#define __LINUX_SEQLOCK_H
/*
* Reader/writer consistent mechanism without starving writers. This type of
- * lock for data where the reader wants a consitent set of information
+ * lock for data where the reader wants a consistent set of information
* and is willing to retry if the information changes. Readers never
* block but they may have to retry if a writer is in
* progress. Writers do not wait for readers.
* by Keith Owens and Andrea Arcangeli
*/
-#include <linux/config.h>
#include <linux/spinlock.h>
#include <linux/preempt.h>
* These macros triggered gcc-3.x compile-time problems. We think these are
* OK now. Be cautious.
*/
-#define SEQLOCK_UNLOCKED { 0, SPIN_LOCK_UNLOCKED }
-#define seqlock_init(x) do { *(x) = (seqlock_t) SEQLOCK_UNLOCKED; } while (0)
+#define __SEQLOCK_UNLOCKED(lockname) \
+ { 0, __SPIN_LOCK_UNLOCKED(lockname) }
+#define SEQLOCK_UNLOCKED \
+ __SEQLOCK_UNLOCKED(old_style_seqlock_init)
+
+#define seqlock_init(x) \
+ do { \
+ (x)->sequence = 0; \
+ spin_lock_init(&(x)->lock); \
+ } while (0)
+
+#define DEFINE_SEQLOCK(x) \
+ seqlock_t x = __SEQLOCK_UNLOCKED(x)
/* Lock out other writers and update the count.
* Acts like a normal spin_lock/unlock.
{
spin_lock(&sl->lock);
++sl->sequence;
- smp_wmb();
-}
+ smp_wmb();
+}
-static inline void write_sequnlock(seqlock_t *sl)
+static inline void write_sequnlock(seqlock_t *sl)
{
smp_wmb();
sl->sequence++;
if (ret) {
++sl->sequence;
- smp_wmb();
+ smp_wmb();
}
return ret;
}
/* Start of read calculation -- fetch last complete writer token */
-static inline unsigned read_seqbegin(const seqlock_t *sl)
+static __always_inline unsigned read_seqbegin(const seqlock_t *sl)
{
unsigned ret = sl->sequence;
smp_rmb();
*
* Using xor saves one conditional branch.
*/
-static inline int read_seqretry(const seqlock_t *sl, unsigned iv)
+static __always_inline int read_seqretry(const seqlock_t *sl, unsigned iv)
{
smp_rmb();
return (iv & 1) | (sl->sequence ^ iv);