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Commit e096f6a7 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

idr: Add idr_alloc_u32 helper 



All current users of idr_alloc_ext() actually want to allocate a u32
and idr_alloc_u32() fits their needs better.

Like idr_get_next(), it uses a 'nextid' argument which serves as both
a pointer to the start ID and the assigned ID (instead of a separate
minimum and pointer-to-assigned-ID argument).  It uses a 'max' argument
rather than 'end' because the semantics that idr_alloc has for 'end'
don't work well for unsigned types.

Since idr_alloc_u32() returns an errno instead of the allocated ID, mark
it as __must_check to help callers use it correctly.  Include copious
kernel-doc.  Chris Mi <chrism@mellanox.com> has promised to contribute
test-cases for idr_alloc_u32.

Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
parent 322d884b

include/linux/idr.h

+2 −0
Original line number Diff line number Diff line
@@ -131,6 +131,8 @@ static inline int idr_alloc_ext(struct idr *idr, void *ptr, 
	return idr_alloc_cmn(idr, ptr, index, start, end, gfp, true);

}



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);

int idr_for_each(const struct idr *,

		 int (*fn)(int id, void *p, void *data), void *data);

lib/idr.c

+31 −0
Original line number Diff line number Diff line
@@ -7,6 +7,37 @@ 
DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap);

static DEFINE_SPINLOCK(simple_ida_lock);



/**

 * idr_alloc_u32() - Allocate an ID.

 * @idr: IDR handle.

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

 * @nextid: Pointer to an ID.

 * @max: The maximum ID to allocate (inclusive).

 * @gfp: Memory allocation flags.

 *

 * 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.

 *

 * 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: 0 if an ID was allocated, -ENOMEM if memory allocation failed,

 * or -ENOSPC if no free IDs could be found.  If an error occurred,

 * @nextid is unchanged.

 */

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)