Cleanup kmem_cache_create()
mcd@arrakis:~/linux/source/linux-2.6.14+slab_cleanup/patches $ diffstat
kmem_cache_create.patch
slab.c | 69
++++++++++++++++++++++++++++-------------------------------------
1 files changed, 30 insertions(+), 39 deletions(-)
-Matt
General readability fixes.
* Reformat a looong if statement
* Replace a constant (4096) with what it represents (PAGE_SIZE)
* Replace a confusing label (opps) with a more sensible one (out)
* Refactor a do {} while loop w/ a couple labels and gotos into
a for loop with breaks and continues.
* Rewrite some confusing slab alignment code for readability
* Replace a list_for_each/list_entry combo with an identical but
more readable list_for_each_entry loop.
Index: linux-2.6.14+slab_cleanup/mm/slab.c
===================================================================
--- linux-2.6.14+slab_cleanup.orig/mm/slab.c 2005-11-07 15:58:48.547771048 -0800
+++ linux-2.6.14+slab_cleanup/mm/slab.c 2005-11-07 15:58:50.495474952 -0800
@@ -1499,21 +1499,18 @@ kmem_cache_t *kmem_cache_create(const ch
void (*ctor)(void *, kmem_cache_t *, unsigned long),
void (*dtor)(void *, kmem_cache_t *, unsigned long))
{
- size_t left_over, slab_size, ralign;
+ size_t left_over, slab_size, aligned_slab_size, ralign;
kmem_cache_t *cachep = NULL;
/*
* Sanity checks... these are all serious usage bugs.
*/
- if ((!name) ||
- in_interrupt() ||
- (size < BYTES_PER_WORD) ||
- (size > (1<<MAX_OBJ_ORDER)*PAGE_SIZE) ||
- (dtor && !ctor)) {
- printk(KERN_ERR "%s: Early error in slab %s\n",
- __FUNCTION__, name);
- BUG();
- }
+ if (!name || in_interrupt() || (size < BYTES_PER_WORD) ||
+ (size > (1 << MAX_OBJ_ORDER) * PAGE_SIZE) || (dtor && !ctor)) {
+ printk(KERN_ERR "%s: Early error in slab %s\n",
+ __FUNCTION__, name);
+ BUG();
+ }
#if DEBUG
WARN_ON(strchr(name, ' ')); /* It confuses parsers */
@@ -1531,7 +1528,7 @@ kmem_cache_t *kmem_cache_create(const ch
* above the next power of two: caches with object sizes just above a
* power of two have a significant amount of internal fragmentation.
*/
- if ((size < 4096 || fls(size-1) == fls(size-1+3*BYTES_PER_WORD)))
+ if (size < PAGE_SIZE || fls(size-1) == fls(size-1 + 3*BYTES_PER_WORD))
flags |= SLAB_RED_ZONE|SLAB_STORE_USER;
if (!(flags & SLAB_DESTROY_BY_RCU))
flags |= SLAB_POISON;
@@ -1594,7 +1591,7 @@ kmem_cache_t *kmem_cache_create(const ch
/* Get cache's description obj. */
cachep = (kmem_cache_t *) kmem_cache_alloc(&cache_cache, SLAB_KERNEL);
if (!cachep)
- goto opps;
+ goto out;
memset(cachep, 0, sizeof(kmem_cache_t));
#if DEBUG
@@ -1652,9 +1649,9 @@ kmem_cache_t *kmem_cache_create(const ch
* gfp() funcs are more friendly towards high-order requests,
* this should be changed.
*/
- do {
- unsigned int break_flag = 0;
-cal_wastage:
+ unsigned int break_flag = 0;
+
+ for ( ; ; cachep->gfporder++) {
cache_estimate(cachep->gfporder, size, align, flags,
&left_over, &cachep->num);
if (break_flag)
@@ -1662,13 +1659,13 @@ cal_wastage:
if (cachep->gfporder >= MAX_GFP_ORDER)
break;
if (!cachep->num)
- goto next;
- if (flags & CFLGS_OFF_SLAB &&
- cachep->num > offslab_limit) {
+ continue;
+ if ((flags & CFLGS_OFF_SLAB) &&
+ (cachep->num > offslab_limit)) {
/* This num of objs will cause problems. */
- cachep->gfporder--;
+ cachep->gfporder -= 2;
break_flag++;
- goto cal_wastage;
+ continue;
}
/*
@@ -1680,33 +1677,29 @@ cal_wastage:
if ((left_over*8) <= (PAGE_SIZE<<cachep->gfporder))
break; /* Acceptable internal fragmentation. */
-next:
- cachep->gfporder++;
- } while (1);
+ }
}
if (!cachep->num) {
printk("kmem_cache_create: couldn't create cache %s.\n", name);
kmem_cache_free(&cache_cache, cachep);
cachep = NULL;
- goto opps;
+ goto out;
}
- slab_size = ALIGN(cachep->num*sizeof(kmem_bufctl_t)
- + sizeof(struct slab), align);
+ slab_size = cachep->num * sizeof(kmem_bufctl_t) + sizeof(struct slab);
+ aligned_slab_size = ALIGN(slab_size, align);
/*
* If the slab has been placed off-slab, and we have enough space then
* move it on-slab. This is at the expense of any extra colouring.
*/
- if (flags & CFLGS_OFF_SLAB && left_over >= slab_size) {
+ if (flags & CFLGS_OFF_SLAB && left_over >= aligned_slab_size) {
flags &= ~CFLGS_OFF_SLAB;
- left_over -= slab_size;
- }
-
- if (flags & CFLGS_OFF_SLAB) {
- /* really off slab. No need for manual alignment */
- slab_size = cachep->num*sizeof(kmem_bufctl_t)+sizeof(struct slab);
+ left_over -= aligned_slab_size;
}
+ /* On slab, need manual alignment */
+ if (!(flags & CFLGS_OFF_SLAB))
+ slab_size = aligned_slab_size;
cachep->colour_off = cache_line_size();
/* Offset must be a multiple of the alignment. */
@@ -1789,13 +1782,12 @@ next:
/* Need the semaphore to access the chain. */
down(&cache_chain_sem);
{
- struct list_head *p;
+ kmem_cache_t *pc;
mm_segment_t old_fs;
old_fs = get_fs();
set_fs(KERNEL_DS);
- list_for_each(p, &cache_chain) {
- kmem_cache_t *pc = list_entry(p, kmem_cache_t, next);
+ list_for_each_entry(pc, &cache_chain, next) {
char tmp;
/*
* This happens when the module gets unloaded & doesn't
@@ -1821,10 +1813,9 @@ next:
list_add(&cachep->next, &cache_chain);
up(&cache_chain_sem);
unlock_cpu_hotplug();
-opps:
+out:
if (!cachep && (flags & SLAB_PANIC))
- panic("kmem_cache_create(): failed to create slab `%s'\n",
- name);
+ panic("%s: failed to create slab `%s'\n", __FUNCTION__, name);
return cachep;
}
EXPORT_SYMBOL(kmem_cache_create);
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