diff options
author | Hugh Dickins <hughd@google.com> | 2012-03-21 19:34:20 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-21 20:55:01 -0400 |
commit | 9f7de8275b46d9d11b1505adbfe6c2bb48df4741 (patch) | |
tree | 7495111b20585e6e4da20d1b46b7a3747903ce2a /lib/idr.c | |
parent | 0e79dedde951e981612ed4e6d74873d61d2a113b (diff) |
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>
Diffstat (limited to 'lib/idr.c')
-rw-r--r-- | lib/idr.c | 8 |
1 files changed, 5 insertions, 3 deletions
@@ -595,8 +595,10 @@ EXPORT_SYMBOL(idr_for_each); | |||
595 | * Returns pointer to registered object with id, which is next number to | 595 | * Returns pointer to registered object with id, which is next number to |
596 | * given id. After being looked up, *@nextidp will be updated for the next | 596 | * given id. After being looked up, *@nextidp will be updated for the next |
597 | * iteration. | 597 | * iteration. |
598 | * | ||
599 | * This function can be called under rcu_read_lock(), given that the leaf | ||
600 | * pointers lifetimes are correctly managed. | ||
598 | */ | 601 | */ |
599 | |||
600 | void *idr_get_next(struct idr *idp, int *nextidp) | 602 | void *idr_get_next(struct idr *idp, int *nextidp) |
601 | { | 603 | { |
602 | struct idr_layer *p, *pa[MAX_LEVEL]; | 604 | struct idr_layer *p, *pa[MAX_LEVEL]; |
@@ -605,11 +607,11 @@ void *idr_get_next(struct idr *idp, int *nextidp) | |||
605 | int n, max; | 607 | int n, max; |
606 | 608 | ||
607 | /* find first ent */ | 609 | /* find first ent */ |
608 | n = idp->layers * IDR_BITS; | ||
609 | max = 1 << n; | ||
610 | p = rcu_dereference_raw(idp->top); | 610 | p = rcu_dereference_raw(idp->top); |
611 | if (!p) | 611 | if (!p) |
612 | return NULL; | 612 | return NULL; |
613 | n = (p->layer + 1) * IDR_BITS; | ||
614 | max = 1 << n; | ||
613 | 615 | ||
614 | while (id < max) { | 616 | while (id < max) { |
615 | while (n > 0 && p) { | 617 | while (n > 0 && p) { |