Messages in this thread Patch in this message | | | Date | Fri, 11 Apr 2008 18:17:04 +0200 | From | Nadia.Derbey@bull ... | Subject | [PATCH 02/13] Change ridr structure |
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[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. */ --
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