From 7fe6b987166b901efc5c6fce5fe853c9ebb835be Mon Sep 17 00:00:00 2001 From: Yi Liu Date: Fri, 21 Mar 2025 11:01:39 -0700 Subject: 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) Suggested-by: Jason Gunthorpe Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Acked-by: Matthew Wilcox (Oracle) Tested-by: Nicolin Chen Signed-off-by: Yi Liu Signed-off-by: Jason Gunthorpe --- lib/idr.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) (limited to 'lib/idr.c') diff --git a/lib/idr.c b/lib/idr.c index da36054c3ca020..e2adc457abb4be 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -476,6 +476,73 @@ int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max, } EXPORT_SYMBOL(ida_alloc_range); +/** + * ida_find_first_range - Get the lowest used ID. + * @ida: IDA handle. + * @min: Lowest ID to get. + * @max: Highest ID to get. + * + * Get the lowest used ID between @min and @max, inclusive. The returned + * ID will not exceed %INT_MAX, even if @max is larger. + * + * Context: Any context. Takes and releases the xa_lock. + * Return: The lowest used ID, or errno if no used ID is found. + */ +int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max) +{ + unsigned long index = min / IDA_BITMAP_BITS; + unsigned int offset = min % IDA_BITMAP_BITS; + unsigned long *addr, size, bit; + unsigned long tmp = 0; + unsigned long flags; + void *entry; + int ret; + + if ((int)min < 0) + return -EINVAL; + if ((int)max < 0) + max = INT_MAX; + + xa_lock_irqsave(&ida->xa, flags); + + entry = xa_find(&ida->xa, &index, max / IDA_BITMAP_BITS, XA_PRESENT); + if (!entry) { + ret = -ENOENT; + goto err_unlock; + } + + if (index > min / IDA_BITMAP_BITS) + offset = 0; + if (index * IDA_BITMAP_BITS + offset > max) { + ret = -ENOENT; + goto err_unlock; + } + + if (xa_is_value(entry)) { + tmp = xa_to_value(entry); + addr = &tmp; + size = BITS_PER_XA_VALUE; + } else { + addr = ((struct ida_bitmap *)entry)->bitmap; + size = IDA_BITMAP_BITS; + } + + bit = find_next_bit(addr, size, offset); + + xa_unlock_irqrestore(&ida->xa, flags); + + if (bit == size || + index * IDA_BITMAP_BITS + bit > max) + return -ENOENT; + + return index * IDA_BITMAP_BITS + bit; + +err_unlock: + xa_unlock_irqrestore(&ida->xa, flags); + return ret; +} +EXPORT_SYMBOL(ida_find_first_range); + /** * ida_free() - Release an allocated ID. * @ida: IDA handle. -- cgit 1.2.3-korg