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Commit 88eca020 authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
Browse files

ida: simplified functions for id allocation 



The current hyper-optimized functions are overkill if you simply want to
allocate an id for a device.  Create versions which use an internal
lock.

In followup patches, numerous drivers are converted to use this
interface.

Thanks to Tejun for feedback.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a7295898

include/linux/idr.h

+4 −0
Original line number Diff line number Diff line
@@ -146,6 +146,10 @@ void ida_remove(struct ida *ida, int id); 
void ida_destroy(struct ida *ida);

void ida_init(struct ida *ida);



int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,

		   gfp_t gfp_mask);

void ida_simple_remove(struct ida *ida, unsigned int id);



void __init idr_init_cache(void);



#endif /* __IDR_H__ */

lib/idr.c

+67 −0
Original line number Diff line number Diff line
@@ -34,8 +34,10 @@ 
#include <linux/err.h>

#include <linux/string.h>

#include <linux/idr.h>

#include <linux/spinlock.h>



static struct kmem_cache *idr_layer_cache;

static DEFINE_SPINLOCK(simple_ida_lock);



static struct idr_layer *get_from_free_list(struct idr *idp)

{
@@ -925,6 +927,71 @@ void ida_destroy(struct ida *ida) 
}

EXPORT_SYMBOL(ida_destroy);



/**

 * ida_simple_get - get a new id.

 * @ida: the (initialized) ida.

 * @start: the minimum id (inclusive, < 0x8000000)

 * @end: the maximum id (exclusive, < 0x8000000 or 0)

 * @gfp_mask: memory allocation flags

 *

 * Allocates an id in the range start <= id < end, or returns -ENOSPC.

 * On memory allocation failure, returns -ENOMEM.

 *

 * Use ida_simple_remove() to get rid of an id.

 */

int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,

		   gfp_t gfp_mask)

{

	int ret, id;

	unsigned int max;



	BUG_ON((int)start < 0);

	BUG_ON((int)end < 0);



	if (end == 0)

		max = 0x80000000;

	else {

		BUG_ON(end < start);

		max = end - 1;

	}



again:

	if (!ida_pre_get(ida, gfp_mask))

		return -ENOMEM;



	spin_lock(&simple_ida_lock);

	ret = ida_get_new_above(ida, start, &id);

	if (!ret) {

		if (id > max) {

			ida_remove(ida, id);

			ret = -ENOSPC;

		} else {

			ret = id;

		}

	}

	spin_unlock(&simple_ida_lock);



	if (unlikely(ret == -EAGAIN))

		goto again;



	return ret;

}

EXPORT_SYMBOL(ida_simple_get);



/**

 * ida_simple_remove - remove an allocated id.

 * @ida: the (initialized) ida.

 * @id: the id returned by ida_simple_get.

 */

void ida_simple_remove(struct ida *ida, unsigned int id)

{

	BUG_ON((int)id < 0);

	spin_lock(&simple_ida_lock);

	ida_remove(ida, id);

	spin_unlock(&simple_ida_lock);

}

EXPORT_SYMBOL(ida_simple_remove);



/**

 * ida_init - initialize ida handle

 * @ida:	ida handle