The patch titled
idr: introduce ridr_find()
has been added to the -mm tree. Its filename is
idr-introduce-ridr_find.patch
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------------------------------------------------------
Subject: idr: introduce ridr_find()
From: Nadia Derbey <Nadia.Derbey@xxxxxxxx>
Introduce the ridr_find() routine.
Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx>
Cc: Jim Houston <jim.houston@xxxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Cc: Pierre Peiffer <peifferp@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ridr.h | 17 +++++++++++++++++
lib/ridr.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff -puN include/linux/ridr.h~idr-introduce-ridr_find include/linux/ridr.h
--- a/include/linux/ridr.h~idr-introduce-ridr_find
+++ a/include/linux/ridr.h
@@ -40,9 +40,26 @@ struct ridr {
#define idr_to_ridr(p) container_of((p), struct ridr_layer, idr)
#define ridr_to_idr(p) (&((p)->idr))
+/**
+ * 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.
*/
+void *ridr_find(struct ridr *, int);
int ridr_pre_get(struct ridr *, gfp_t);
int ridr_get_new(struct ridr *, void *, int *);
int ridr_get_new_above(struct ridr *, void *, int, int *);
diff -puN lib/ridr.c~idr-introduce-ridr_find lib/ridr.c
--- a/lib/ridr.c~idr-introduce-ridr_find
+++ a/lib/ridr.c
@@ -259,6 +259,40 @@ int ridr_get_new(struct ridr *idp, void
}
EXPORT_SYMBOL(ridr_get_new);
+/**
+ * ridr_find - return pointer for given id
+ * @idp: ridr handle
+ * @id: lookup key
+ *
+ * Return the pointer given the id it has been registered with. A %NULL
+ * return indicates that @id is not valid or you passed %NULL in
+ * ridr_get_new().
+ *
+ * This function can be called under rcu_read_lock(), given that the leaf
+ * pointers lifetimes are correctly managed.
+ */
+void *ridr_find(struct ridr *idp, int id)
+{
+ int n;
+ struct ridr_layer *p;
+
+ n = idp->layers * IDR_BITS;
+ p = rcu_dereference(idp->top);
+
+ /* Mask off upper bits we don't use for the search. */
+ id &= MAX_ID_MASK;
+
+ if (id >= (1 << n))
+ return NULL;
+
+ while (n > 0 && p) {
+ n -= IDR_BITS;
+ p = rcu_dereference(p->idr.ary[(id >> n) & IDR_MASK]);
+ }
+ return((void *)p);
+}
+EXPORT_SYMBOL(ridr_find);
+
static void ridr_cache_ctor(struct kmem_cache *ridr_layer_cache,
void *ridr_layer)
{
_
Patches currently in -mm which might be from Nadia.Derbey@xxxxxxxx are
ipc-use-ipc_buildid-directly-from-ipc_addid.patch
ipc-scale-msgmni-to-the-amount-of-lowmem.patch
ipc-scale-msgmni-to-the-number-of-ipc-namespaces.patch
ipc-define-the-slab_memory_callback-priority-as-a-constant.patch
ipc-recompute-msgmni-on-memory-add--remove.patch
ipc-invoke-the-ipcns-notifier-chain-as-a-work-item.patch
ipc-recompute-msgmni-on-ipc-namespace-creation-removal.patch
ipc-do-not-recompute-msgmni-anymore-if-explicitly-set-by-user.patch
ipc-re-enable-msgmni-automatic-recomputing-msgmni-if-set-to-negative.patch
ipc-semaphores-code-factorisation.patch
ipc-shared-memory-introduce-shmctl_down.patch
ipc-message-queues-introduce-msgctl_down.patch
ipc-semaphores-move-the-rwmutex-handling-inside-semctl_down.patch
ipc-semaphores-remove-one-unused-parameter-from-semctl_down.patch
ipc-get-rid-of-the-use-_setbuf-structure.patch
ipc-introduce-ipc_update_perm.patch
ipc-consolidate-all-xxxctl_down-functions.patch
ipc-add-definitions-of-ushort_max-and-others.patch
proc-introduce-proc_create_data-to-setup-de-data.patch
sysvipc-use-non-racy-method-for-proc-entries-creation.patch
idr-fix-idr_remove.patch
idr-introduce-the-ridr-structure.patch
idr-introduce-ridr_pre_get.patch
idr-introduce-ridr_init.patch
idr-introduce-ridr_get_new_above.patch
idr-introduce-ridr_get_new.patch
idr-introduce-ridr_find.patch
idr-introduce-ridr_remove.patch
ipc-integrate-the-ridr-code-into-ipc-code.patch
ipc-get-rid-of-ipc_lock_down.patch
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