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Message-Id: <1373087301-23730-9-git-send-email-kmo@daterainc.com>
Date: Fri, 5 Jul 2013 22:08:19 -0700
From: Kent Overstreet <kmo@...erainc.com>
To: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Cc: tj@...nel.org, sfr@...b.auug.org.au, andi@...stfloor.org,
oleg@...hat.com, mingo@...hat.com, nab@...ux-iscsi.org,
axboe@...nel.dk, Kent Overstreet <kmo@...erainc.com>,
Kent Overstreet <koverstreet@...gle.com>
Subject: [PATCH 08/10] idr: Reimplement idr on top of ida/radix trees
The old idr code was really a second radix tree implementation - we
already have one in lib/radix-tree.c.
This patch reimplements idr on top of our existing radix trees, using
our shiny new ida implementation for allocating/freeing the ids. The old
idr code was noticably slower than lib/radix-tree.c in at least some
benchmarks, so in addition to being ~500 lines less code this patch
should improve performance too.
There's one thing left unfinished in this patch - the existing
idr_preload() interface won't work for ida. Another patch on top of this
will fix idr_preload() and update existing users to the new interface.
Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Tejun Heo <tj@...nel.org>
Signed-off-by: Kent Overstreet <kmo@...erainc.com>
---
include/linux/idr.h | 157 ++++-----
init/main.c | 1 -
lib/idr.c | 896 ++++++++++------------------------------------------
3 files changed, 249 insertions(+), 805 deletions(-)
diff --git a/include/linux/idr.h b/include/linux/idr.h
index 6fc0225..85355d7 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -1,6 +1,6 @@
/*
* include/linux/idr.h
- *
+ *
* 2002-10-18 written by Jim Houston jim.houston@...r.com
* Copyright (C) 2002 by Concurrent Computer Corporation
* Distributed under the GNU GPL license version 2.
@@ -12,10 +12,8 @@
#ifndef __IDR_H__
#define __IDR_H__
-#include <linux/types.h>
-#include <linux/bitops.h>
-#include <linux/init.h>
-#include <linux/rcupdate.h>
+#include <linux/gfp.h>
+#include <linux/radix-tree.h>
#include <linux/spinlock_types.h>
#include <linux/wait.h>
@@ -149,74 +147,42 @@ int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags);
/* IDR */
-/*
- * We want shallower trees and thus more bits covered at each layer. 8
- * bits gives us large enough first layer for most use cases and maximum
- * tree depth of 4. Each idr_layer is slightly larger than 2k on 64bit and
- * 1k on 32bit.
+/**
+ * DOC: idr sync
+ * idr synchronization (stolen from radix-tree.h)
+ *
+ * idr_alloc() and idr_remove() do their own locking internally - the user need
+ * not be concerned with synchronization unless there's other operations that
+ * need to be done atomically.
+ *
+ * idr_find() does no locking - it can be called locklessly using RCU, if the
+ * caller ensures calls to this function are made within rcu_read_lock()
+ * regions and does all the other appropriate RCU stuff.
*/
-#define IDR_BITS 8
-#define IDR_SIZE (1 << IDR_BITS)
-#define IDR_MASK ((1 << IDR_BITS)-1)
-
-struct idr_layer {
- int prefix; /* the ID prefix of this idr_layer */
- DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */
- struct idr_layer __rcu *ary[1<<IDR_BITS];
- int count; /* When zero, we can release it */
- int layer; /* distance from leaf */
- struct rcu_head rcu_head;
-};
struct idr {
- struct idr_layer __rcu *hint; /* the last layer allocated from */
- struct idr_layer __rcu *top;
- struct idr_layer *id_free;
- int layers; /* only valid w/o concurrent changes */
- int id_free_cnt;
- int cur; /* current pos for cyclic allocation */
- spinlock_t lock;
+ struct ida ida;
+ struct radix_tree_root ptrs;
};
#define IDR_INIT(name) \
{ \
- .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
+ .ida = IDA_INIT(name.ida), \
+ .ptrs = RADIX_TREE_INIT(GFP_NOWAIT), \
}
#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
-/**
- * DOC: idr sync
- * idr synchronization (stolen from radix-tree.h)
- *
- * idr_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 idr tree *and* a synchronize_rcu() grace
- * period).
- */
-
-/*
- * This is what we export.
- */
-
-void *idr_find_slowpath(struct idr *idp, int id);
-void idr_preload(gfp_t gfp_mask);
-int idr_alloc_range(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask);
-int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask);
-int idr_for_each(struct idr *idp,
+void *idr_find_next(struct idr *idr, int *nextid);
+int idr_for_each(struct idr *idr,
int (*fn)(int id, void *p, void *data), void *data);
-void *idr_find_next(struct idr *idp, int *nextid);
-void *idr_replace(struct idr *idp, void *ptr, int id);
-void idr_remove(struct idr *idp, int id);
-void idr_free(struct idr *idp, int id);
-void idr_destroy(struct idr *idp);
-void idr_init(struct idr *idp);
+void *idr_replace(struct idr *idr, void *ptr, unsigned id);
+void idr_remove(struct idr *idr, unsigned id);
+int idr_alloc_range(struct idr *idr, void *ptr, unsigned start,
+ unsigned end, gfp_t gfp);
+int idr_alloc_cyclic(struct idr *idr, void *ptr, unsigned start,
+ unsigned end, gfp_t gfp_mask);
+void idr_destroy(struct idr *idr);
+void idr_init(struct idr *idr);
static inline int idr_alloc(struct idr *idr, void *ptr, gfp_t gfp)
{
@@ -231,7 +197,53 @@ static inline int idr_alloc(struct idr *idr, void *ptr, gfp_t gfp)
*/
static inline void idr_preload_end(void)
{
- preempt_enable();
+ radix_tree_preload_end();
+}
+
+/**
+ * idr_preload - preload for idr_alloc_range()
+ * @gfp: allocation mask to use for preloading
+ *
+ * Preload per-cpu layer buffer for idr_alloc_range(). Can only be used from
+ * process context and each idr_preload() invocation should be matched with
+ * idr_preload_end(). Note that preemption is disabled while preloaded.
+ *
+ * The first idr_alloc_range() in the preloaded section can be treated as if it
+ * were invoked with @gfp_mask used for preloading. This allows using more
+ * permissive allocation masks for idrs protected by spinlocks.
+ *
+ * For example, if idr_alloc_range() below fails, the failure can be treated as
+ * if idr_alloc_range() were called with GFP_KERNEL rather than GFP_NOWAIT.
+ *
+ * idr_preload(GFP_KERNEL);
+ * spin_lock(lock);
+ *
+ * id = idr_alloc_range(idr, ptr, start, end, GFP_NOWAIT);
+ *
+ * spin_unlock(lock);
+ * idr_preload_end();
+ * if (id < 0)
+ * error;
+ */
+static inline void idr_preload(gfp_t gfp)
+{
+ might_sleep_if(gfp & __GFP_WAIT);
+
+ /* Well this is horrible, but idr_preload doesn't return errors */
+ if (radix_tree_preload(gfp))
+ preempt_disable();
+}
+
+/* radix tree can't store NULL pointers, so we have to translate... */
+static inline void *__radix_idr_ptr(void *ptr)
+{
+ return ptr != (void *) (~0UL & ~RADIX_TREE_INDIRECT_PTR)
+ ? ptr : NULL;
+}
+
+static inline void *__idr_radix_ptr(void *ptr)
+{
+ return ptr ?: (void *) (~0UL & ~RADIX_TREE_INDIRECT_PTR);
}
/**
@@ -241,24 +253,19 @@ static inline void idr_preload_end(void)
*
* 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
- * idr_get_new().
+ * idr_alloc().
*
* This function can be called under rcu_read_lock(), given that the leaf
* pointers lifetimes are correctly managed.
*/
-static inline void *idr_find(struct idr *idr, int id)
+static inline void *idr_find(struct idr *idr, unsigned id)
{
- struct idr_layer *hint = rcu_dereference_raw(idr->hint);
-
- if (hint && (id & ~IDR_MASK) == hint->prefix)
- return rcu_dereference_raw(hint->ary[id & IDR_MASK]);
-
- return idr_find_slowpath(idr, id);
+ return __radix_idr_ptr(radix_tree_lookup(&idr->ptrs, id));
}
/**
* idr_for_each_entry - iterate over an idr's elements of a given type
- * @idp: idr handle
+ * @idr: idr handle
* @entry: the type * to use as cursor
* @id: id entry's key
*
@@ -266,9 +273,7 @@ static inline void *idr_find(struct idr *idr, int id)
* after normal terminatinon @entry is left with the value NULL. This
* is convenient for a "not found" value.
*/
-#define idr_for_each_entry(idp, entry, id) \
- for (id = 0; ((entry) = idr_find_next(idp, &(id))) != NULL; ++id)
-
-void __init idr_init_cache(void);
+#define idr_for_each_entry(idr, entry, id) \
+ for (id = 0; ((entry) = idr_find_next(idr, &(id))) != NULL; ++id)
#endif /* __IDR_H__ */
diff --git a/init/main.c b/init/main.c
index 9484f4b..87b5a0f 100644
--- a/init/main.c
+++ b/init/main.c
@@ -541,7 +541,6 @@ asmlinkage void __init start_kernel(void)
preempt_disable();
if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
local_irq_disable();
- idr_init_cache();
perf_event_init();
rcu_init();
tick_nohz_init();
diff --git a/lib/idr.c b/lib/idr.c
index a3977aa..fc7cb1a 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -8,24 +8,10 @@
*
* Modified by Nadia Derbey to make it RCU safe.
*
- * IDA completely rewritten by Kent Overstreet <koverstreet@...gle.com>
+ * Completely rewritten by Kent Overstreet <koverstreet@...gle.com>.
*
- * Small id to pointer translation service.
- *
- * It uses a radix tree like structure as a sparse array indexed
- * by the id to obtain the pointer. The bitmap makes allocating
- * a new id quick.
- *
- * You call it to allocate an id (an int) an associate with that id a
- * pointer or what ever, we treat it as a (void *). You can pass this
- * id to a user for him to pass back at a later time. You then pass
- * that id to this code and it returns your pointer.
-
- * You can release ids at any time. When all ids are released, most of
- * the memory is returned (we keep MAX_IDR_FREE) in a local pool so we
- * don't need to go to the memory "store" during an id allocate, just
- * so you don't need to be too concerned about locking and conflicts
- * with the slab allocator.
+ * id allocator (scalable/resizable bitmap, essentially), and also idr which
+ * combines ida with a radix tree to map pointers to small integers for you.
*/
#include <linux/bitmap.h>
@@ -33,11 +19,10 @@
#include <linux/bug.h>
#include <linux/err.h>
#include <linux/export.h>
-#include <linux/hardirq.h>
#include <linux/idr.h>
-#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/percpu.h>
+#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
@@ -911,389 +896,158 @@ err:
}
EXPORT_SYMBOL_GPL(percpu_ida_init);
-/* IDR */
-
-#define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
-#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
-
-/* Leave the possibility of an incomplete final layer */
-#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
-
-/* Number of id_layer structs to leave in free list */
-#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
-
-static struct kmem_cache *idr_layer_cache;
-static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head);
-static DEFINE_PER_CPU(int, idr_preload_cnt);
-
-/* the maximum ID which can be allocated given idr->layers */
-static int idr_max(int layers)
-{
- int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
-
- return (1 << bits) - 1;
-}
-
-/*
- * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
- * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
- * so on.
+/**
+ * DOC: IDR description
+ * IDR: Maps ids (small integers) to pointers.
+ *
+ * This merely combines ida (id allocation) with a radix tree; idr_alloc()
+ * stores a pointer, and returns you a small integer by which you can refer to
+ * it.
+ *
+ * It'll give you the smallest available integer (within a specified range if
+ * you use idr_alloc_range()) - there's also idr_alloc_cyclic() if you don't
+ * want ids to be reused right away.
+ *
+ * id -> pointer mappings can be deleted with idr_remove().
*/
-static int idr_layer_prefix_mask(int layer)
-{
- return ~idr_max(layer + 1);
-}
-
-static struct idr_layer *get_from_free_list(struct idr *idp)
-{
- struct idr_layer *p;
- unsigned long flags;
-
- spin_lock_irqsave(&idp->lock, flags);
- if ((p = idp->id_free)) {
- idp->id_free = p->ary[0];
- idp->id_free_cnt--;
- p->ary[0] = NULL;
- }
- spin_unlock_irqrestore(&idp->lock, flags);
- return(p);
-}
/**
- * idr_layer_alloc - allocate a new idr_layer
- * @gfp_mask: allocation mask
- * @layer_idr: optional idr to allocate from
+ * idr_find_next - lookup next object of id to given id.
+ * @idr: idr handle
+ * @nextidp: pointer to lookup key
*
- * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
- * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
- * an idr_layer from @idr->id_free.
+ * Returns pointer to registered object with id, which is next number to
+ * given id. After being looked up, *@...tidp will be updated for the next
+ * iteration.
*
- * @layer_idr is to maintain backward compatibility with the old alloc
- * interface - idr_pre_get() and idr_get_new*() - and will be removed
- * together with per-pool preload buffer.
+ * This function can be called under rcu_read_lock(), given that the leaf
+ * pointers lifetimes are correctly managed.
*/
-static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr)
-{
- struct idr_layer *new;
-
- /* this is the old path, bypass to get_from_free_list() */
- if (layer_idr)
- return get_from_free_list(layer_idr);
-
- /*
- * Try to allocate directly from kmem_cache. We want to try this
- * before preload buffer; otherwise, non-preloading idr_alloc_range()
- * users will end up taking advantage of preloading ones. As the
- * following is allowed to fail for preloaded cases, suppress
- * warning this time.
- */
- new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN);
- if (new)
- return new;
-
- /*
- * Try to fetch one from the per-cpu preload buffer if in process
- * context. See idr_preload() for details.
- */
- if (!in_interrupt()) {
- preempt_disable();
- new = __this_cpu_read(idr_preload_head);
- if (new) {
- __this_cpu_write(idr_preload_head, new->ary[0]);
- __this_cpu_dec(idr_preload_cnt);
- new->ary[0] = NULL;
- }
- preempt_enable();
- if (new)
- return new;
- }
-
- /*
- * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
- * that memory allocation failure warning is printed as intended.
- */
- return kmem_cache_zalloc(idr_layer_cache, gfp_mask);
-}
-
-static void idr_layer_rcu_free(struct rcu_head *head)
+void *idr_find_next(struct idr *idr, int *nextidp)
{
- struct idr_layer *layer;
+ void **slot;
+ struct radix_tree_iter iter;
+ void *ret = NULL;
- layer = container_of(head, struct idr_layer, rcu_head);
- kmem_cache_free(idr_layer_cache, layer);
-}
+ rcu_read_lock();
-static inline void free_layer(struct idr *idr, struct idr_layer *p)
-{
- if (idr->hint && idr->hint == p)
- RCU_INIT_POINTER(idr->hint, NULL);
- 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)
-{
- p->ary[0] = idp->id_free;
- idp->id_free = p;
- idp->id_free_cnt++;
-}
+ radix_tree_for_each_slot(slot, &idr->ptrs, &iter, *nextidp) {
+ *nextidp = iter.index;
+ ret = radix_tree_deref_slot(slot);
+ break;
+ }
-static void move_to_free_list(struct idr *idp, struct idr_layer *p)
-{
- unsigned long flags;
+ rcu_read_unlock();
- /*
- * Depends on the return element being zeroed.
- */
- spin_lock_irqsave(&idp->lock, flags);
- __move_to_free_list(idp, p);
- spin_unlock_irqrestore(&idp->lock, flags);
-}
-
-static void idr_mark_full(struct idr_layer **pa, int id)
-{
- struct idr_layer *p = pa[0];
- int l = 0;
-
- __set_bit(id & IDR_MASK, p->bitmap);
- /*
- * If this layer is full mark the bit in the layer above to
- * show that this part of the radix tree is full. This may
- * complete the layer above and require walking up the radix
- * tree.
- */
- while (bitmap_full(p->bitmap, IDR_SIZE)) {
- if (!(p = pa[++l]))
- break;
- id = id >> IDR_BITS;
- __set_bit((id & IDR_MASK), p->bitmap);
- }
+ return __radix_idr_ptr(ret);
}
+EXPORT_SYMBOL(idr_find_next);
/**
- * sub_alloc - try to allocate an id without growing the tree depth
- * @idp: idr handle
- * @starting_id: id to start search at
- * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
- * @gfp_mask: allocation mask for idr_layer_alloc()
- * @layer_idr: optional idr passed to idr_layer_alloc()
+ * idr_for_each - iterate through all stored pointers
+ * @idr: idr handle
+ * @fn: function to be called for each pointer
+ * @data: data passed back to callback function
+ *
+ * Iterate over the pointers registered with the given idr. The
+ * callback function will be called for each pointer currently
+ * registered, passing the id, the pointer and the data pointer passed
+ * to this function. It is not safe to modify the idr tree while in
+ * the callback, so functions such as idr_remove are not allowed.
*
- * Allocate an id in range [@starting_id, INT_MAX] from @idp without
- * growing its depth. Returns
+ * We check the return of @fn each time. If it returns anything other
+ * than %0, we break out and return that value.
*
- * the allocated id >= 0 if successful,
- * -EAGAIN if the tree needs to grow for allocation to succeed,
- * -ENOSPC if the id space is exhausted,
- * -ENOMEM if more idr_layers need to be allocated.
+ * The caller must serialize idr_for_each() vs idr_remove().
*/
-static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
- gfp_t gfp_mask, struct idr *layer_idr)
+int idr_for_each(struct idr *idr,
+ int (*fn)(int id, void *p, void *data), void *data)
{
- int n, m, sh;
- struct idr_layer *p, *new;
- int l, id, oid;
-
- id = *starting_id;
- restart:
- p = idp->top;
- l = idp->layers;
- pa[l--] = NULL;
- while (1) {
- /*
- * We run around this while until we reach the leaf node...
- */
- n = (id >> (IDR_BITS*l)) & IDR_MASK;
- m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
- if (m == IDR_SIZE) {
- /* no space available go back to previous layer. */
- l++;
- oid = id;
- id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
-
- /* if already at the top layer, we need to grow */
- if (id >= 1 << (idp->layers * IDR_BITS)) {
- *starting_id = id;
- return -EAGAIN;
- }
- p = pa[l];
- BUG_ON(!p);
+ void *p;
+ unsigned id;
+ int error = 0;
- /* If we need to go up one layer, continue the
- * loop; otherwise, restart from the top.
- */
- sh = IDR_BITS * (l + 1);
- if (oid >> sh == id >> sh)
- continue;
- else
- goto restart;
- }
- if (m != n) {
- sh = IDR_BITS*l;
- id = ((id >> sh) ^ n ^ m) << sh;
- }
- if ((id >= MAX_IDR_BIT) || (id < 0))
- return -ENOSPC;
- if (l == 0)
+ idr_for_each_entry(idr, p, id) {
+ error = fn(id, p, data);
+ if (error)
break;
- /*
- * Create the layer below if it is missing.
- */
- if (!p->ary[m]) {
- new = idr_layer_alloc(gfp_mask, layer_idr);
- if (!new)
- return -ENOMEM;
- new->layer = l-1;
- new->prefix = id & idr_layer_prefix_mask(new->layer);
- rcu_assign_pointer(p->ary[m], new);
- p->count++;
- }
- pa[l--] = p;
- p = p->ary[m];
}
- pa[l] = p;
- return id;
+ return error;
}
+EXPORT_SYMBOL(idr_for_each);
-static int idr_get_empty_slot(struct idr *idp, int starting_id,
- struct idr_layer **pa, gfp_t gfp_mask,
- struct idr *layer_idr)
+/**
+ * idr_replace - replace pointer for given id
+ * @idr: idr handle
+ * @ptr: pointer you want associated with the id
+ * @id: lookup key
+ *
+ * Replace the pointer registered with an id and return the old value.
+ * A %-ENOENT return indicates that @id was not found.
+ * A %-EINVAL return indicates that @id was not within valid constraints.
+ */
+void *idr_replace(struct idr *idr, void *ptr, unsigned id)
{
- struct idr_layer *p, *new;
- int layers, v, id;
+ void **slot, *old = ERR_PTR(-ENOENT);
unsigned long flags;
- id = starting_id;
-build_up:
- p = idp->top;
- layers = idp->layers;
- if (unlikely(!p)) {
- if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
- return -ENOMEM;
- p->layer = 0;
- layers = 1;
- }
- /*
- * Add a new layer to the top of the tree if the requested
- * id is larger than the currently allocated space.
- */
- while (id > idr_max(layers)) {
- layers++;
- if (!p->count) {
- /* special case: if the tree is currently empty,
- * then we grow the tree by moving the top node
- * upwards.
- */
- p->layer++;
- WARN_ON_ONCE(p->prefix);
- continue;
- }
- if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
- /*
- * The allocation failed. If we built part of
- * the structure tear it down.
- */
- spin_lock_irqsave(&idp->lock, flags);
- for (new = p; p && p != idp->top; new = p) {
- p = p->ary[0];
- new->ary[0] = NULL;
- new->count = 0;
- bitmap_clear(new->bitmap, 0, IDR_SIZE);
- __move_to_free_list(idp, new);
- }
- spin_unlock_irqrestore(&idp->lock, flags);
- return -ENOMEM;
- }
- new->ary[0] = p;
- new->count = 1;
- new->layer = layers-1;
- new->prefix = id & idr_layer_prefix_mask(new->layer);
- if (bitmap_full(p->bitmap, IDR_SIZE))
- __set_bit(0, new->bitmap);
- p = new;
+ rcu_read_lock();
+ spin_lock_irqsave(&idr->ida.lock, flags);
+
+ slot = radix_tree_lookup_slot(&idr->ptrs, id);
+
+ if (slot) {
+ old = radix_tree_deref_slot(slot);
+ if (old)
+ radix_tree_replace_slot(slot, __idr_radix_ptr(ptr));
}
- rcu_assign_pointer(idp->top, p);
- idp->layers = layers;
- v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
- if (v == -EAGAIN)
- goto build_up;
- return(v);
-}
-/*
- * @id and @pa are from a successful allocation from idr_get_empty_slot().
- * Install the user pointer @ptr and mark the slot full.
- */
-static void idr_fill_slot(struct idr *idr, void *ptr, int id,
- struct idr_layer **pa)
-{
- /* update hint used for lookup, cleared from free_layer() */
- rcu_assign_pointer(idr->hint, pa[0]);
+ spin_unlock_irqrestore(&idr->ida.lock, flags);
+ rcu_read_unlock();
- rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
- pa[0]->count++;
- idr_mark_full(pa, id);
+ return __radix_idr_ptr(old);
}
+EXPORT_SYMBOL(idr_replace);
/**
- * idr_preload - preload for idr_alloc_range()
- * @gfp_mask: allocation mask to use for preloading
- *
- * Preload per-cpu layer buffer for idr_alloc_range(). Can only be used from
- * process context and each idr_preload() invocation should be matched with
- * idr_preload_end(). Note that preemption is disabled while preloaded.
- *
- * The first idr_alloc_range() in the preloaded section can be treated as if it
- * were invoked with @gfp_mask used for preloading. This allows using more
- * permissive allocation masks for idrs protected by spinlocks.
- *
- * For example, if idr_alloc_range() below fails, the failure can be treated as
- * if idr_alloc_range() were called with GFP_KERNEL rather than GFP_NOWAIT.
- *
- * idr_preload(GFP_KERNEL);
- * spin_lock(lock);
- *
- * id = idr_alloc_range(idr, ptr, start, end, GFP_NOWAIT);
- *
- * spin_unlock(lock);
- * idr_preload_end();
- * if (id < 0)
- * error;
+ * idr_remove - remove the given id and free its slot
+ * @idr: idr handle
+ * @id: unique key
*/
-void idr_preload(gfp_t gfp_mask)
+void idr_remove(struct idr *idr, unsigned id)
{
- /*
- * Consuming preload buffer from non-process context breaks preload
- * allocation guarantee. Disallow usage from those contexts.
- */
- WARN_ON_ONCE(in_interrupt());
- might_sleep_if(gfp_mask & __GFP_WAIT);
-
- preempt_disable();
-
- /*
- * idr_alloc_range() is likely to succeed w/o full idr_layer buffer and
- * return value from idr_alloc_range() needs to be checked for failure
- * anyway. Silently give up if allocation fails. The caller can
- * treat failures from idr_alloc_range() as if idr_alloc() were called
- * with @gfp_mask which should be enough.
- */
- while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
- struct idr_layer *new;
-
- preempt_enable();
- new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
- preempt_disable();
- if (!new)
- break;
+ unsigned long flags;
- /* link the new one to per-cpu preload list */
- new->ary[0] = __this_cpu_read(idr_preload_head);
- __this_cpu_write(idr_preload_head, new);
- __this_cpu_inc(idr_preload_cnt);
+ spin_lock_irqsave(&idr->ida.lock, flags);
+
+ radix_tree_delete(&idr->ptrs, id);
+ __ida_remove(&idr->ida, id);
+
+ spin_unlock_irqrestore(&idr->ida.lock, flags);
+}
+EXPORT_SYMBOL(idr_remove);
+
+static int idr_insert(struct idr *idr, void *ptr, unsigned id,
+ gfp_t gfp, unsigned long *flags)
+{
+ int ret = radix_tree_preload(GFP_NOWAIT);
+ if (ret) {
+ spin_unlock_irqrestore(&idr->ida.lock, *flags);
+ ret = radix_tree_preload(gfp);
+ spin_lock_irqsave(&idr->ida.lock, *flags);
+
+ if (ret) {
+ __ida_remove(&idr->ida, id);
+ return ret;
+ }
}
+
+ ret = radix_tree_insert(&idr->ptrs, id, __idr_radix_ptr(ptr));
+ BUG_ON(ret);
+ radix_tree_preload_end();
+ return id;
}
-EXPORT_SYMBOL(idr_preload);
/**
* idr_alloc_range - allocate new idr entry
@@ -1301,43 +1055,34 @@ EXPORT_SYMBOL(idr_preload);
* @ptr: pointer to be associated with the new id
* @start: the minimum id (inclusive)
* @end: the maximum id (exclusive, <= 0 for max)
- * @gfp_mask: memory allocation flags
+ * @gfp: memory allocation flags
*
* Allocate an id in [start, end) and associate it with @ptr. If no ID is
* available in the specified range, returns -ENOSPC. On memory allocation
* failure, returns -ENOMEM.
*
- * Note that @end is treated as max when <= 0. This is to always allow
- * using @start + N as @end as long as N is inside integer range.
- *
- * The user is responsible for exclusively synchronizing all operations
- * which may modify @idr. However, read-only accesses such as idr_find()
- * or iteration can be performed under RCU read lock provided the user
- * destroys @ptr in RCU-safe way after removal from idr.
+ * Note that @end is treated as max when <= 0. This is to always allow using
+ * @start + N as @end as long as N is inside integer range.
*/
-int idr_alloc_range(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
+int idr_alloc_range(struct idr *idr, void *ptr, unsigned start,
+ unsigned end, gfp_t gfp)
{
- int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
- struct idr_layer *pa[MAX_IDR_LEVEL + 1];
- int id;
+ int ret;
+ unsigned id;
+ unsigned long flags;
- might_sleep_if(gfp_mask & __GFP_WAIT);
+ might_sleep_if(gfp & __GFP_WAIT);
- /* sanity checks */
- if (WARN_ON_ONCE(start < 0))
- return -EINVAL;
- if (unlikely(max < start))
- return -ENOSPC;
+ spin_lock_irqsave(&idr->ida.lock, flags);
- /* allocate id */
- id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
- if (unlikely(id < 0))
- return id;
- if (unlikely(id > max))
- return -ENOSPC;
+ ret = __ida_alloc_range_multiple(&idr->ida, &id, 1, start,
+ end, gfp, &flags);
+ if (ret == 1)
+ ret = idr_insert(idr, ptr, id, gfp, &flags);
- idr_fill_slot(idr, ptr, id, pa);
- return id;
+ spin_unlock_irqrestore(&idr->ida.lock, flags);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(idr_alloc_range);
@@ -1349,368 +1094,63 @@ EXPORT_SYMBOL_GPL(idr_alloc_range);
* @end: the maximum id (exclusive, <= 0 for max)
* @gfp_mask: memory allocation flags
*
- * Essentially the same as idr_alloc_range, but prefers to allocate progressively
- * higher ids if it can. If the "cur" counter wraps, then it will start again
- * at the "start" end of the range and allocate one that has already been used.
+ * Essentially the same as idr_alloc_range, but prefers to allocate
+ * progressively higher ids if it can. If the "cur" counter wraps, then it will
+ * start again at the "start" end of the range and allocate one that has already
+ * been used.
*/
-int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
- gfp_t gfp_mask)
+int idr_alloc_cyclic(struct idr *idr, void *ptr, unsigned start,
+ unsigned end, gfp_t gfp)
{
- int id;
+ int ret;
+ unsigned long flags;
- id = idr_alloc_range(idr, ptr, max(start, idr->cur), end, gfp_mask);
- if (id == -ENOSPC)
- id = idr_alloc_range(idr, ptr, start, end, gfp_mask);
+ might_sleep_if(gfp & __GFP_WAIT);
- if (likely(id >= 0))
- idr->cur = id + 1;
- return id;
-}
-EXPORT_SYMBOL(idr_alloc_cyclic);
+ spin_lock_irqsave(&idr->ida.lock, flags);
-static void idr_remove_warning(int id)
-{
- printk(KERN_WARNING
- "idr_remove called for id=%d which is not allocated.\n", id);
- dump_stack();
-}
+ ret = __ida_alloc_cyclic(&idr->ida, start, end, gfp, &flags);
+ if (ret >= 0)
+ ret = idr_insert(idr, ptr, ret, gfp, &flags);
-static void sub_remove(struct idr *idp, int shift, int id)
-{
- struct idr_layer *p = idp->top;
- struct idr_layer **pa[MAX_IDR_LEVEL + 1];
- struct idr_layer ***paa = &pa[0];
- struct idr_layer *to_free;
- int n;
-
- *paa = NULL;
- *++paa = &idp->top;
-
- while ((shift > 0) && p) {
- n = (id >> shift) & IDR_MASK;
- __clear_bit(n, p->bitmap);
- *++paa = &p->ary[n];
- p = p->ary[n];
- shift -= IDR_BITS;
- }
- n = id & IDR_MASK;
- if (likely(p != NULL && test_bit(n, p->bitmap))) {
- __clear_bit(n, p->bitmap);
- rcu_assign_pointer(p->ary[n], NULL);
- to_free = NULL;
- while(*paa && ! --((**paa)->count)){
- if (to_free)
- free_layer(idp, to_free);
- to_free = **paa;
- **paa-- = NULL;
- }
- if (!*paa)
- idp->layers = 0;
- if (to_free)
- free_layer(idp, to_free);
- } else
- idr_remove_warning(id);
-}
+ spin_unlock_irqrestore(&idr->ida.lock, flags);
-/**
- * idr_remove - remove the given id and free its slot
- * @idp: idr handle
- * @id: unique key
- */
-void idr_remove(struct idr *idp, int id)
-{
- struct idr_layer *p;
- struct idr_layer *to_free;
-
- if (id < 0)
- return;
-
- sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
- if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
- 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];
- rcu_assign_pointer(idp->top, p);
- --idp->layers;
- to_free->count = 0;
- bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
- free_layer(idp, to_free);
- }
- while (idp->id_free_cnt >= MAX_IDR_FREE) {
- 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;
-}
-EXPORT_SYMBOL(idr_remove);
-
-static void __idr_remove_all(struct idr *idp)
-{
- int n, id, max;
- int bt_mask;
- struct idr_layer *p;
- struct idr_layer *pa[MAX_IDR_LEVEL + 1];
- struct idr_layer **paa = &pa[0];
-
- n = idp->layers * IDR_BITS;
- p = idp->top;
- rcu_assign_pointer(idp->top, NULL);
- max = idr_max(idp->layers);
-
- id = 0;
- while (id >= 0 && id <= max) {
- while (n > IDR_BITS && p) {
- n -= IDR_BITS;
- *paa++ = p;
- p = p->ary[(id >> n) & IDR_MASK];
- }
-
- bt_mask = id;
- id += 1 << n;
- /* Get the highest bit that the above add changed from 0->1. */
- while (n < fls(id ^ bt_mask)) {
- if (p)
- free_layer(idp, p);
- n += IDR_BITS;
- p = *--paa;
- }
- }
- idp->layers = 0;
+ return ret;
}
+EXPORT_SYMBOL(idr_alloc_cyclic);
/**
- * idr_destroy - release all cached layers within an idr tree
- * @idp: idr handle
+ * idr_destroy - free all memory owned by @idr
+ * @idr: idr handle
*
- * Free all id mappings and all idp_layers. After this function, @idp is
- * completely unused and can be freed / recycled. The caller is
- * responsible for ensuring that no one else accesses @idp during or after
- * idr_destroy().
+ * After this function, @idr is completely unused and can be freed / recycled.
*
* A typical clean-up sequence for objects stored in an idr tree will use
* idr_for_each() to free all objects, if necessay, then idr_destroy() to
- * free up the id mappings and cached idr_layers.
- */
-void idr_destroy(struct idr *idp)
-{
- __idr_remove_all(idp);
-
- while (idp->id_free_cnt) {
- struct idr_layer *p = get_from_free_list(idp);
- kmem_cache_free(idr_layer_cache, p);
- }
-}
-EXPORT_SYMBOL(idr_destroy);
-
-void *idr_find_slowpath(struct idr *idp, int id)
-{
- int n;
- struct idr_layer *p;
-
- if (id < 0)
- return NULL;
-
- p = rcu_dereference_raw(idp->top);
- if (!p)
- return NULL;
- n = (p->layer+1) * IDR_BITS;
-
- if (id > idr_max(p->layer + 1))
- return NULL;
- BUG_ON(n == 0);
-
- while (n > 0 && p) {
- n -= IDR_BITS;
- BUG_ON(n != p->layer*IDR_BITS);
- p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
- }
- return((void *)p);
-}
-EXPORT_SYMBOL(idr_find_slowpath);
-
-/**
- * idr_for_each - iterate through all stored pointers
- * @idp: idr handle
- * @fn: function to be called for each pointer
- * @data: data passed back to callback function
- *
- * Iterate over the pointers registered with the given idr. The
- * callback function will be called for each pointer currently
- * registered, passing the id, the pointer and the data pointer passed
- * to this function. It is not safe to modify the idr tree while in
- * the callback, so functions such as idr_remove are not allowed.
- *
- * We check the return of @fn each time. If it returns anything other
- * than %0, we break out and return that value.
- *
- * The caller must serialize idr_for_each() vs idr_remove().
+ * free the embedded ida and radix tree.
*/
-int idr_for_each(struct idr *idp,
- int (*fn)(int id, void *p, void *data), void *data)
+void idr_destroy(struct idr *idr)
{
- int n, id, max, error = 0;
- struct idr_layer *p;
- struct idr_layer *pa[MAX_IDR_LEVEL + 1];
- struct idr_layer **paa = &pa[0];
-
- n = idp->layers * IDR_BITS;
- p = rcu_dereference_raw(idp->top);
- max = idr_max(idp->layers);
-
- id = 0;
- while (id >= 0 && id <= max) {
- while (n > 0 && p) {
- n -= IDR_BITS;
- *paa++ = p;
- p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
- }
-
- if (p) {
- error = fn(id, (void *)p, data);
- if (error)
- break;
- }
-
- id += 1 << n;
- while (n < fls(id)) {
- n += IDR_BITS;
- p = *--paa;
- }
- }
-
- return error;
-}
-EXPORT_SYMBOL(idr_for_each);
-
-/**
- * idr_find_next - lookup next object of id to given id.
- * @idp: idr handle
- * @nextidp: pointer to lookup key
- *
- * Returns pointer to registered object with id, which is next number to
- * given id. After being looked up, *@...tidp will be updated for the next
- * iteration.
- *
- * This function can be called under rcu_read_lock(), given that the leaf
- * pointers lifetimes are correctly managed.
- */
-void *idr_find_next(struct idr *idp, int *nextidp)
-{
- struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
- struct idr_layer **paa = &pa[0];
- int id = *nextidp;
- int n, max;
-
- /* find first ent */
- p = rcu_dereference_raw(idp->top);
- if (!p)
- return NULL;
- n = (p->layer + 1) * IDR_BITS;
- max = idr_max(p->layer + 1);
-
- while (id >= 0 && id <= max) {
- while (n > 0 && p) {
- n -= IDR_BITS;
- *paa++ = p;
- p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
- }
-
- if (p) {
- *nextidp = id;
- return p;
- }
-
- /*
- * Proceed to the next layer at the current level. Unlike
- * idr_for_each(), @id isn't guaranteed to be aligned to
- * layer boundary at this point and adding 1 << n may
- * incorrectly skip IDs. Make sure we jump to the
- * beginning of the next layer using round_up().
- */
- id = round_up(id + 1, 1 << n);
- while (n < fls(id)) {
- n += IDR_BITS;
- p = *--paa;
- }
- }
- return NULL;
-}
-EXPORT_SYMBOL(idr_find_next);
-
-
-/**
- * idr_replace - replace pointer for given id
- * @idp: idr handle
- * @ptr: pointer you want associated with the id
- * @id: lookup key
- *
- * Replace the pointer registered with an id and return the old value.
- * A %-ENOENT return indicates that @id was not found.
- * A %-EINVAL return indicates that @id was not within valid constraints.
- *
- * The caller must serialize with writers.
- */
-void *idr_replace(struct idr *idp, void *ptr, int id)
-{
- int n;
- struct idr_layer *p, *old_p;
-
- if (id < 0)
- return ERR_PTR(-EINVAL);
-
- p = idp->top;
- if (!p)
- return ERR_PTR(-EINVAL);
-
- n = (p->layer+1) * IDR_BITS;
-
- if (id >= (1 << n))
- return ERR_PTR(-EINVAL);
-
- n -= IDR_BITS;
- while ((n > 0) && p) {
- p = p->ary[(id >> n) & IDR_MASK];
- n -= IDR_BITS;
- }
-
- n = id & IDR_MASK;
- if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
- return ERR_PTR(-ENOENT);
-
- old_p = p->ary[n];
- rcu_assign_pointer(p->ary[n], ptr);
+ void *p;
+ unsigned id;
- return old_p;
-}
-EXPORT_SYMBOL(idr_replace);
+ idr_for_each_entry(idr, p, id)
+ idr_remove(idr, id);
-void __init idr_init_cache(void)
-{
- idr_layer_cache = kmem_cache_create("idr_layer_cache",
- sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
+ ida_destroy(&idr->ida);
}
+EXPORT_SYMBOL(idr_destroy);
/**
- * idr_init - initialize idr handle
- * @idp: idr handle
+ * idr_init - initialize sparse idr handle
+ * @idr: idr handle
*
- * This function is use to set up the handle (@idp) that you will pass
+ * This function is use to set up the handle (@idr) that you will pass
* to the rest of the functions.
*/
-void idr_init(struct idr *idp)
+void idr_init(struct idr *idr)
{
- memset(idp, 0, sizeof(struct idr));
- spin_lock_init(&idp->lock);
+ ida_init(&idr->ida);
+ INIT_RADIX_TREE(&idr->ptrs, GFP_NOWAIT);
}
EXPORT_SYMBOL(idr_init);
--
1.8.3.2
--
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