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Commit 460488c5 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

idr: Remove idr_alloc_ext 



It has no more users, so remove it.  Move idr_alloc() back into idr.c,
move the guts of idr_alloc_cmn() into idr_alloc_u32(), remove the
wrappers around idr_get_free_cmn() and rename it to idr_get_free().
While there is now no interface to allocate IDs larger than a u32,
the IDR internals remain ready to handle a larger ID should a need arise.

These changes make it possible to provide the guarantee that, if the
nextid pointer points into the object, the object's ID will be initialised
before a concurrent lookup can find the object.

Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
parent f730cb93

include/linux/idr.h

+1 −50
Original line number Diff line number Diff line
@@ -15,7 +15,6 @@ 
#include <linux/radix-tree.h>

#include <linux/gfp.h>

#include <linux/percpu.h>

#include <linux/bug.h>



struct idr {

	struct radix_tree_root	idr_rt;
@@ -82,55 +81,7 @@ static inline void idr_set_cursor(struct idr *idr, unsigned int val) 


void idr_preload(gfp_t gfp_mask);



int idr_alloc_cmn(struct idr *idr, void *ptr, unsigned long *index,

		  unsigned long start, unsigned long end, gfp_t gfp,

		  bool ext);



/**

 * idr_alloc - allocate an id

 * @idr: idr handle

 * @ptr: pointer to be associated with the new id

 * @start: the minimum id (inclusive)

 * @end: the maximum id (exclusive)

 * @gfp: memory allocation flags

 *

 * Allocates an unused ID in the range [start, end).  Returns -ENOSPC

 * if there are no unused IDs in that range.

 *

 * 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.

 *

 * Simultaneous modifications to the @idr are not allowed and should be

 * prevented by the user, usually with a lock.  idr_alloc() may be called

 * concurrently with read-only accesses to the @idr, such as idr_find() and

 * idr_for_each_entry().

 */

static inline int idr_alloc(struct idr *idr, void *ptr,

			    int start, int end, gfp_t gfp)

{

	unsigned long id;

	int ret;



	if (WARN_ON_ONCE(start < 0))

		return -EINVAL;



	ret = idr_alloc_cmn(idr, ptr, &id, start, end, gfp, false);



	if (ret)

		return ret;



	return id;

}



static inline int idr_alloc_ext(struct idr *idr, void *ptr,

				unsigned long *index,

				unsigned long start,

				unsigned long end,

				gfp_t gfp)

{

	return idr_alloc_cmn(idr, ptr, index, start, end, gfp, true);

}



int idr_alloc(struct idr *, void *, int start, int end, gfp_t);

int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *nextid,

				unsigned long max, gfp_t);

int idr_alloc_cyclic(struct idr *, void *entry, int start, int end, gfp_t);

include/linux/radix-tree.h

+1 −16
Original line number Diff line number Diff line
@@ -356,24 +356,9 @@ int radix_tree_split(struct radix_tree_root *, unsigned long index, 
int radix_tree_join(struct radix_tree_root *, unsigned long index,

			unsigned new_order, void *);



void __rcu **idr_get_free_cmn(struct radix_tree_root *root,

void __rcu **idr_get_free(struct radix_tree_root *root,

			      struct radix_tree_iter *iter, gfp_t gfp,

			      unsigned long max);

static inline void __rcu **idr_get_free(struct radix_tree_root *root,

					struct radix_tree_iter *iter,

					gfp_t gfp,

					int end)

{

	return idr_get_free_cmn(root, iter, gfp, end > 0 ? end - 1 : INT_MAX);

}



static inline void __rcu **idr_get_free_ext(struct radix_tree_root *root,

					    struct radix_tree_iter *iter,

					    gfp_t gfp,

					    unsigned long end)

{

	return idr_get_free_cmn(root, iter, gfp, end - 1);

}



enum {

	RADIX_TREE_ITER_TAG_MASK = 0x0f,	/* tag index in lower nybble */

lib/idr.c

+84 −44
Original line number Diff line number Diff line 
#include <linux/bitmap.h>

#include <linux/bug.h>

#include <linux/export.h>

#include <linux/idr.h>

#include <linux/slab.h>
@@ -17,7 +18,9 @@ static DEFINE_SPINLOCK(simple_ida_lock); 
 *

 * Allocates an unused ID in the range specified by @nextid and @max.

 * Note that @max is inclusive whereas the @end parameter to idr_alloc()

 * is exclusive.

 * is exclusive.  The new ID is assigned to @nextid before the pointer

 * is inserted into the IDR, so if @nextid points into the object pointed

 * to by @ptr, a concurrent lookup will not find an uninitialised ID.

 *

 * The caller should provide their own locking to ensure that two

 * concurrent modifications to the IDR are not possible.  Read-only
@@ -30,67 +33,104 @@ static DEFINE_SPINLOCK(simple_ida_lock); 
 */

int idr_alloc_u32(struct idr *idr, void *ptr, u32 *nextid,

			unsigned long max, gfp_t gfp)

{

	unsigned long tmp = *nextid;

	int ret = idr_alloc_ext(idr, ptr, &tmp, tmp, max + 1, gfp);

	*nextid = tmp;

	return ret;

}

EXPORT_SYMBOL_GPL(idr_alloc_u32);



int idr_alloc_cmn(struct idr *idr, void *ptr, unsigned long *index,

		  unsigned long start, unsigned long end, gfp_t gfp,

		  bool ext)

{

	struct radix_tree_iter iter;

	void __rcu **slot;



	if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))

		return -EINVAL;

	if (WARN_ON_ONCE(!(idr->idr_rt.gfp_mask & ROOT_IS_IDR)))

		idr->idr_rt.gfp_mask |= IDR_RT_MARKER;



	radix_tree_iter_init(&iter, start);

	if (ext)

		slot = idr_get_free_ext(&idr->idr_rt, &iter, gfp, end);

	else

		slot = idr_get_free(&idr->idr_rt, &iter, gfp, end);

	radix_tree_iter_init(&iter, *nextid);

	slot = idr_get_free(&idr->idr_rt, &iter, gfp, max);

	if (IS_ERR(slot))

		return PTR_ERR(slot);



	*nextid = iter.index;

	/* there is a memory barrier inside radix_tree_iter_replace() */

	radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr);

	radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE);



	if (index)

		*index = iter.index;

	return 0;

}

EXPORT_SYMBOL_GPL(idr_alloc_cmn);

EXPORT_SYMBOL_GPL(idr_alloc_u32);



/**

 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion

 * @idr: idr handle

 * @ptr: pointer to be associated with the new id

 * @start: the minimum id (inclusive)

 * @end: the maximum id (exclusive)

 * @gfp: memory allocation flags

 *

 * Allocates an ID larger than the last ID allocated if one is available.

 * If not, it will attempt to allocate the smallest ID that is larger or

 * equal to @start.

 * idr_alloc() - Allocate an ID.

 * @idr: IDR handle.

 * @ptr: Pointer to be associated with the new ID.

 * @start: The minimum ID (inclusive).

 * @end: The maximum ID (exclusive).

 * @gfp: Memory allocation flags.

 *

 * Allocates an unused ID in the range specified by @start and @end.  If

 * @end is <= 0, it is treated as one larger than %INT_MAX.  This allows

 * callers to use @start + N as @end as long as N is within integer range.

 *

 * The caller should provide their own locking to ensure that two

 * concurrent modifications to the IDR are not possible.  Read-only

 * accesses to the IDR may be done under the RCU read lock or may

 * exclude simultaneous writers.

 *

 * Return: The newly allocated ID, -ENOMEM if memory allocation failed,

 * or -ENOSPC if no free IDs could be found.

 */

int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)

int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)

{

	int id, curr = idr->idr_next;

	u32 id = start;

	int ret;



	if (WARN_ON_ONCE(start < 0))

		return -EINVAL;



	ret = idr_alloc_u32(idr, ptr, &id, end > 0 ? end - 1 : INT_MAX, gfp);

	if (ret)

		return ret;



	return id;

}

EXPORT_SYMBOL_GPL(idr_alloc);



	if (curr < start)

		curr = start;

/**

 * idr_alloc_cyclic() - Allocate an ID cyclically.

 * @idr: IDR handle.

 * @ptr: Pointer to be associated with the new ID.

 * @start: The minimum ID (inclusive).

 * @end: The maximum ID (exclusive).

 * @gfp: Memory allocation flags.

 *

 * Allocates an unused ID in the range specified by @nextid and @end.  If

 * @end is <= 0, it is treated as one larger than %INT_MAX.  This allows

 * callers to use @start + N as @end as long as N is within integer range.

 * The search for an unused ID will start at the last ID allocated and will

 * wrap around to @start if no free IDs are found before reaching @end.

 *

 * The caller should provide their own locking to ensure that two

 * concurrent modifications to the IDR are not possible.  Read-only

 * accesses to the IDR may be done under the RCU read lock or may

 * exclude simultaneous writers.

 *

 * Return: The newly allocated ID, -ENOMEM if memory allocation failed,

 * or -ENOSPC if no free IDs could be found.

 */

int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)

{

	u32 id = idr->idr_next;

	int err, max = end > 0 ? end - 1 : INT_MAX;



	id = idr_alloc(idr, ptr, curr, end, gfp);

	if ((id == -ENOSPC) && (curr > start))

		id = idr_alloc(idr, ptr, start, curr, gfp);

	if ((int)id < start)

		id = start;



	if (id >= 0)

		idr->idr_next = id + 1U;

	err = idr_alloc_u32(idr, ptr, &id, max, gfp);

	if ((err == -ENOSPC) && (id > start)) {

		id = start;

		err = idr_alloc_u32(idr, ptr, &id, max, gfp);

	}

	if (err)

		return err;



	idr->idr_next = id + 1;

	return id;

}

EXPORT_SYMBOL(idr_alloc_cyclic);
@@ -167,10 +207,10 @@ void *idr_get_next_ext(struct idr *idr, unsigned long *nextid) 
EXPORT_SYMBOL(idr_get_next_ext);



/**

 * idr_replace - replace pointer for given id

 * @idr: idr handle

 * @ptr: New pointer to associate with the ID

 * @id: Lookup key

 * idr_replace() - replace pointer for given ID.

 * @idr: IDR handle.

 * @ptr: New pointer to associate with the ID.

 * @id: ID to change.

 *

 * Replace the pointer registered with an ID and return the old value.

 * This function can be called under the RCU read lock concurrently with
@@ -257,7 +297,7 @@ EXPORT_SYMBOL(idr_replace); 
 * bitmap, which is excessive.

 */



#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS)

#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS - 1)



/**

 * ida_get_new_above - allocate new ID above or equal to a start id

lib/radix-tree.c

+2 −1
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 


#include <linux/bitmap.h>

#include <linux/bitops.h>

#include <linux/bug.h>

#include <linux/cpu.h>

#include <linux/errno.h>

#include <linux/export.h>
@@ -2135,7 +2136,7 @@ int ida_pre_get(struct ida *ida, gfp_t gfp) 
}

EXPORT_SYMBOL(ida_pre_get);



void __rcu **idr_get_free_cmn(struct radix_tree_root *root,

void __rcu **idr_get_free(struct radix_tree_root *root,

			      struct radix_tree_iter *iter, gfp_t gfp,

			      unsigned long max)

{

tools/testing/radix-tree/idr-test.c

+17 −0
Original line number Diff line number Diff line
@@ -215,6 +215,23 @@ void idr_checks(void) 


	assert(idr_is_empty(&idr));



	idr_set_cursor(&idr, INT_MAX - 3UL);

	for (i = INT_MAX - 3UL; i < INT_MAX + 3UL; i++) {

		struct item *item;

		unsigned int id;

		if (i <= INT_MAX)

			item = item_create(i, 0);

		else

			item = item_create(i - INT_MAX - 1, 0);



		id = idr_alloc_cyclic(&idr, item, 0, 0, GFP_KERNEL);

		assert(id == item->index);

	}



	idr_for_each(&idr, item_idr_free, &idr);

	idr_destroy(&idr);

	assert(idr_is_empty(&idr));



	for (i = 1; i < 10000; i++) {

		struct item *item = item_create(i, 0);

		assert(idr_alloc(&idr, item, 1, 20000, GFP_KERNEL) == i);