Merge branch 'idr-2018-02-06' of git://git.infradead.org/users/willy/linux-dax

Pull idr updates from Matthew Wilcox:

 - test-suite improvements

 - replace the extended API by improving the normal API

 - performance improvement for IDRs which are 1-based rather than
   0-based

 - add documentation

* 'idr-2018-02-06' of git://git.infradead.org/users/willy/linux-dax:
  idr: Add documentation
  idr: Make 1-based IDRs more efficient
  idr: Warn if old iterators see large IDs
  idr: Rename idr_for_each_entry_ext
  idr: Remove idr_alloc_ext
  cls_u32: Convert to idr_alloc_u32
  cls_u32: Reinstate cyclic allocation
  cls_flower: Convert to idr_alloc_u32
  cls_bpf: Convert to use idr_alloc_u32
  cls_basic: Convert to use idr_alloc_u32
  cls_api: Convert to idr_alloc_u32
  net sched actions: Convert to use idr_alloc_u32
  idr: Add idr_alloc_u32 helper
  idr: Delete idr_find_ext function
  idr: Delete idr_replace_ext function
  idr: Delete idr_remove_ext function
  IDR test suite: Check handling negative end correctly
  idr test suite: Fix ida_test_random()
  radix tree test suite: Remove ARRAY_SIZE

Author: torvalds

Documentation/core-api/idr.rst

@@ -0,0 +1,79 @@
+.. SPDX-License-Identifier: CC-BY-SA-4.0
+
+=============
+ID Allocation
+=============
+
+:Author: Matthew Wilcox
+
+Overview
+========
+
+A common problem to solve is allocating identifiers (IDs); generally
+small numbers which identify a thing.  Examples include file descriptors,
+process IDs, packet identifiers in networking protocols, SCSI tags
+and device instance numbers.  The IDR and the IDA provide a reasonable
+solution to the problem to avoid everybody inventing their own.  The IDR
+provides the ability to map an ID to a pointer, while the IDA provides
+only ID allocation, and as a result is much more memory-efficient.
+
+IDR usage
+=========
+
+Start by initialising an IDR, either with :c:func:`DEFINE_IDR`
+for statically allocated IDRs or :c:func:`idr_init` for dynamically
+allocated IDRs.
+
+You can call :c:func:`idr_alloc` to allocate an unused ID.  Look up
+the pointer you associated with the ID by calling :c:func:`idr_find`
+and free the ID by calling :c:func:`idr_remove`.
+
+If you need to change the pointer associated with an ID, you can call
+:c:func:`idr_replace`.  One common reason to do this is to reserve an
+ID by passing a ``NULL`` pointer to the allocation function; initialise the
+object with the reserved ID and finally insert the initialised object
+into the IDR.
+
+Some users need to allocate IDs larger than ``INT_MAX``.  So far all of
+these users have been content with a ``UINT_MAX`` limit, and they use
+:c:func:`idr_alloc_u32`.  If you need IDs that will not fit in a u32,
+we will work with you to address your needs.
+
+If you need to allocate IDs sequentially, you can use
+:c:func:`idr_alloc_cyclic`.  The IDR becomes less efficient when dealing
+with larger IDs, so using this function comes at a slight cost.
+
+To perform an action on all pointers used by the IDR, you can
+either use the callback-based :c:func:`idr_for_each` or the
+iterator-style :c:func:`idr_for_each_entry`.  You may need to use
+:c:func:`idr_for_each_entry_continue` to continue an iteration.  You can
+also use :c:func:`idr_get_next` if the iterator doesn't fit your needs.
+
+When you have finished using an IDR, you can call :c:func:`idr_destroy`
+to release the memory used by the IDR.  This will not free the objects
+pointed to from the IDR; if you want to do that, use one of the iterators
+to do it.
+
+You can use :c:func:`idr_is_empty` to find out whether there are any
+IDs currently allocated.
+
+If you need to take a lock while allocating a new ID from the IDR,
+you may need to pass a restrictive set of GFP flags, which can lead
+to the IDR being unable to allocate memory.  To work around this,
+you can call :c:func:`idr_preload` before taking the lock, and then
+:c:func:`idr_preload_end` after the allocation.
+
+.. kernel-doc:: include/linux/idr.h
+   :doc: idr sync
+
+IDA usage
+=========
+
+.. kernel-doc:: lib/idr.c
+   :doc: IDA description
+
+Functions and structures
+========================
+
+.. kernel-doc:: include/linux/idr.h
+.. kernel-doc:: lib/idr.c

Documentation/core-api/index.rst

@@ -16,6 +16,7 @@ Core utilities
    atomic_ops
    refcount-vs-atomic
    cpu_hotplug
+   idr
    local_ops
    workqueue
    genericirq

Documentation/core-api/kernel-api.rst

@@ -103,18 +103,6 @@ CRC Functions
 .. kernel-doc:: lib/crc-itu-t.c
    :export:
 
-idr/ida Functions
------------------
-
-.. kernel-doc:: include/linux/idr.h
-   :doc: idr sync
-
-.. kernel-doc:: lib/idr.c
-   :doc: IDA description
-
-.. kernel-doc:: lib/idr.c
-   :export:
-
 Math Functions in Linux
 =======================
 

include/linux/idr.h

@@ -15,10 +15,10 @@
 #include <linux/radix-tree.h>
 #include <linux/gfp.h>
 #include <linux/percpu.h>
-#include <linux/bug.h>
 
 struct idr {
 	struct radix_tree_root	idr_rt;
+	unsigned int		idr_base;
 	unsigned int		idr_next;
 };
 
@@ -31,10 +31,26 @@ struct idr {
 /* Set the IDR flag and the IDR_FREE tag */
 #define IDR_RT_MARKER		((__force gfp_t)(3 << __GFP_BITS_SHIFT))
 
-#define IDR_INIT							\
-{									\
-	.idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER)			\
+#define IDR_INIT_BASE(base) {						\
+	.idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER),			\
+	.idr_base = (base),						\
+	.idr_next = 0,							\
 }
+
+/**
+ * IDR_INIT() - Initialise an IDR.
+ *
+ * A freshly-initialised IDR contains no IDs.
+ */
+#define IDR_INIT	IDR_INIT_BASE(0)
+
+/**
+ * DEFINE_IDR() - Define a statically-allocated IDR
+ * @name: Name of IDR
+ *
+ * An IDR defined using this macro is ready for use with no additional
+ * initialisation required.  It contains no IDs.
+ */
 #define DEFINE_IDR(name)	struct idr name = IDR_INIT
 
 /**
@@ -82,80 +98,52 @@ static inline void idr_set_cursor(struct idr *idr, unsigned int val)
 
 void idr_preload(gfp_t gfp_mask);
 
-int idr_alloc_cmn(struct idr *idr, void *ptr, unsigned long *index,
-		  unsigned long start, unsigned long end, gfp_t gfp,
-		  bool ext);
-
-/**
- * idr_alloc - allocate an id
- * @idr: idr handle
- * @ptr: pointer to be associated with the new id
- * @start: the minimum id (inclusive)
- * @end: the maximum id (exclusive)
- * @gfp: memory allocation flags
- *
- * Allocates an unused ID in the range [start, end).  Returns -ENOSPC
- * if there are no unused IDs in that range.
- *
- * Note that @end is treated as max when <= 0.  This is to always allow
- * using @start + N as @end as long as N is inside integer range.
- *
- * Simultaneous modifications to the @idr are not allowed and should be
- * prevented by the user, usually with a lock.  idr_alloc() may be called
- * concurrently with read-only accesses to the @idr, such as idr_find() and
- * idr_for_each_entry().
- */
-static inline int idr_alloc(struct idr *idr, void *ptr,
-			    int start, int end, gfp_t gfp)
-{
-	unsigned long id;
-	int ret;
-
-	if (WARN_ON_ONCE(start < 0))
-		return -EINVAL;
-
-	ret = idr_alloc_cmn(idr, ptr, &id, start, end, gfp, false);
-
-	if (ret)
-		return ret;
-
-	return id;
-}
-
-static inline int idr_alloc_ext(struct idr *idr, void *ptr,
-				unsigned long *index,
-				unsigned long start,
-				unsigned long end,
-				gfp_t gfp)
-{
-	return idr_alloc_cmn(idr, ptr, index, start, end, gfp, true);
-}
-
-int idr_alloc_cyclic(struct idr *, void *entry, int start, int end, gfp_t);
+int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t);
+int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id,
+				unsigned long max, gfp_t);
+int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t);
+void *idr_remove(struct idr *, unsigned long id);
+void *idr_find(const struct idr *, unsigned long id);
 int idr_for_each(const struct idr *,
 		 int (*fn)(int id, void *p, void *data), void *data);
 void *idr_get_next(struct idr *, int *nextid);
-void *idr_get_next_ext(struct idr *idr, unsigned long *nextid);
-void *idr_replace(struct idr *, void *, int id);
-void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long id);
+void *idr_get_next_ul(struct idr *, unsigned long *nextid);
+void *idr_replace(struct idr *, void *, unsigned long id);
 void idr_destroy(struct idr *);
 
-static inline void *idr_remove_ext(struct idr *idr, unsigned long id)
-{
-	return radix_tree_delete_item(&idr->idr_rt, id, NULL);
-}
-
-static inline void *idr_remove(struct idr *idr, int id)
+/**
+ * idr_init_base() - Initialise an IDR.
+ * @idr: IDR handle.
+ * @base: The base value for the IDR.
+ *
+ * This variation of idr_init() creates an IDR which will allocate IDs
+ * starting at %base.
+ */
+static inline void idr_init_base(struct idr *idr, int base)
 {
-	return idr_remove_ext(idr, id);
+	INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
+	idr->idr_base = base;
+	idr->idr_next = 0;
 }
 
+/**
+ * idr_init() - Initialise an IDR.
+ * @idr: IDR handle.
+ *
+ * Initialise a dynamically allocated IDR.  To initialise a
+ * statically allocated IDR, use DEFINE_IDR().
+ */
 static inline void idr_init(struct idr *idr)
 {
-	INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
-	idr->idr_next = 0;
+	idr_init_base(idr, 0);
 }
 
+/**
+ * idr_is_empty() - Are there any IDs allocated?
+ * @idr: IDR handle.
+ *
+ * Return: %true if any IDs have been allocated from this IDR.
+ */
 static inline bool idr_is_empty(const struct idr *idr)
 {
 	return radix_tree_empty(&idr->idr_rt) &&
@@ -174,50 +162,38 @@ static inline void idr_preload_end(void)
 }
 
 /**
- * idr_find - return pointer for given id
- * @idr: idr handle
- * @id: lookup key
- *
- * Return the pointer given the id it has been registered with.  A %NULL
- * return indicates that @id is not valid or you passed %NULL in
- * idr_get_new().
+ * idr_for_each_entry() - Iterate over an IDR's elements of a given type.
+ * @idr: IDR handle.
+ * @entry: The type * to use as cursor
+ * @id: Entry ID.
  *
- * This function can be called under rcu_read_lock(), given that the leaf
- * pointers lifetimes are correctly managed.
+ * @entry and @id do not need to be initialized before the loop, and
+ * after normal termination @entry is left with the value NULL.  This
+ * is convenient for a "not found" value.
  */
-static inline void *idr_find_ext(const struct idr *idr, unsigned long id)
-{
-	return radix_tree_lookup(&idr->idr_rt, id);
-}
-
-static inline void *idr_find(const struct idr *idr, int id)
-{
-	return idr_find_ext(idr, id);
-}
+#define idr_for_each_entry(idr, entry, id)			\
+	for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id)
 
 /**
- * idr_for_each_entry - iterate over an idr's elements of a given type
- * @idr:     idr handle
- * @entry:   the type * to use as cursor
- * @id:      id entry's key
+ * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type.
+ * @idr: IDR handle.
+ * @entry: The type * to use as cursor.
+ * @id: Entry ID.
  *
  * @entry and @id do not need to be initialized before the loop, and
- * after normal terminatinon @entry is left with the value NULL.  This
+ * after normal termination @entry is left with the value NULL.  This
  * is convenient for a "not found" value.
  */
-#define idr_for_each_entry(idr, entry, id)			\
-	for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; ++id)
-#define idr_for_each_entry_ext(idr, entry, id)			\
-	for (id = 0; ((entry) = idr_get_next_ext(idr, &(id))) != NULL; ++id)
+#define idr_for_each_entry_ul(idr, entry, id)			\
+	for (id = 0; ((entry) = idr_get_next_ul(idr, &(id))) != NULL; ++id)
 
 /**
- * idr_for_each_entry_continue - continue iteration over an idr's elements of a given type
- * @idr:     idr handle
- * @entry:   the type * to use as cursor
- * @id:      id entry's key
+ * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type
+ * @idr: IDR handle.
+ * @entry: The type * to use as a cursor.
+ * @id: Entry ID.
  *
- * Continue to iterate over list of given type, continuing after
- * the current position.
+ * Continue to iterate over entries, continuing after the current position.
  */
 #define idr_for_each_entry_continue(idr, entry, id)			\
 	for ((entry) = idr_get_next((idr), &(id));			\

include/linux/radix-tree.h

@@ -356,24 +356,9 @@ int radix_tree_split(struct radix_tree_root *, unsigned long index,
 int radix_tree_join(struct radix_tree_root *, unsigned long index,
 			unsigned new_order, void *);
 
-void __rcu **idr_get_free_cmn(struct radix_tree_root *root,
+void __rcu **idr_get_free(struct radix_tree_root *root,
 			      struct radix_tree_iter *iter, gfp_t gfp,
 			      unsigned long max);
-static inline void __rcu **idr_get_free(struct radix_tree_root *root,
-					struct radix_tree_iter *iter,
-					gfp_t gfp,
-					int end)
-{
-	return idr_get_free_cmn(root, iter, gfp, end > 0 ? end - 1 : INT_MAX);
-}
-
-static inline void __rcu **idr_get_free_ext(struct radix_tree_root *root,
-					    struct radix_tree_iter *iter,
-					    gfp_t gfp,
-					    unsigned long end)
-{
-	return idr_get_free_cmn(root, iter, gfp, end - 1);
-}
 
 enum {
 	RADIX_TREE_ITER_TAG_MASK = 0x0f,	/* tag index in lower nybble */