Merge branch 'ida-4.19' of git://git.infradead.org/users/willy/linux-dax

Pull IDA updates from Matthew Wilcox:
 "A better IDA API:

      id = ida_alloc(ida, GFP_xxx);
      ida_free(ida, id);

  rather than the cumbersome ida_simple_get(), ida_simple_remove().

  The new IDA API is similar to ida_simple_get() but better named.  The
  internal restructuring of the IDA code removes the bitmap
  preallocation nonsense.

  I hope the net -200 lines of code is convincing"

* 'ida-4.19' of git://git.infradead.org/users/willy/linux-dax: (29 commits)
  ida: Change ida_get_new_above to return the id
  ida: Remove old API
  test_ida: check_ida_destroy and check_ida_alloc
  test_ida: Convert check_ida_conv to new API
  test_ida: Move ida_check_max
  test_ida: Move ida_check_leaf
  idr-test: Convert ida_check_nomem to new API
  ida: Start new test_ida module
  target/iscsi: Allocate session IDs from an IDA
  iscsi target: fix session creation failure handling
  drm/vmwgfx: Convert to new IDA API
  dmaengine: Convert to new IDA API
  ppc: Convert vas ID allocation to new IDA API
  media: Convert entity ID allocation to new IDA API
  ppc: Convert mmu context allocation to new IDA API
  Convert net_namespace to new IDA API
  cb710: Convert to new IDA API
  rsxx: Convert to new IDA API
  osd: Convert to new IDA API
  sd: Convert to new IDA API
  ...

5 files changed, 238 insertions, 109 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 3589765141a8..613316724c6a 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1833,6 +1833,9 @@ config TEST_HASH
 	  This is intended to help people writing architecture-specific
 	  optimized versions.  If unsure, say N.
 
+config TEST_IDA
+	tristate "Perform selftest on IDA functions"
+
 config TEST_PARMAN
 	tristate "Perform selftest on priority array manager"
 	depends on PARMAN
diff --git a/lib/Makefile b/lib/Makefile
index 9baefb6cb1a1..ca3f7ebb900d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_TEST_BPF) += test_bpf.o
 obj-$(CONFIG_TEST_FIRMWARE) += test_firmware.o
 obj-$(CONFIG_TEST_SYSCTL) += test_sysctl.o
 obj-$(CONFIG_TEST_HASH) += test_hash.o test_siphash.o
+obj-$(CONFIG_TEST_IDA) += test_ida.o
 obj-$(CONFIG_TEST_KASAN) += test_kasan.o
 CFLAGS_test_kasan.o += -fno-builtin
 obj-$(CONFIG_TEST_UBSAN) += test_ubsan.o
diff --git a/lib/idr.c b/lib/idr.c
index ed9c169c12bd..fab2fd5bc326 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -317,18 +317,12 @@ EXPORT_SYMBOL(idr_replace);
  * bit per ID, and so is more space efficient than an IDR.  To use an IDA,
  * define it using DEFINE_IDA() (or embed a &struct ida in a data structure,
  * then initialise it using ida_init()).  To allocate a new ID, call
- * ida_simple_get().  To free an ID, call ida_simple_remove().
+ * ida_alloc(), ida_alloc_min(), ida_alloc_max() or ida_alloc_range().
+ * To free an ID, call ida_free().
  *
- * If you have more complex locking requirements, use a loop around
- * ida_pre_get() and ida_get_new() to allocate a new ID.  Then use
- * ida_remove() to free an ID.  You must make sure that ida_get_new() and
- * ida_remove() cannot be called at the same time as each other for the
- * same IDA.
- *
- * You can also use ida_get_new_above() if you need an ID to be allocated
- * above a particular number.  ida_destroy() can be used to dispose of an
- * IDA without needing to free the individual IDs in it.  You can use
- * ida_is_empty() to find out whether the IDA has any IDs currently allocated.
+ * ida_destroy() can be used to dispose of an IDA without needing to
+ * free the individual IDs in it.  You can use ida_is_empty() to find
+ * out whether the IDA has any IDs currently allocated.
  *
  * IDs are currently limited to the range [0-INT_MAX].  If this is an awkward
  * limitation, it should be quite straightforward to raise the maximum.
@@ -369,25 +363,7 @@ EXPORT_SYMBOL(idr_replace);
 
 #define IDA_MAX (0x80000000U / IDA_BITMAP_BITS - 1)
 
-/**
- * ida_get_new_above - allocate new ID above or equal to a start id
- * @ida: ida handle
- * @start: id to start search at
- * @id: pointer to the allocated handle
- *
- * Allocate new ID above or equal to @start.  It should be called
- * with any required locks to ensure that concurrent calls to
- * ida_get_new_above() / ida_get_new() / ida_remove() are not allowed.
- * Consider using ida_simple_get() if you do not have complex locking
- * requirements.
- *
- * If memory is required, it will return %-EAGAIN, you should unlock
- * and go back to the ida_pre_get() call.  If the ida is full, it will
- * return %-ENOSPC.  On success, it will return 0.
- *
- * @id returns a value in the range @start ... %0x7fffffff.
- */
-int ida_get_new_above(struct ida *ida, int start, int *id)
+static int ida_get_new_above(struct ida *ida, int start)
 {
 	struct radix_tree_root *root = &ida->ida_rt;
 	void __rcu **slot;
@@ -426,8 +402,8 @@ int ida_get_new_above(struct ida *ida, int start, int *id)
 			if (ebit < BITS_PER_LONG) {
 				tmp |= 1UL << ebit;
 				rcu_assign_pointer(*slot, (void *)tmp);
-				*id = new + ebit - RADIX_TREE_EXCEPTIONAL_SHIFT;
-				return 0;
+				return new + ebit -
+					RADIX_TREE_EXCEPTIONAL_SHIFT;
 			}
 			bitmap = this_cpu_xchg(ida_bitmap, NULL);
 			if (!bitmap)
@@ -458,8 +434,7 @@ int ida_get_new_above(struct ida *ida, int start, int *id)
 						RADIX_TREE_EXCEPTIONAL_ENTRY);
 				radix_tree_iter_replace(root, &iter, slot,
 						bitmap);
-				*id = new;
-				return 0;
+				return new;
 			}
 			bitmap = this_cpu_xchg(ida_bitmap, NULL);
 			if (!bitmap)
@@ -468,20 +443,11 @@ int ida_get_new_above(struct ida *ida, int start, int *id)
 			radix_tree_iter_replace(root, &iter, slot, bitmap);
 		}
 
-		*id = new;
-		return 0;
+		return new;
 	}
 }
-EXPORT_SYMBOL(ida_get_new_above);
 
-/**
- * ida_remove - Free the given ID
- * @ida: ida handle
- * @id: ID to free
- *
- * This function should not be called at the same time as ida_get_new_above().
- */
-void ida_remove(struct ida *ida, int id)
+static void ida_remove(struct ida *ida, int id)
 {
 	unsigned long index = id / IDA_BITMAP_BITS;
 	unsigned offset = id % IDA_BITMAP_BITS;
@@ -518,99 +484,90 @@ void ida_remove(struct ida *ida, int id)
 	}
 	return;
  err:
-	WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
+	WARN(1, "ida_free called for id=%d which is not allocated.\n", id);
 }
-EXPORT_SYMBOL(ida_remove);
 
 /**
- * ida_destroy - Free the contents of an ida
- * @ida: ida handle
+ * ida_destroy() - Free all IDs.
+ * @ida: IDA handle.
+ *
+ * Calling this function frees all IDs and releases all resources used
+ * by an IDA.  When this call returns, the IDA is empty and can be reused
+ * or freed.  If the IDA is already empty, there is no need to call this
+ * function.
  *
- * Calling this function releases all resources associated with an IDA.  When
- * this call returns, the IDA is empty and can be reused or freed.  The caller
- * should not allow ida_remove() or ida_get_new_above() to be called at the
- * same time.
+ * Context: Any context.
  */
 void ida_destroy(struct ida *ida)
 {
+	unsigned long flags;
 	struct radix_tree_iter iter;
 	void __rcu **slot;
 
+	xa_lock_irqsave(&ida->ida_rt, flags);
 	radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) {
 		struct ida_bitmap *bitmap = rcu_dereference_raw(*slot);
 		if (!radix_tree_exception(bitmap))
 			kfree(bitmap);
 		radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
 	}
+	xa_unlock_irqrestore(&ida->ida_rt, flags);
 }
 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.
+ * ida_alloc_range() - Allocate an unused ID.
+ * @ida: IDA handle.
+ * @min: Lowest ID to allocate.
+ * @max: Highest ID to allocate.
+ * @gfp: Memory allocation flags.
  *
- * Compared to ida_get_new_above() this function does its own locking, and
- * should be used unless there are special requirements.
+ * Allocate an ID between @min and @max, inclusive.  The allocated ID will
+ * not exceed %INT_MAX, even if @max is larger.
  *
- * Use ida_simple_remove() to get rid of an id.
+ * Context: Any context.
+ * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
+ * or %-ENOSPC if there are no free IDs.
  */
-int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
-		   gfp_t gfp_mask)
+int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
+			gfp_t gfp)
 {
-	int ret, id;
-	unsigned int max;
+	int id = 0;
 	unsigned long flags;
 
-	BUG_ON((int)start < 0);
-	BUG_ON((int)end < 0);
+	if ((int)min < 0)
+		return -ENOSPC;
 
-	if (end == 0)
-		max = 0x80000000;
-	else {
-		BUG_ON(end < start);
-		max = end - 1;
-	}
+	if ((int)max < 0)
+		max = INT_MAX;
 
 again:
-	if (!ida_pre_get(ida, gfp_mask))
-		return -ENOMEM;
-
 	xa_lock_irqsave(&ida->ida_rt, flags);
-	ret = ida_get_new_above(ida, start, &id);
-	if (!ret) {
-		if (id > max) {
-			ida_remove(ida, id);
-			ret = -ENOSPC;
-		} else {
-			ret = id;
-		}
+	id = ida_get_new_above(ida, min);
+	if (id > (int)max) {
+		ida_remove(ida, id);
+		id = -ENOSPC;
 	}
 	xa_unlock_irqrestore(&ida->ida_rt, flags);
 
-	if (unlikely(ret == -EAGAIN))
+	if (unlikely(id == -EAGAIN)) {
+		if (!ida_pre_get(ida, gfp))
+			return -ENOMEM;
 		goto again;
+	}
 
-	return ret;
+	return id;
 }
-EXPORT_SYMBOL(ida_simple_get);
+EXPORT_SYMBOL(ida_alloc_range);
 
 /**
- * ida_simple_remove - remove an allocated id.
- * @ida: the (initialized) ida.
- * @id: the id returned by ida_simple_get.
- *
- * Use to release an id allocated with ida_simple_get().
+ * ida_free() - Release an allocated ID.
+ * @ida: IDA handle.
+ * @id: Previously allocated ID.
  *
- * Compared to ida_remove() this function does its own locking, and should be
- * used unless there are special requirements.
+ * Context: Any context.
  */
-void ida_simple_remove(struct ida *ida, unsigned int id)
+void ida_free(struct ida *ida, unsigned int id)
 {
 	unsigned long flags;
 
@@ -619,4 +576,4 @@ void ida_simple_remove(struct ida *ida, unsigned int id)
 	ida_remove(ida, id);
 	xa_unlock_irqrestore(&ida->ida_rt, flags);
 }
-EXPORT_SYMBOL(ida_simple_remove);
+EXPORT_SYMBOL(ida_free);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index a9e41aed6de4..bc03ecc4dfd2 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -120,7 +120,7 @@ bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
 static inline unsigned long
 get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
 {
-	return slot - parent->slots;
+	return parent ? slot - parent->slots : 0;
 }
 
 static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
@@ -2106,14 +2106,6 @@ void idr_preload(gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(idr_preload);
 
-/**
- * ida_pre_get - reserve resources for ida allocation
- * @ida: ida handle
- * @gfp: memory allocation flags
- *
- * This function should be called before calling ida_get_new_above().  If it
- * is unable to allocate memory, it will return %0.  On success, it returns %1.
- */
 int ida_pre_get(struct ida *ida, gfp_t gfp)
 {
 	/*
@@ -2134,7 +2126,6 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
 
 	return 1;
 }
-EXPORT_SYMBOL(ida_pre_get);
 
 void __rcu **idr_get_free(struct radix_tree_root *root,
 			      struct radix_tree_iter *iter, gfp_t gfp,
diff --git a/lib/test_ida.c b/lib/test_ida.c
new file mode 100644
index 000000000000..2d1637d8136b
--- /dev/null
+++ b/lib/test_ida.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * test_ida.c: Test the IDA API
+ * Copyright (c) 2016-2018 Microsoft Corporation
+ * Copyright (c) 2018 Oracle Corporation
+ * Author: Matthew Wilcox <willy@infradead.org>
+ */
+
+#include <linux/idr.h>
+#include <linux/module.h>
+
+static unsigned int tests_run;
+static unsigned int tests_passed;
+
+#ifdef __KERNEL__
+void ida_dump(struct ida *ida) { }
+#endif
+#define IDA_BUG_ON(ida, x) do {						\
+	tests_run++;							\
+	if (x) {							\
+		ida_dump(ida);						\
+		dump_stack();						\
+	} else {							\
+		tests_passed++;						\
+	}								\
+} while (0)
+
+/*
+ * Straightforward checks that allocating and freeing IDs work.
+ */
+static void ida_check_alloc(struct ida *ida)
+{
+	int i, id;
+
+	for (i = 0; i < 10000; i++)
+		IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != i);
+
+	ida_free(ida, 20);
+	ida_free(ida, 21);
+	for (i = 0; i < 3; i++) {
+		id = ida_alloc(ida, GFP_KERNEL);
+		IDA_BUG_ON(ida, id < 0);
+		if (i == 2)
+			IDA_BUG_ON(ida, id != 10000);
+	}
+
+	for (i = 0; i < 5000; i++)
+		ida_free(ida, i);
+
+	IDA_BUG_ON(ida, ida_alloc_min(ida, 5000, GFP_KERNEL) != 10001);
+	ida_destroy(ida);
+
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+}
+
+/* Destroy an IDA with a single entry at @base */
+static void ida_check_destroy_1(struct ida *ida, unsigned int base)
+{
+	IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) != base);
+	IDA_BUG_ON(ida, ida_is_empty(ida));
+	ida_destroy(ida);
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+}
+
+/* Check that ida_destroy and ida_is_empty work */
+static void ida_check_destroy(struct ida *ida)
+{
+	/* Destroy an already-empty IDA */
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+	ida_destroy(ida);
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+
+	ida_check_destroy_1(ida, 0);
+	ida_check_destroy_1(ida, 1);
+	ida_check_destroy_1(ida, 1023);
+	ida_check_destroy_1(ida, 1024);
+	ida_check_destroy_1(ida, 12345678);
+}
+
+/*
+ * Check what happens when we fill a leaf and then delete it.  This may
+ * discover mishandling of IDR_FREE.
+ */
+static void ida_check_leaf(struct ida *ida, unsigned int base)
+{
+	unsigned long i;
+
+	for (i = 0; i < IDA_BITMAP_BITS; i++) {
+		IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) !=
+				base + i);
+	}
+
+	ida_destroy(ida);
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+
+	IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != 0);
+	IDA_BUG_ON(ida, ida_is_empty(ida));
+	ida_free(ida, 0);
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+}
+
+/*
+ * Check allocations up to and slightly above the maximum allowed (2^31-1) ID.
+ * Allocating up to 2^31-1 should succeed, and then allocating the next one
+ * should fail.
+ */
+static void ida_check_max(struct ida *ida)
+{
+	unsigned long i, j;
+
+	for (j = 1; j < 65537; j *= 2) {
+		unsigned long base = (1UL << 31) - j;
+		for (i = 0; i < j; i++) {
+			IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) !=
+					base + i);
+		}
+		IDA_BUG_ON(ida, ida_alloc_min(ida, base, GFP_KERNEL) !=
+				-ENOSPC);
+		ida_destroy(ida);
+		IDA_BUG_ON(ida, !ida_is_empty(ida));
+	}
+}
+
+/*
+ * Check handling of conversions between exceptional entries and full bitmaps.
+ */
+static void ida_check_conv(struct ida *ida)
+{
+	unsigned long i;
+
+	for (i = 0; i < IDA_BITMAP_BITS * 2; i += IDA_BITMAP_BITS) {
+		IDA_BUG_ON(ida, ida_alloc_min(ida, i + 1, GFP_KERNEL) != i + 1);
+		IDA_BUG_ON(ida, ida_alloc_min(ida, i + BITS_PER_LONG,
+					GFP_KERNEL) != i + BITS_PER_LONG);
+		ida_free(ida, i + 1);
+		ida_free(ida, i + BITS_PER_LONG);
+		IDA_BUG_ON(ida, !ida_is_empty(ida));
+	}
+
+	for (i = 0; i < IDA_BITMAP_BITS * 2; i++)
+		IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != i);
+	for (i = IDA_BITMAP_BITS * 2; i > 0; i--)
+		ida_free(ida, i - 1);
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+
+	for (i = 0; i < IDA_BITMAP_BITS + BITS_PER_LONG - 4; i++)
+		IDA_BUG_ON(ida, ida_alloc(ida, GFP_KERNEL) != i);
+	for (i = IDA_BITMAP_BITS + BITS_PER_LONG - 4; i > 0; i--)
+		ida_free(ida, i - 1);
+	IDA_BUG_ON(ida, !ida_is_empty(ida));
+}
+
+static int ida_checks(void)
+{
+	DEFINE_IDA(ida);
+
+	IDA_BUG_ON(&ida, !ida_is_empty(&ida));
+	ida_check_alloc(&ida);
+	ida_check_destroy(&ida);
+	ida_check_leaf(&ida, 0);
+	ida_check_leaf(&ida, 1024);
+	ida_check_leaf(&ida, 1024 * 64);
+	ida_check_max(&ida);
+	ida_check_conv(&ida);
+
+	printk("IDA: %u of %u tests passed\n", tests_passed, tests_run);
+	return (tests_run != tests_passed) ? 0 : -EINVAL;
+}
+
+static void ida_exit(void)
+{
+}
+
+module_init(ida_checks);
+module_exit(ida_exit);
+MODULE_AUTHOR("Matthew Wilcox <willy@infradead.org>");
+MODULE_LICENSE("GPL");