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>

diff --git a/include/linux/idr.h b/include/linux/idr.h
index da5f5fa4a3a6ae2be38dec9bb7c5ac73ff8df6e2..718f9b1b91afacb1e51b90393e8f07606da13676 100644 (file)
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -257,6 +257,7 @@ struct ida {
 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
 void ida_free(struct ida *, unsigned int id);
 void ida_destroy(struct ida *ida);
+int ida_find_first_range(struct ida *ida, unsigned int min, unsigned int max);
 
 /**
  * ida_alloc() - Allocate an unused ID.
@@ -328,4 +329,14 @@ static inline bool ida_is_empty(const struct ida *ida)
 {
        return xa_empty(&ida->xa);
 }
+
+static inline bool ida_exists(struct ida *ida, unsigned int id)
+{
+       return ida_find_first_range(ida, id, id) == id;
+}
+
+static inline int ida_find_first(struct ida *ida)
+{
+       return ida_find_first_range(ida, 0, ~0);
+}
 #endif /* __IDR_H__ */

diff --git a/lib/idr.c b/lib/idr.c
index da36054c3ca02058dcfa3338c712ba664b79b13a..e2adc457abb4be7af947dc71f6414036f78128ad 100644 (file)
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -476,6 +476,73 @@ nospc:
 }
 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.

diff --git a/lib/test_ida.c b/lib/test_ida.c
index c80155a1956d27309b17bc8c12b6cca5a025b6f9..63078f8dc13f54d344b2693f4b675473a5f463c6 100644 (file)
--- a/lib/test_ida.c
+++ b/lib/test_ida.c
@@ -189,6 +189,75 @@ static void ida_check_bad_free(struct ida *ida)
        IDA_BUG_ON(ida, !ida_is_empty(ida));
 }
 
+/*
+ * Check ida_find_first_range() and varriants.
+ */
+static void ida_check_find_first(struct ida *ida)
+{
+       /* IDA is empty; all of the below should be not exist */
+       IDA_BUG_ON(ida, ida_exists(ida, 0));
+       IDA_BUG_ON(ida, ida_exists(ida, 3));
+       IDA_BUG_ON(ida, ida_exists(ida, 63));
+       IDA_BUG_ON(ida, ida_exists(ida, 1023));
+       IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+       /* IDA contains a single value entry */
+       IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3);
+       IDA_BUG_ON(ida, ida_exists(ida, 0));
+       IDA_BUG_ON(ida, !ida_exists(ida, 3));
+       IDA_BUG_ON(ida, ida_exists(ida, 63));
+       IDA_BUG_ON(ida, ida_exists(ida, 1023));
+       IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+       IDA_BUG_ON(ida, ida_alloc_min(ida, 63, GFP_KERNEL) != 63);
+       IDA_BUG_ON(ida, ida_exists(ida, 0));
+       IDA_BUG_ON(ida, !ida_exists(ida, 3));
+       IDA_BUG_ON(ida, !ida_exists(ida, 63));
+       IDA_BUG_ON(ida, ida_exists(ida, 1023));
+       IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+       /* IDA contains a single bitmap */
+       IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023);
+       IDA_BUG_ON(ida, ida_exists(ida, 0));
+       IDA_BUG_ON(ida, !ida_exists(ida, 3));
+       IDA_BUG_ON(ida, !ida_exists(ida, 63));
+       IDA_BUG_ON(ida, !ida_exists(ida, 1023));
+       IDA_BUG_ON(ida, ida_exists(ida, (1 << 20) - 1));
+
+       /* IDA contains a tree */
+       IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1);
+       IDA_BUG_ON(ida, ida_exists(ida, 0));
+       IDA_BUG_ON(ida, !ida_exists(ida, 3));
+       IDA_BUG_ON(ida, !ida_exists(ida, 63));
+       IDA_BUG_ON(ida, !ida_exists(ida, 1023));
+       IDA_BUG_ON(ida, !ida_exists(ida, (1 << 20) - 1));
+
+       /* Now try to find first */
+       IDA_BUG_ON(ida, ida_find_first(ida) != 3);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, -1, 2) != -EINVAL);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 2) != -ENOENT); // no used ID
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 0, 3) != 3);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 1, 3) != 3);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 3, 3) != 3);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 2, 4) != 3);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 3) != -ENOENT); // min > max, fail
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 60) != -ENOENT); // no used ID
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 4, 64) != 63);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 63, 63) != 63);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 64, 1026) != 1023);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, 1023) != 1023);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 1023, (1 << 20) - 1) != 1023);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, 1024, (1 << 20) - 1) != (1 << 20) - 1);
+       IDA_BUG_ON(ida, ida_find_first_range(ida, (1 << 20), INT_MAX) != -ENOENT);
+
+       ida_free(ida, 3);
+       ida_free(ida, 63);
+       ida_free(ida, 1023);
+       ida_free(ida, (1 << 20) - 1);
+
+       IDA_BUG_ON(ida, !ida_is_empty(ida));
+}
+
 static DEFINE_IDA(ida);
 
 static int ida_checks(void)
@@ -202,6 +271,7 @@ static int ida_checks(void)
        ida_check_max(&ida);
        ida_check_conv(&ida);
        ida_check_bad_free(&ida);
+       ida_check_find_first(&ida);
 
        printk("IDA: %u of %u tests passed\n", tests_passed, tests_run);
        return (tests_run != tests_passed) ? 0 : -EINVAL;