path: root/lib/idr.c
diff options
authorAndrew Morton <akpm@linux-foundation.org>2009-01-15 13:51:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-15 16:39:40 -0800
commit5b019e99016f3a692ba45bf68fba73a402d7c01a (patch)
treea419c318c550dd2edaa03185477e162e0c7d8e77 /lib/idr.c
parent5da7f3d71e243ef5c464967581414d29c72bab75 (diff)
lib/idr.c: use kmem_cache_zalloc() for the idr_layer cache
David points out that the idr_remove_all() function returns unused slabs to the kmem cache, but needs to zero them first or else they will be uninitialized upon next use. This causes crashes which have been observed in the firewire subsystem. He fixed this by zeroing the object before freeing it in idr_remove_all(). But we agree that simply removing the constructor and zeroing the object at allocation time is simpler than relying upon slab constructor machinery and might even be faster. This problem was introduced by "idr: make idr_remove rcu-safe" (commit cf481c20c476ad2c0febdace9ce23f5a4db19582), which was first released in 2.6.27. There are no known codesites which trigger this bug in 2.6.27 or 2.6.28. The post-2.6.28 firewire changes are the only known triggerer. There might of course be not-yet-discovered triggerers in 2.6.27 and 2.6.28, and there might be out-of-tree triggerers which are added to those kernel versions. I'll let the -stable guys decide whether they want to backport this fix. Reported-by: David Moore <dcm@acm.org> Cc: Stefan Richter <stefanr@s5r6.in-berlin.de> Cc: Nadia Derbey <Nadia.Derbey@bull.net> Cc: Paul E. McKenney <paulmck@us.ibm.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Kristian Hgsberg <krh@redhat.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Cc: <stable@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')
1 files changed, 2 insertions, 8 deletions
diff --git a/lib/idr.c b/lib/idr.c
index 6b7cfa6508f..c11c5765cde 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -121,7 +121,7 @@ int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
while (idp->id_free_cnt < IDR_FREE_MAX) {
struct idr_layer *new;
- new = kmem_cache_alloc(idr_layer_cache, gfp_mask);
+ new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
if (new == NULL)
return (0);
move_to_free_list(idp, new);
@@ -623,16 +623,10 @@ void *idr_replace(struct idr *idp, void *ptr, int id)
-static void idr_cache_ctor(void *idr_layer)
- memset(idr_layer, 0, sizeof(struct idr_layer));
void __init idr_init_cache(void)
idr_layer_cache = kmem_cache_create("idr_layer_cache",
- sizeof(struct idr_layer), 0, SLAB_PANIC,
- idr_cache_ctor);
+ sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);