794..76768ee 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -227,6 +227,10 @@
def_bool y
depends on SMP && !DEBUG_MUTEXES && ARCH_SUPPORTS_ATOMIC_RMW
+config RWSEM_SPIN_ON_OWNER
+ def_bool y
+ depends on SMP && RWSEM_XCHGADD_ALGORITHM && ARCH_SUPPORTS_ATOMIC_RMW
+
config ARCH_USE_QUEUE_RWLOCK
bool
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 7190592..a2391ac 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -82,7 +82,7 @@
sem->count = RWSEM_UNLOCKED_VALUE;
raw_spin_lock_init(&sem->wait_lock);
INIT_LIST_HEAD(&sem->wait_list);
-#ifdef CONFIG_SMP
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
sem->owner = NULL;
osq_lock_init(&sem->osq);
#endif
@@ -262,7 +262,7 @@
return false;
}
-#ifdef CONFIG_SMP
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
/*
* Try to acquire write lock before the writer has been put on wait queue.
*/
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 42f806d..e2d3bc7 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -12,7 +12,7 @@
#include <linux/atomic.h>
-#if defined(CONFIG_SMP) && defined(CONFIG_RWSEM_XCHGADD_ALGORITHM)
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
static inline void rwsem_set_owner(struct rw_semaphore *sem)
{
sem->owner = current;
