diff options
| author | Hugh Dickins <hughd@google.com> | 2012-03-21 16:34:20 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-03-06 03:24:16 +0000 |
| commit | 6195dff3efda58746096daf01c3dbb74015dc0b5 (patch) | |
| tree | 7e80d36602d78ced512e3688779debd38abe4e4d | |
| parent | 507b2ac935cfe53dbe3a61d61254154e4829c2e4 (diff) | |
idr: make idr_get_next() good for rcu_read_lock()
commit 9f7de8275b46d9d11b1505adbfe6c2bb48df4741 upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | lib/idr.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/lib/idr.c b/lib/idr.c index f87af03245f3..e0761f7ba7e3 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) { |