+/*
+ * percpu partition lock
+ *
+ * There are some use-cases like this in Lustre:
+ * . each CPU partition has it's own private data which is frequently changed,
+ * and mostly by the local CPU partition.
+ * . all CPU partitions share some global data, these data are rarely changed.
+ *
+ * LNet is typical example.
+ * CPU partition lock is designed for this kind of use-cases:
+ * . each CPU partition has it's own private lock
+ * . change on private data just needs to take the private lock
+ * . read on shared data just needs to take _any_ of private locks
+ * . change on shared data needs to take _all_ private locks,
+ * which is slow and should be really rare.
+ */
+
+enum {
+ CFS_PERCPT_LOCK_EX = -1, /* negative */
+};
+
+#ifdef __KERNEL__
+
+struct cfs_percpt_lock {
+ /* cpu-partition-table for this lock */
+ struct cfs_cpt_table *pcl_cptab;
+ /* exclusively locked */
+ unsigned int pcl_locked;
+ /* private lock table */
+ spinlock_t **pcl_locks;
+};
+
+/* return number of private locks */
+static inline int
+cfs_percpt_lock_num(struct cfs_percpt_lock *pcl)
+{
+ return cfs_cpt_number(pcl->pcl_cptab);
+}
+
+#else /* !__KERNEL__ */
+
+# ifdef HAVE_LIBPTHREAD
+
+struct cfs_percpt_lock {
+ pthread_mutex_t pcl_mutex;
+};
+
+# else /* !HAVE_LIBPTHREAD */
+
+struct cfs_percpt_lock {
+ int pcl_lock;
+};
+
+static const struct cfs_percpt_lock CFS_PERCPT_LOCK_MAGIC;
+
+# endif /* HAVE_LIBPTHREAD */
+# define cfs_percpt_lock_num(pcl) 1
+#endif /* __KERNEL__ */
+
+/*
+ * create a cpu-partition lock based on CPU partition table \a cptab,
+ * each private lock has extra \a psize bytes padding data
+ */
+struct cfs_percpt_lock *cfs_percpt_lock_alloc(struct cfs_cpt_table *cptab);
+/* destroy a cpu-partition lock */
+void cfs_percpt_lock_free(struct cfs_percpt_lock *pcl);
+
+/* lock private lock \a index of \a pcl */
+void cfs_percpt_lock(struct cfs_percpt_lock *pcl, int index);
+/* unlock private lock \a index of \a pcl */
+void cfs_percpt_unlock(struct cfs_percpt_lock *pcl, int index);
+/* create percpt (atomic) refcount based on @cptab */
+atomic_t **cfs_percpt_atomic_alloc(struct cfs_cpt_table *cptab, int val);
+/* destroy percpt refcount */
+void cfs_percpt_atomic_free(atomic_t **refs);
+/* return sum of all percpu refs */
+int cfs_percpt_atomic_summary(atomic_t **refs);
+
+