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authorRusty Russell <rusty@rustcorp.com.au>2011-08-03 16:21:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-08-03 14:25:20 -1000
commit88eca0207cf1574328c3ce8c3be537a9317261bb (patch)
tree155b13f5df1e239fea2ad5512ef5b19865de4a9e
parenta7295898a1d2e501427f557111c2b4bdfc90b1ed (diff)
downloadlinux-linaro-stable-88eca0207cf1574328c3ce8c3be537a9317261bb.tar.gz
ida: simplified functions for id allocation
The current hyper-optimized functions are overkill if you simply want to allocate an id for a device. Create versions which use an internal lock. In followup patches, numerous drivers are converted to use this interface. Thanks to Tejun for feedback. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/idr.h4
-rw-r--r--lib/idr.c67
2 files changed, 71 insertions, 0 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h
index 13a801f3d028..255491cf522e 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -146,6 +146,10 @@ void ida_remove(struct ida *ida, int id);
void ida_destroy(struct ida *ida);
void ida_init(struct ida *ida);
+int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
+ gfp_t gfp_mask);
+void ida_simple_remove(struct ida *ida, unsigned int id);
+
void __init idr_init_cache(void);
#endif /* __IDR_H__ */
diff --git a/lib/idr.c b/lib/idr.c
index e15502e8b21e..db040ce3fa73 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -34,8 +34,10 @@
#include <linux/err.h>
#include <linux/string.h>
#include <linux/idr.h>
+#include <linux/spinlock.h>
static struct kmem_cache *idr_layer_cache;
+static DEFINE_SPINLOCK(simple_ida_lock);
static struct idr_layer *get_from_free_list(struct idr *idp)
{
@@ -926,6 +928,71 @@ void ida_destroy(struct ida *ida)
EXPORT_SYMBOL(ida_destroy);
/**
+ * ida_simple_get - get a new id.
+ * @ida: the (initialized) ida.
+ * @start: the minimum id (inclusive, < 0x8000000)
+ * @end: the maximum id (exclusive, < 0x8000000 or 0)
+ * @gfp_mask: memory allocation flags
+ *
+ * Allocates an id in the range start <= id < end, or returns -ENOSPC.
+ * On memory allocation failure, returns -ENOMEM.
+ *
+ * Use ida_simple_remove() to get rid of an id.
+ */
+int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
+ gfp_t gfp_mask)
+{
+ int ret, id;
+ unsigned int max;
+
+ BUG_ON((int)start < 0);
+ BUG_ON((int)end < 0);
+
+ if (end == 0)
+ max = 0x80000000;
+ else {
+ BUG_ON(end < start);
+ max = end - 1;
+ }
+
+again:
+ if (!ida_pre_get(ida, gfp_mask))
+ return -ENOMEM;
+
+ spin_lock(&simple_ida_lock);
+ ret = ida_get_new_above(ida, start, &id);
+ if (!ret) {
+ if (id > max) {
+ ida_remove(ida, id);
+ ret = -ENOSPC;
+ } else {
+ ret = id;
+ }
+ }
+ spin_unlock(&simple_ida_lock);
+
+ if (unlikely(ret == -EAGAIN))
+ goto again;
+
+ return ret;
+}
+EXPORT_SYMBOL(ida_simple_get);
+
+/**
+ * ida_simple_remove - remove an allocated id.
+ * @ida: the (initialized) ida.
+ * @id: the id returned by ida_simple_get.
+ */
+void ida_simple_remove(struct ida *ida, unsigned int id)
+{
+ BUG_ON((int)id < 0);
+ spin_lock(&simple_ida_lock);
+ ida_remove(ida, id);
+ spin_unlock(&simple_ida_lock);
+}
+EXPORT_SYMBOL(ida_simple_remove);
+
+/**
* ida_init - initialize ida handle
* @ida: ida handle
*