On Fri, May 11, 2007 at 08:35:27AM +0900, Paul Mundt wrote:
> On Thu, May 10, 2007 at 12:00:08PM -0700, Christoph Lameter wrote:
> > As far as I can tell there is only a single slab destructor left (there
> > is currently another in i386 but its going to go as soon as Andi merges
> > i386s support for quicklists).
> >
> > I wonder how difficult it would be to remove it? If we have no need for
> > destructors anymore then maybe we could remove destructor support from the
> > slab allocators? There is no point in checking for destructor uses in
> > the slab allocators if there are none.
> >
> > Or are there valid reason to keep them around? It seems they were mainly
> > used for list management which required them to take a spinlock. Taking a
> > spinlock in a destructor is a bit risky since the slab allocators may run
> > the destructors anytime they decide a slab is no longer needed.
> >
> > Or do we want to continue support destructors? If so why?
> >
> [snip pmb stuff]
>
> I'll take a look at tidying up the PMB slab, getting rid of the dtor
> shouldn't be terribly painful. I simply opted to do the list management
> there since others were doing it for the PGD slab cache at the time that
> was written.
And here's the bit for dropping pmb_cache_dtor(), moving the list
management up to pmb_alloc() and pmb_free().
With this applied, we're all set for killing off slab destructors
from the kernel entirely.
Signed-off-by: Paul Mundt <[email protected]>
--
arch/sh/mm/pmb.c | 79 ++++++++++++++++++++++++++-----------------------------
1 file changed, 38 insertions(+), 41 deletions(-)
diff --git a/arch/sh/mm/pmb.c b/arch/sh/mm/pmb.c
index 02aae06..b6a5a33 100644
--- a/arch/sh/mm/pmb.c
+++ b/arch/sh/mm/pmb.c
@@ -3,7 +3,7 @@
*
* Privileged Space Mapping Buffer (PMB) Support.
*
- * Copyright (C) 2005, 2006 Paul Mundt
+ * Copyright (C) 2005, 2006, 2007 Paul Mundt
*
* P1/P2 Section mapping definitions from map32.h, which was:
*
@@ -68,6 +68,32 @@ static inline unsigned long mk_pmb_data(unsigned int entry)
return mk_pmb_entry(entry) | PMB_DATA;
}
+static DEFINE_SPINLOCK(pmb_list_lock);
+static struct pmb_entry *pmb_list;
+
+static inline void pmb_list_add(struct pmb_entry *pmbe)
+{
+ struct pmb_entry **p, *tmp;
+
+ p = &pmb_list;
+ while ((tmp = *p) != NULL)
+ p = &tmp->next;
+
+ pmbe->next = tmp;
+ *p = pmbe;
+}
+
+static inline void pmb_list_del(struct pmb_entry *pmbe)
+{
+ struct pmb_entry **p, *tmp;
+
+ for (p = &pmb_list; (tmp = *p); p = &tmp->next)
+ if (tmp == pmbe) {
+ *p = tmp->next;
+ return;
+ }
+}
+
struct pmb_entry *pmb_alloc(unsigned long vpn, unsigned long ppn,
unsigned long flags)
{
@@ -81,11 +107,19 @@ struct pmb_entry *pmb_alloc(unsigned long vpn, unsigned long ppn,
pmbe->ppn = ppn;
pmbe->flags = flags;
+ spin_lock_irq(&pmb_list_lock);
+ pmb_list_add(pmbe);
+ spin_unlock_irq(&pmb_list_lock);
+
return pmbe;
}
void pmb_free(struct pmb_entry *pmbe)
{
+ spin_lock_irq(&pmb_list_lock);
+ pmb_list_del(pmbe);
+ spin_unlock_irq(&pmb_list_lock);
+
kmem_cache_free(pmb_cache, pmbe);
}
@@ -167,31 +201,6 @@ void clear_pmb_entry(struct pmb_entry *pmbe)
clear_bit(entry, &pmb_map);
}
-static DEFINE_SPINLOCK(pmb_list_lock);
-static struct pmb_entry *pmb_list;
-
-static inline void pmb_list_add(struct pmb_entry *pmbe)
-{
- struct pmb_entry **p, *tmp;
-
- p = &pmb_list;
- while ((tmp = *p) != NULL)
- p = &tmp->next;
-
- pmbe->next = tmp;
- *p = pmbe;
-}
-
-static inline void pmb_list_del(struct pmb_entry *pmbe)
-{
- struct pmb_entry **p, *tmp;
-
- for (p = &pmb_list; (tmp = *p); p = &tmp->next)
- if (tmp == pmbe) {
- *p = tmp->next;
- return;
- }
-}
static struct {
unsigned long size;
@@ -283,25 +292,14 @@ void pmb_unmap(unsigned long addr)
} while (pmbe);
}
-static void pmb_cache_ctor(void *pmb, struct kmem_cache *cachep, unsigned long flags)
+static void pmb_cache_ctor(void *pmb, struct kmem_cache *cachep,
+ unsigned long flags)
{
struct pmb_entry *pmbe = pmb;
memset(pmb, 0, sizeof(struct pmb_entry));
- spin_lock_irq(&pmb_list_lock);
-
pmbe->entry = PMB_NO_ENTRY;
- pmb_list_add(pmbe);
-
- spin_unlock_irq(&pmb_list_lock);
-}
-
-static void pmb_cache_dtor(void *pmb, struct kmem_cache *cachep, unsigned long flags)
-{
- spin_lock_irq(&pmb_list_lock);
- pmb_list_del(pmb);
- spin_unlock_irq(&pmb_list_lock);
}
static int __init pmb_init(void)
@@ -312,8 +310,7 @@ static int __init pmb_init(void)
BUG_ON(unlikely(nr_entries >= NR_PMB_ENTRIES));
pmb_cache = kmem_cache_create("pmb", sizeof(struct pmb_entry), 0,
- SLAB_PANIC, pmb_cache_ctor,
- pmb_cache_dtor);
+ SLAB_PANIC, pmb_cache_ctor, NULL);
jump_to_P2();
-
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