idr: revert misallocation bug fix

Commit 859ddf09743a8cc680af33f7259ccd0fd36bfe9d tried to fix
misallocation bug but broke full bit marking by not clearing
pa[idp->layers] and also is causing X failures due to lookup failure
in drm code.  The cause of the latter hasn't been found yet.  Revert
the fix for now.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/lib/idr.c b/lib/idr.c
index ba7d37cf7847..1cac726c44bc 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -140,7 +140,8 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
         id = *starting_id;
  restart:
         p = idp->top;
-        l = p->layer;
+        l = idp->layers;
+        pa[l--] = NULL;
         while (1) {
                 /*
                  * We run around this while until we reach the leaf node...
@@ -154,8 +155,8 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
                         oid = id;
                         id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
 
-                        /* did id go over the limit? */
-                        if (id >= (1 << (idp->layers * IDR_BITS))) {
+                        /* if already at the top layer, we need to grow */
+                        if (!(p = pa[l])) {
                                 *starting_id = id;
                                 return IDR_NEED_TO_GROW;
                         }