I wanted to wrap a bunch of ida_simple_get calls into their own
locking, until I dug around and read the original commit message.
Stuff like this should imo be added to the kernel doc, let's do that.
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
lib/idr.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/lib/idr.c b/lib/idr.c
index 6098336df267..5508d7f6d7be 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -927,6 +927,9 @@ EXPORT_SYMBOL(ida_pre_get);
* and go back to the ida_pre_get() call. If the ida is full, it will
* return %-ENOSPC.
*
+ * Note that callers must ensure that concurrent access to @ida is not possible.
+ * When simplicity trumps concurrency needs look at ida_simple_get() instead.
+ *
* @p_id returns a value in the range @starting_id ... %0x7fffffff.
*/
int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
@@ -1073,6 +1076,10 @@ EXPORT_SYMBOL(ida_destroy);
* Allocates an id in the range start <= id < end, or returns -ENOSPC.
* On memory allocation failure, returns -ENOMEM.
*
+ * Compared to ida_get_new_above() this function does its own locking and hence
+ * is recommended everywhere where simplicity is preferred over the last bit of
+ * speed.
+ *
* Use ida_simple_remove() to get rid of an id.
*/
int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
@@ -1119,6 +1126,13 @@ EXPORT_SYMBOL(ida_simple_get);
* ida_simple_remove - remove an allocated id.
* @ida: the (initialized) ida.
* @id: the id returned by ida_simple_get.
+ *
+ * Use to release an id allocated with ida_simple_get().
+ *
+ * Compared to ida_get_new_above() this function does its own locking and hence
+ * is recommended everywhere where simplicity is preferred over the last bit of
+ * speed.
+ *
*/
void ida_simple_remove(struct ida *ida, unsigned int id)
{
--
2.10.1
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