The patch titled
Subject: idr: make idr_get_next() good for rcu_read_lock()
has been added to the -mm tree. Its filename is
idr-make-idr_get_next-good-for-rcu_read_lock.patch
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From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/idr.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff -puN lib/idr.c~idr-make-idr_get_next-good-for-rcu_read_lock lib/idr.c
--- a/lib/idr.c~idr-make-idr_get_next-good-for-rcu_read_lock
+++ a/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
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) {
_
Subject: Subject: idr: make idr_get_next() good for rcu_read_lock()
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
proc-clear_refs-do-not-clear-reserved-pages.patch
mm-memcg-update-the-correct-soft-limit-tree-during-migration.patch
shm_unlock-fix-long-unpreemptible-section.patch
shm_unlock-fix-unevictable-pages-stranded-after-swap.patch
mm-fix-rss-count-leakage-during-migration.patch
mm-add-rss-counters-consistency-check.patch
mm-postpone-migrated-page-mapping-reset.patch
memcg-replace-mem_cont-by-mem_res_ctlr.patch
memcg-replace-mem-and-mem_cont-stragglers.patch
memcg-lru_size-instead-of-mem_cgroup_zstat.patch
memcg-enum-lru_list-lru.patch
memcg-remove-redundant-returns.patch
idr-make-idr_get_next-good-for-rcu_read_lock.patch
cgroup-revert-ss_id_lock-to-spinlock.patch
memcg-let-css_get_next-rely-upon-rcu_read_lock.patch
prio_tree-debugging-patch.patch
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