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-rw-r--r--include/linux/rwsem.h16
1 files changed, 9 insertions, 7 deletions
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 2ea18a3def04..e401358c4e7e 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -34,12 +34,13 @@
*/
struct rw_semaphore {
atomic_long_t count;
-#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
/*
- * Write owner. Used as a speculative check to see
- * if the owner is running on the cpu.
+ * Write owner or one of the read owners as well flags regarding
+ * the current state of the rwsem. Can be used as a speculative
+ * check to see if the write owner is running on the cpu.
*/
- struct task_struct *owner;
+ atomic_long_t owner;
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
struct optimistic_spin_queue osq; /* spinner MCS lock */
#endif
raw_spinlock_t wait_lock;
@@ -50,10 +51,10 @@ struct rw_semaphore {
};
/*
- * Setting bit 1 of the owner field but not bit 0 will indicate
+ * Setting all bits of the owner field except bit 0 will indicate
* that the rwsem is writer-owned with an unknown owner.
*/
-#define RWSEM_OWNER_UNKNOWN ((struct task_struct *)-2L)
+#define RWSEM_OWNER_UNKNOWN (-2L)
/* In all implementations count != 0 means locked */
static inline int rwsem_is_locked(struct rw_semaphore *sem)
@@ -73,13 +74,14 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
#endif
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
-#define __RWSEM_OPT_INIT(lockname) , .osq = OSQ_LOCK_UNLOCKED, .owner = NULL
+#define __RWSEM_OPT_INIT(lockname) , .osq = OSQ_LOCK_UNLOCKED
#else
#define __RWSEM_OPT_INIT(lockname)
#endif
#define __RWSEM_INITIALIZER(name) \
{ __RWSEM_INIT_COUNT(name), \
+ .owner = ATOMIC_LONG_INIT(0), \
.wait_list = LIST_HEAD_INIT((name).wait_list), \
.wait_lock = __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock) \
__RWSEM_OPT_INIT(name) \