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authorTejun Heo <tj@kernel.org>2013-02-27 17:05:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-27 19:10:20 -0800
commite8c8d1bc063bc88cfa1356266027b5075d3a82d7 (patch)
treeb657e3a3aa9eb8499690bb2fc0cbd908cdd2a334 /lib
parent326cf0f0f308933c10236280a322031f0097205d (diff)
downloadvexpress-lsk-e8c8d1bc063bc88cfa1356266027b5075d3a82d7.tar.gz
idr: remove MAX_IDR_MASK and move left MAX_IDR_* into idr.c
MAX_IDR_MASK is another weirdness in the idr interface. As idr covers whole positive integer range, it's defined as 0x7fffffff or INT_MAX. Its usage in idr_find(), idr_replace() and idr_remove() is bizarre. They basically mask off the sign bit and operate on the rest, so if the caller, by accident, passes in a negative number, the sign bit will be masked off and the remaining part will be used as if that was the input, which is worse than crashing. The constant is visible in idr.h and there are several users in the kernel. * drivers/i2c/i2c-core.c:i2c_add_numbered_adapter() Basically used to test if adap->nr is a negative number which isn't -1 and returns -EINVAL if so. idr_alloc() already has negative @start checking (w/ WARN_ON_ONCE), so this can go away. * drivers/infiniband/core/cm.c:cm_alloc_id() drivers/infiniband/hw/mlx4/cm.c:id_map_alloc() Used to wrap cyclic @start. Can be replaced with max(next, 0). Note that this type of cyclic allocation using idr is buggy. These are prone to spurious -ENOSPC failure after the first wraparound. * fs/super.c:get_anon_bdev() The ID allocated from ida is masked off before being tested whether it's inside valid range. ida allocated ID can never be a negative number and the masking is unnecessary. Update idr_*() functions to fail with -EINVAL when negative @id is specified and update other MAX_IDR_MASK users as described above. This leaves MAX_IDR_MASK without any user, remove it and relocate other MAX_IDR_* constants to lib/idr.c. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jean Delvare <khali@linux-fr.org> Cc: Roland Dreier <roland@kernel.org> Cc: Sean Hefty <sean.hefty@intel.com> Cc: Hal Rosenstock <hal.rosenstock@gmail.com> Cc: "Marciniszyn, Mike" <mike.marciniszyn@intel.com> Cc: Jack Morgenstein <jackm@dev.mellanox.co.il> Cc: Or Gerlitz <ogerlitz@mellanox.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Wolfram Sang <wolfram@the-dreams.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/idr.c24
1 files changed, 17 insertions, 7 deletions
diff --git a/lib/idr.c b/lib/idr.c
index 63dda62131b..e2b799989ab 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -38,6 +38,15 @@
#include <linux/percpu.h>
#include <linux/hardirq.h>
+#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
+#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
+
+/* Leave the possibility of an incomplete final layer */
+#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
+
+/* Number of id_layer structs to leave in free list */
+#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
+
static struct kmem_cache *idr_layer_cache;
static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head);
static DEFINE_PER_CPU(int, idr_preload_cnt);
@@ -542,8 +551,8 @@ void idr_remove(struct idr *idp, int id)
struct idr_layer *p;
struct idr_layer *to_free;
- /* Mask off upper bits we don't use for the search. */
- id &= MAX_IDR_MASK;
+ if (WARN_ON_ONCE(id < 0))
+ return;
sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
@@ -650,14 +659,14 @@ void *idr_find(struct idr *idp, int id)
int n;
struct idr_layer *p;
+ if (WARN_ON_ONCE(id < 0))
+ return NULL;
+
p = rcu_dereference_raw(idp->top);
if (!p)
return NULL;
n = (p->layer+1) * IDR_BITS;
- /* Mask off upper bits we don't use for the search. */
- id &= MAX_IDR_MASK;
-
if (id > idr_max(p->layer + 1))
return NULL;
BUG_ON(n == 0);
@@ -799,14 +808,15 @@ void *idr_replace(struct idr *idp, void *ptr, int id)
int n;
struct idr_layer *p, *old_p;
+ if (WARN_ON_ONCE(id < 0))
+ return ERR_PTR(-EINVAL);
+
p = idp->top;
if (!p)
return ERR_PTR(-EINVAL);
n = (p->layer+1) * IDR_BITS;
- id &= MAX_IDR_MASK;
-
if (id >= (1 << n))
return ERR_PTR(-EINVAL);