aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorHugh Dickins <hughd@google.com>2012-03-21 16:34:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:55:01 -0700
commit9f7de8275b46d9d11b1505adbfe6c2bb48df4741 (patch)
tree7495111b20585e6e4da20d1b46b7a3747903ce2a
parent0e79dedde951e981612ed4e6d74873d61d2a113b (diff)
downloadlinux-linaro-stable-9f7de8275b46d9d11b1505adbfe6c2bb48df4741.tar.gz
idr: make idr_get_next() good for rcu_read_lock()
Make one small adjustment to idr_get_next(): take the height from the top layer (stable under RCU) instead of from the root (unprotected by RCU), as idr_find() does: so that it can be used with RCU locking. Copied comment on RCU locking from idr_find(). Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/idr.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/lib/idr.c b/lib/idr.c
index ed055b297c81..12499ba7967e 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -595,8 +595,10 @@ EXPORT_SYMBOL(idr_for_each);
* Returns pointer to registered object with id, which is next number to
* given id. After being looked up, *@nextidp will be updated for the next
* iteration.
+ *
+ * This function can be called under rcu_read_lock(), given that the leaf
+ * pointers lifetimes are correctly managed.
*/
-
void *idr_get_next(struct idr *idp, int *nextidp)
{
struct idr_layer *p, *pa[MAX_LEVEL];
@@ -605,11 +607,11 @@ void *idr_get_next(struct idr *idp, int *nextidp)
int n, max;
/* find first ent */
- n = idp->layers * IDR_BITS;
- max = 1 << n;
p = rcu_dereference_raw(idp->top);
if (!p)
return NULL;
+ n = (p->layer + 1) * IDR_BITS;
+ max = 1 << n;
while (id < max) {
while (n > 0 && p) {