From: Nadia.Derbey@bull.net
To: manfred@colorfullife.com, paulmck@linux.vnet.ibm.com,
lnxninja@linux.vnet.ibm.com
Cc: linux-kernel@vger.kernel.org, efault@gmx.de,
akpm@linux-foundation.org, Nadia Derbey <Nadia.Derbey@bull.net>
Subject: [PATCH 7/9] Make idr_remove rcu-safe
Date: Wed, 07 May 2008 13:36:00 +0200 [thread overview]
Message-ID: <20080507113737.562143000@bull.net> (raw)
In-Reply-To: 20080507113553.395937000@bull.net
[-- Attachment #1: idr_remove_rcu_safe.patch --]
[-- Type: text/plain, Size: 3990 bytes --]
[PATCH 07/09]
This patch introduces the free_layer() routine: it is the one that actually
frees memory after a grace period has elapsed.
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
---
lib/idr.c | 59 ++++++++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 44 insertions(+), 15 deletions(-)
Index: linux-2.6.25-mm1/lib/idr.c
===================================================================
--- linux-2.6.25-mm1.orig/lib/idr.c 2008-05-06 18:06:43.000000000 +0200
+++ linux-2.6.25-mm1/lib/idr.c 2008-05-07 09:07:31.000000000 +0200
@@ -52,6 +52,19 @@ static struct idr_layer *get_from_free_l
return(p);
}
+static void idr_layer_rcu_free(struct rcu_head *head)
+{
+ struct idr_layer *layer;
+
+ layer = container_of(head, struct idr_layer, rcu_head);
+ kmem_cache_free(idr_layer_cache, layer);
+}
+
+static inline void free_layer(struct idr_layer *p)
+{
+ call_rcu(&p->rcu_head, idr_layer_rcu_free);
+}
+
/* only called when idp->lock is held */
static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
{
@@ -334,6 +347,7 @@ static void sub_remove(struct idr *idp,
struct idr_layer *p = idp->top;
struct idr_layer **pa[MAX_LEVEL];
struct idr_layer ***paa = &pa[0];
+ struct idr_layer *to_free;
int n;
*paa = NULL;
@@ -349,13 +363,18 @@ static void sub_remove(struct idr *idp,
n = id & IDR_MASK;
if (likely(p != NULL && test_bit(n, &p->bitmap))){
__clear_bit(n, &p->bitmap);
- p->ary[n] = NULL;
+ rcu_assign_pointer(p->ary[n], NULL);
+ to_free = NULL;
while(*paa && ! --((**paa)->count)){
- move_to_free_list(idp, **paa);
+ if (to_free)
+ free_layer(to_free);
+ to_free = **paa;
**paa-- = NULL;
}
if (!*paa)
idp->layers = 0;
+ if (to_free)
+ free_layer(to_free);
} else
idr_remove_warning(id);
}
@@ -368,25 +387,37 @@ static void sub_remove(struct idr *idp,
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_ID_MASK;
sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
- idp->top->ary[0]) { // We can drop a layer
-
+ idp->top->ary[0]) {
+ /*
+ * Single child at leftmost slot: we can shrink the tree.
+ * This level is not needed anymore since when layers are
+ * inserted, they are inserted at the top of the existing
+ * tree.
+ */
+ to_free = idp->top;
p = idp->top->ary[0];
- idp->top->bitmap = idp->top->count = 0;
- move_to_free_list(idp, idp->top);
- idp->top = p;
+ rcu_assign_pointer(idp->top, p);
--idp->layers;
+ to_free->bitmap = to_free->count = 0;
+ free_layer(to_free);
}
while (idp->id_free_cnt >= IDR_FREE_MAX) {
p = get_from_free_list(idp);
+ /*
+ * Note: we don't call the rcu callback here, since the only
+ * layers that fall into the freelist are those that have been
+ * preallocated.
+ */
kmem_cache_free(idr_layer_cache, p);
- return;
}
+ return;
}
EXPORT_SYMBOL(idr_remove);
@@ -424,15 +455,13 @@ void idr_remove_all(struct idr *idp)
id += 1 << n;
while (n < fls(id)) {
- if (p) {
- memset(p, 0, sizeof *p);
- move_to_free_list(idp, p);
- }
+ if (p)
+ free_layer(p);
n += IDR_BITS;
p = *--paa;
}
}
- idp->top = NULL;
+ rcu_assign_pointer(idp->top, NULL);
idp->layers = 0;
}
EXPORT_SYMBOL(idr_remove_all);
@@ -549,7 +578,7 @@ EXPORT_SYMBOL(idr_for_each);
* A -ENOENT return indicates that @id was not found.
* A -EINVAL return indicates that @id was not within valid constraints.
*
- * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove().
+ * The caller must serialize with writers.
*/
void *idr_replace(struct idr *idp, void *ptr, int id)
{
@@ -575,7 +604,7 @@ void *idr_replace(struct idr *idp, void
return ERR_PTR(-ENOENT);
old_p = p->ary[n];
- p->ary[n] = ptr;
+ rcu_assign_pointer(p->ary[n], ptr);
return old_p;
}
--
next prev parent reply other threads:[~2008-05-07 11:40 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-07 11:35 [PATCH 0/9] Scalability requirements for sysv ipc - v3 Nadia.Derbey
2008-05-07 11:35 ` [PATCH 1/9] Change the idr structure Nadia.Derbey
2008-05-08 17:12 ` Rik van Riel
2008-05-30 8:22 ` Paul E. McKenney
2008-05-07 11:35 ` [PATCH 2/9] Rename some of the idr APIs internal routines Nadia.Derbey
2008-05-08 17:15 ` Rik van Riel
2008-05-30 8:23 ` Paul E. McKenney
2008-05-07 11:35 ` [PATCH 3/9] Fix a printk call Nadia.Derbey
2008-05-08 17:43 ` Rik van Riel
2008-05-30 8:23 ` Paul E. McKenney
2008-05-07 11:35 ` [PATCH 4/9] Error checking factorization Nadia.Derbey
2008-05-08 17:45 ` Rik van Riel
2008-05-07 11:35 ` [PATCH 5/9] Make idr_get_new* rcu-safe Nadia.Derbey
2008-05-08 17:55 ` Rik van Riel
2008-05-30 8:23 ` Paul E. McKenney
2008-05-07 11:35 ` [PATCH 6/9] Make idr_find rcu-safe Nadia.Derbey
2008-05-08 17:58 ` Rik van Riel
2008-05-30 8:24 ` Paul E. McKenney
2008-05-07 11:36 ` Nadia.Derbey [this message]
2008-05-08 18:02 ` [PATCH 7/9] Make idr_remove rcu-safe Rik van Riel
2008-05-14 19:59 ` Tim Pepper
2008-05-15 7:40 ` Nadia Derbey
2008-05-20 5:29 ` Tim Pepper
2008-05-20 5:35 ` Tim Pepper
2008-05-20 7:03 ` Nadia Derbey
2008-05-20 16:26 ` Tim Pepper
2008-05-30 8:24 ` Paul E. McKenney
2008-05-07 11:36 ` [PATCH 8/9] Call idr_find() without locking in ipc_lock() Nadia.Derbey
2008-05-08 18:11 ` Rik van Riel
2008-05-30 8:27 ` Paul E. McKenney
2008-05-07 11:36 ` [PATCH 9/9] Get rid of ipc_lock_down() Nadia.Derbey
2008-05-08 18:13 ` Rik van Riel
2008-05-30 8:29 ` Paul E. McKenney
2008-05-07 11:41 ` [PATCH 0/9] Scalability requirements for sysv ipc - v3 Nadia Derbey
2008-05-07 13:19 ` KOSAKI Motohiro
2008-05-13 14:10 ` Nadia Derbey
2008-05-14 4:22 ` KOSAKI Motohiro
2008-05-30 8:22 ` Paul E. McKenney
2008-06-02 5:53 ` Nadia Derbey
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