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Subject[patch 2/4 v2] percpu_ida: add percpu_ida_for_each_free
Add a new API to iterate free ids. blk-mq-tag will use it.

Note, this doesn't guarantee to iterate all free ids restrictly. Caller should
be aware of this. blk-mq uses it to do sanity check for request timedout, so
can tolerate the limitation.

Signed-off-by: Shaohua Li <shli@fusionio.com>
---
include/linux/percpu_ida.h | 4 ++++
lib/percpu_ida.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 48 insertions(+)

Index: master/include/linux/percpu_ida.h
===================================================================
--- master.orig/include/linux/percpu_ida.h 2013-10-15 08:28:36.198031207 +0800
+++ master/include/linux/percpu_ida.h 2013-10-15 08:30:19.996733244 +0800
@@ -73,4 +73,8 @@ static inline int percpu_ida_init(struct
IDA_DEFAULT_PCPU_BATCH_MOVE);
}

+typedef int (*percpu_ida_cb)(unsigned, void *);
+int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
+ void *data);
+
#endif /* __PERCPU_IDA_H__ */
Index: master/lib/percpu_ida.c
===================================================================
--- master.orig/lib/percpu_ida.c 2013-10-15 08:28:36.198031207 +0800
+++ master/lib/percpu_ida.c 2013-10-15 08:40:06.937353699 +0800
@@ -327,3 +327,47 @@ err:
return -ENOMEM;
}
EXPORT_SYMBOL_GPL(__percpu_ida_init);
+
+/**
+ * percpu_ida_for_each_free - iterate free ids of a pool
+ * @pool: pool to iterate
+ * @fn: interate callback function
+ * @data: parameter for @fn
+ *
+ * Note, this doesn't guarantee to iterate all free ids restrictly. Some free
+ * ids might be missed, some might be iterated duplicated, and some might
+ * be iterated and not free soon.
+ */
+int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
+ void *data)
+{
+ unsigned long flags;
+ struct percpu_ida_cpu *remote;
+ unsigned cpu, i, err = 0;
+
+ local_irq_save(flags);
+ for_each_possible_cpu(cpu) {
+ remote = per_cpu_ptr(pool->tag_cpu, cpu);
+ spin_lock(&remote->lock);
+ for (i = 0; i < remote->nr_free; i++) {
+ err = fn(remote->freelist[i], data);
+ if (err)
+ break;
+ }
+ spin_unlock(&remote->lock);
+ if (err)
+ goto out;
+ }
+
+ spin_lock(&pool->lock);
+ for (i = 0; i < pool->nr_free; i++) {
+ err = fn(pool->freelist[i], data);
+ if (err)
+ break;
+ }
+ spin_unlock(&pool->lock);
+out:
+ local_irq_restore(flags);
+ return err;
+}
+EXPORT_SYMBOL_GPL(percpu_ida_for_each_free);


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