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>
diff --git a/lib/idr.c b/lib/idr.c
index e15502e..db040ce 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 @@
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
*