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ida: Add ida_find_first_range()
commit 7fe6b98 Author: Yi Liu <yi.l.liu@intel.com> Date: Fri Mar 21 11:01:39 2025 -0700 ida: Add ida_find_first_range() There is no helpers for user to check if a given ID is allocated or not, neither a helper to loop all the allocated IDs in an IDA and do something for cleanup. With the two needs, a helper to get the lowest allocated ID of a range and two variants based on it. Caller can check if a given ID is allocated or not by: bool ida_exists(struct ida *ida, unsigned int id) Caller can iterate all allocated IDs by: int id; while ((id = ida_find_first(&pasid_ida)) >= 0) { //anything to do with the allocated ID ida_free(pasid_ida, pasid); } Link: https://patch.msgid.link/r/20250321180143.8468-2-yi.l.liu@intel.com Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org> Tested-by: Nicolin Chen <nicolinc@nvidia.com> Signed-off-by: Yi Liu <yi.l.liu@intel.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> (cherry picked from commit 7fe6b98) Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com> Upstream-Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git JIRA: https://issues.redhat.com/browse/RHEL-73603
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‎include/linux/idr.h‎

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -257,6 +257,7 @@ struct ida {
257257
int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
258258
void ida_free(struct ida *, unsigned int id);
259259
void ida_destroy(struct ida *ida);
260+
int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max);
260261

261262
/**
262263
* ida_alloc() - Allocate an unused ID.
@@ -328,4 +329,14 @@ static inline bool ida_is_empty(const struct ida *ida)
328329
{
329330
return xa_empty(&ida->xa);
330331
}
332+
333+
static inline bool ida_exists(struct ida *ida, unsigned int id)
334+
{
335+
return ida_find_first_range(ida, id, id) == id;
336+
}
337+
338+
static inline int ida_find_first(struct ida *ida)
339+
{
340+
return ida_find_first_range(ida, 0, ~0);
341+
}
331342
#endif /* __IDR_H__ */

‎lib/idr.c‎

Lines changed: 67 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -476,6 +476,73 @@ int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
476476
}
477477
EXPORT_SYMBOL(ida_alloc_range);
478478

479+
/**
480+
* ida_find_first_range - Get the lowest used ID.
481+
* @ida: IDA handle.
482+
* @min: Lowest ID to get.
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* @max: Highest ID to get.
484+
*
485+
* Get the lowest used ID between @min and @max, inclusive. The returned
486+
* ID will not exceed %INT_MAX, even if @max is larger.
487+
*
488+
* Context: Any context. Takes and releases the xa_lock.
489+
* Return: The lowest used ID, or errno if no used ID is found.
490+
*/
491+
int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max)
492+
{
493+
unsigned long index = min / IDA_BITMAP_BITS;
494+
unsigned int offset = min % IDA_BITMAP_BITS;
495+
unsigned long *addr, size, bit;
496+
unsigned long tmp = 0;
497+
unsigned long flags;
498+
void *entry;
499+
int ret;
500+
501+
if ((int)min < 0)
502+
return -EINVAL;
503+
if ((int)max < 0)
504+
max = INT_MAX;
505+
506+
xa_lock_irqsave(&ida->xa, flags);
507+
508+
entry = xa_find(&ida->xa, &index, max / IDA_BITMAP_BITS, XA_PRESENT);
509+
if (!entry) {
510+
ret = -ENOENT;
511+
goto err_unlock;
512+
}
513+
514+
if (index > min / IDA_BITMAP_BITS)
515+
offset = 0;
516+
if (index * IDA_BITMAP_BITS + offset > max) {
517+
ret = -ENOENT;
518+
goto err_unlock;
519+
}
520+
521+
if (xa_is_value(entry)) {
522+
tmp = xa_to_value(entry);
523+
addr = &tmp;
524+
size = BITS_PER_XA_VALUE;
525+
} else {
526+
addr = ((struct ida_bitmap *)entry)->bitmap;
527+
size = IDA_BITMAP_BITS;
528+
}
529+
530+
bit = find_next_bit(addr, size, offset);
531+
532+
xa_unlock_irqrestore(&ida->xa, flags);
533+
534+
if (bit == size ||
535+
index * IDA_BITMAP_BITS + bit > max)
536+
return -ENOENT;
537+
538+
return index * IDA_BITMAP_BITS + bit;
539+
540+
err_unlock:
541+
xa_unlock_irqrestore(&ida->xa, flags);
542+
return ret;
543+
}
544+
EXPORT_SYMBOL(ida_find_first_range);
545+
479546
/**
480547
* ida_free() - Release an allocated ID.
481548
* @ida: IDA handle.

‎lib/test_ida.c‎

Lines changed: 70 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -189,6 +189,75 @@ static void ida_check_bad_free(struct ida *ida)
189189
IDA_BUG_ON(ida, !ida_is_empty(ida));
190190
}
191191

192+
/*
193+
* Check ida_find_first_range() and varriants.
194+
*/
195+
static void ida_check_find_first(struct ida *ida)
196+
{
197+
/* IDA is empty; all of the below should be not exist */
198+
IDA_BUG_ON(ida, ida_exists(ida, 0));
199+
IDA_BUG_ON(ida, ida_exists(ida, 3));
200+
IDA_BUG_ON(ida, ida_exists(ida, 63));
201+
IDA_BUG_ON(ida, ida_exists(ida, 1023));
202+
IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
203+
204+
/* IDA contains a single value entry */
205+
IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3);
206+
IDA_BUG_ON(ida, ida_exists(ida, 0));
207+
IDA_BUG_ON(ida, !ida_exists(ida, 3));
208+
IDA_BUG_ON(ida, ida_exists(ida, 63));
209+
IDA_BUG_ON(ida, ida_exists(ida, 1023));
210+
IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
211+
212+
IDA_BUG_ON(ida, ida_alloc_min(ida, 63, GFP_KERNEL) != 63);
213+
IDA_BUG_ON(ida, ida_exists(ida, 0));
214+
IDA_BUG_ON(ida, !ida_exists(ida, 3));
215+
IDA_BUG_ON(ida, !ida_exists(ida, 63));
216+
IDA_BUG_ON(ida, ida_exists(ida, 1023));
217+
IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
218+
219+
/* IDA contains a single bitmap */
220+
IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023);
221+
IDA_BUG_ON(ida, ida_exists(ida, 0));
222+
IDA_BUG_ON(ida, !ida_exists(ida, 3));
223+
IDA_BUG_ON(ida, !ida_exists(ida, 63));
224+
IDA_BUG_ON(ida, !ida_exists(ida, 1023));
225+
IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
226+
227+
/* IDA contains a tree */
228+
IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1);
229+
IDA_BUG_ON(ida, ida_exists(ida, 0));
230+
IDA_BUG_ON(ida, !ida_exists(ida, 3));
231+
IDA_BUG_ON(ida, !ida_exists(ida, 63));
232+
IDA_BUG_ON(ida, !ida_exists(ida, 1023));
233+
IDA_BUG_ON(ida, !ida_exists(ida, (1 << 20) - 1));
234+
235+
/* Now try to find first */
236+
IDA_BUG_ON(ida, ida_find_first(ida) != 3);
237+
IDA_BUG_ON(ida, ida_find_first_range(ida, -1, 2) != -EINVAL);
238+
IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 2) != -ENOENT); // no used ID
239+
IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 3) != 3);
240+
IDA_BUG_ON(ida, ida_find_first_range(ida, 1, 3) != 3);
241+
IDA_BUG_ON(ida, ida_find_first_range(ida, 3, 3) != 3);
242+
IDA_BUG_ON(ida, ida_find_first_range(ida, 2, 4) != 3);
243+
IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 3) != -ENOENT); // min > max, fail
244+
IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 60) != -ENOENT); // no used ID
245+
IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 64) != 63);
246+
IDA_BUG_ON(ida, ida_find_first_range(ida, 63, 63) != 63);
247+
IDA_BUG_ON(ida, ida_find_first_range(ida, 64, 1026) != 1023);
248+
IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, 1023) != 1023);
249+
IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, (1 << 20) - 1) != 1023);
250+
IDA_BUG_ON(ida, ida_find_first_range(ida, 1024, (1 << 20) - 1) != (1 << 20) - 1);
251+
IDA_BUG_ON(ida, ida_find_first_range(ida, (1 << 20), INT_MAX) != -ENOENT);
252+
253+
ida_free(ida, 3);
254+
ida_free(ida, 63);
255+
ida_free(ida, 1023);
256+
ida_free(ida, (1 << 20) - 1);
257+
258+
IDA_BUG_ON(ida, !ida_is_empty(ida));
259+
}
260+
192261
static DEFINE_IDA(ida);
193262

194263
static int ida_checks(void)
@@ -202,6 +271,7 @@ static int ida_checks(void)
202271
ida_check_max(&ida);
203272
ida_check_conv(&ida);
204273
ida_check_bad_free(&ida);
274+
ida_check_find_first(&ida);
205275

206276
printk("IDA: %u of %u tests passed\n", tests_passed, tests_run);
207277
return (tests_run != tests_passed) ? 0 : -EINVAL;

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