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Message-ID: <20130208210234.GC26660@mtj.dyndns.org>
Date: Fri, 8 Feb 2013 13:02:34 -0800
From: Tejun Heo <tj@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH 3/6] idr: remove length restriction from idr_layer->bitmap
Currently, idr->bitmap is declared as an unsigned long which restricts
the number of bits an idr_layer can contain. All bitops can handle
arbitrary positive integer bit number and there's no reason for this
restriction.
Declare idr_layer->bitmap using DECLARE_BITMAP() instead of a single
unsigned long.
* idr_layer->bitmap is now an array. '&' dropped from params to
bitops.
* Replaced "== IDR_FULL" tests with bitmap_full() and removed
IDR_FULL.
* Replaced find_next_bit() on ~bitmap with find_next_zero_bit().
* Replaced "bitmap = 0" with bitmap_clear().
This patch doesn't (or at least shouldn't) introduce any behavior
changes.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
include/linux/idr.h | 12 +-----------
lib/idr.c | 34 +++++++++++++++++-----------------
2 files changed, 18 insertions(+), 28 deletions(-)
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -19,18 +19,8 @@
#if BITS_PER_LONG == 32
# define IDR_BITS 5
-# define IDR_FULL 0xfffffffful
-/* We can only use two of the bits in the top level because there is
- only one possible bit in the top level (5 bits * 7 levels = 35
- bits, but you only use 31 bits in the id). */
-# define TOP_LEVEL_FULL (IDR_FULL >> 30)
#elif BITS_PER_LONG == 64
# define IDR_BITS 6
-# define IDR_FULL 0xfffffffffffffffful
-/* We can only use two of the bits in the top level because there is
- only one possible bit in the top level (6 bits * 6 levels = 36
- bits, but you only use 31 bits in the id). */
-# define TOP_LEVEL_FULL (IDR_FULL >> 62)
#else
# error "BITS_PER_LONG is not 32 or 64"
#endif
@@ -39,7 +29,7 @@
#define IDR_MASK ((1 << IDR_BITS)-1)
struct idr_layer {
- unsigned long bitmap; /* A zero bit means "space here" */
+ DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */
struct idr_layer __rcu *ary[1<<IDR_BITS];
int count; /* When zero, we can release it */
int layer; /* distance from leaf */
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -149,18 +149,18 @@ static void idr_mark_full(struct idr_lay
struct idr_layer *p = pa[0];
int l = 0;
- __set_bit(id & IDR_MASK, &p->bitmap);
+ __set_bit(id & IDR_MASK, p->bitmap);
/*
* If this layer is full mark the bit in the layer above to
* show that this part of the radix tree is full. This may
* complete the layer above and require walking up the radix
* tree.
*/
- while (p->bitmap == IDR_FULL) {
+ while (bitmap_full(p->bitmap, IDR_SIZE)) {
if (!(p = pa[++l]))
break;
id = id >> IDR_BITS;
- __set_bit((id & IDR_MASK), &p->bitmap);
+ __set_bit((id & IDR_MASK), p->bitmap);
}
}
@@ -213,7 +213,6 @@ static int sub_alloc(struct idr *idp, in
int n, m, sh;
struct idr_layer *p, *new;
int l, id, oid;
- unsigned long bm;
id = *starting_id;
restart:
@@ -225,8 +224,7 @@ static int sub_alloc(struct idr *idp, in
* We run around this while until we reach the leaf node...
*/
n = (id >> (IDR_BITS*l)) & IDR_MASK;
- bm = ~p->bitmap;
- m = find_next_bit(&bm, IDR_SIZE, n);
+ m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
if (m == IDR_SIZE) {
/* no space available go back to previous layer. */
l++;
@@ -318,7 +316,8 @@ build_up:
for (new = p; p && p != idp->top; new = p) {
p = p->ary[0];
new->ary[0] = NULL;
- new->bitmap = new->count = 0;
+ new->count = 0;
+ bitmap_clear(new->bitmap, 0, IDR_SIZE);
__move_to_free_list(idp, new);
}
spin_unlock_irqrestore(&idp->lock, flags);
@@ -327,8 +326,8 @@ build_up:
new->ary[0] = p;
new->count = 1;
new->layer = layers-1;
- if (p->bitmap == IDR_FULL)
- __set_bit(0, &new->bitmap);
+ if (bitmap_full(p->bitmap, IDR_SIZE))
+ __set_bit(0, new->bitmap);
p = new;
}
rcu_assign_pointer(idp->top, p);
@@ -506,14 +505,14 @@ static void sub_remove(struct idr *idp,
while ((shift > 0) && p) {
n = (id >> shift) & IDR_MASK;
- __clear_bit(n, &p->bitmap);
+ __clear_bit(n, p->bitmap);
*++paa = &p->ary[n];
p = p->ary[n];
shift -= IDR_BITS;
}
n = id & IDR_MASK;
- if (likely(p != NULL && test_bit(n, &p->bitmap))){
- __clear_bit(n, &p->bitmap);
+ if (likely(p != NULL && test_bit(n, p->bitmap))){
+ __clear_bit(n, p->bitmap);
rcu_assign_pointer(p->ary[n], NULL);
to_free = NULL;
while(*paa && ! --((**paa)->count)){
@@ -556,7 +555,8 @@ void idr_remove(struct idr *idp, int id)
p = idp->top->ary[0];
rcu_assign_pointer(idp->top, p);
--idp->layers;
- to_free->bitmap = to_free->count = 0;
+ to_free->count = 0;
+ bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
free_layer(to_free);
}
while (idp->id_free_cnt >= MAX_IDR_FREE) {
@@ -816,7 +816,7 @@ void *idr_replace(struct idr *idp, void
}
n = id & IDR_MASK;
- if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
+ if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
return ERR_PTR(-ENOENT);
old_p = p->ary[n];
@@ -1013,7 +1013,7 @@ void ida_remove(struct ida *ida, int id)
/* clear full bits while looking up the leaf idr_layer */
while ((shift > 0) && p) {
n = (idr_id >> shift) & IDR_MASK;
- __clear_bit(n, &p->bitmap);
+ __clear_bit(n, p->bitmap);
p = p->ary[n];
shift -= IDR_BITS;
}
@@ -1022,7 +1022,7 @@ void ida_remove(struct ida *ida, int id)
goto err;
n = idr_id & IDR_MASK;
- __clear_bit(n, &p->bitmap);
+ __clear_bit(n, p->bitmap);
bitmap = (void *)p->ary[n];
if (!test_bit(offset, bitmap->bitmap))
@@ -1031,7 +1031,7 @@ void ida_remove(struct ida *ida, int id)
/* update bitmap and remove it if empty */
__clear_bit(offset, bitmap->bitmap);
if (--bitmap->nr_busy == 0) {
- __set_bit(n, &p->bitmap); /* to please idr_remove() */
+ __set_bit(n, p->bitmap); /* to please idr_remove() */
idr_remove(&ida->idr, idr_id);
free_bitmap(ida, bitmap);
}
--
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