[PATCH 02/13]
This patch changes the ridr structures to make them use RCU.
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
---
include/linux/ridr.h | 42 +++++++++++++++++++++++++++---------------
1 file changed, 27 insertions(+), 15 deletions(-)
Index: linux-2.6.25-rc8-mm1/include/linux/ridr.h
===================================================================
--- linux-2.6.25-rc8-mm1.orig/include/linux/ridr.h 2008-04-11 17:17:41.000000000 +0200
+++ linux-2.6.25-rc8-mm1/include/linux/ridr.h 2008-04-11 17:34:35.000000000 +0200
@@ -9,41 +9,53 @@
#define _RIDR_H_
#include <linux/idr.h>
+#include <linux/rcupdate.h>
struct ridr_layer {
unsigned long bitmap; /* A zero bit means "space here" */
struct ridr_layer *ary[1<<IDR_BITS];
int count; /* When zero, we can release it */
+ struct rcu_head rcu_head;
};
struct ridr {
- struct ridr_layer *top;
- struct ridr_layer *id_free;
int layers;
- int id_free_cnt;
- spinlock_t lock;
+ gfp_t gfp_mask;
+ struct ridr_layer *top;
};
-#define RIDR_INIT(name) \
+#define RIDR_INIT(mask) \
{ \
- .top = NULL, \
- .id_free = NULL, \
.layers = 0, \
- .id_free_cnt = 0, \
- .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
+ .gfp_mask = (mask), \
+ .top = NULL, \
}
-#define DEFINE_RIDR(name) struct ridr name = RIDR_INIT(name)
+#define DEFINE_RIDR(name, mask) struct ridr name = RIDR_INIT(mask)
-#define INIT_RIDR(name) \
+#define INIT_RIDR(name, mask) \
do { \
- (name)->top = NULL; \
- (name)->id_free = NULL; \
(name)->layers = 0; \
- (name)->id_free_cnt = 0; \
- (name)->lock = __SPIN_LOCK_UNLOCKED(name.lock); \
+ (name)->gfp_mask = (mask); \
+ (name)->top = NULL; \
} while (0)
+/**
+ * Ridr synchronization (see radix-tree.h)
+ *
+ * ridr_find() is able to be called locklessly, using RCU. The caller must
+ * ensure calls to this function are made within rcu_read_lock() regions.
+ * Other readers (lock-free or otherwise) and modifications may be running
+ * concurrently.
+ *
+ * It is still required that the caller manage the synchronization and
+ * lifetimes of the items. So if RCU lock-free lookups are used, typically
+ * this would mean that the items have their own locks, or are amenable to
+ * lock-free access; and that the items are freed by RCU (or only freed after
+ * having been deleted from the ridr tree *and* a synchronize_rcu() grace
+ * period).
+ */
+
/*
* This is what we export.
*/
--
--
