Message-ID: <20170911211408.GA26747@bombadil.infradead.org>
Date:   Mon, 11 Sep 2017 14:14:08 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Chris Mi <chrism@...lanox.com>
Cc:     Jiri Pirko <jiri@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>, Tejun Heo <tj@...nel.org>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Rehas Sachdeva <aquannie@...il.com>
Subject: Extended IDR API


I really don't like your new API.  I wish you'd discussed it before
merging it.  Here's my redesign.  Does anybody have a suggestion for
improvement?

We have a lovely new test-suite for the IDR (in tools/testing/radix-tree)
... when adding a new API, it's polite to update the test-suite too.
Do you have any plans to add test cases?

(Compile tested only; I'm at a conference.  Also, I didn't check the
kerneldoc because I don't have Sphinx installed on my laptop.)

>From ff45b2a6806cd0e4177c5a10f26c97999164c10c Mon Sep 17 00:00:00 2001
From: Matthew Wilcox <mawilcox@...rosoft.com>
Date: Mon, 11 Sep 2017 16:16:29 -0400
Subject: [PATCH] idr: Rewrite extended IDR API

 - Rename the API to be 'ul' for unsigned long instead of 'ext'.  This
   fits better with other usage in the Linux kernel.
 - idr_alloc() moves back to being a function instead of inline
 - idr_alloc_ul() takes 'nextid' as an in-out parameter like idr_get_next(),
   instead of having 'index' as an out-only parameter.
 - idr_alloc_ul() needs a __must_check to ensure that users don't look at
   the result without checking whether the function succeeded.
 - idr_alloc_ul() takes 'max' rather than 'end', or it is impossible to
   allocate the ULONG_MAX id.
 - idr_replace() can simply take an unsigned long parameter instead of
   an int.
 - idr_remove() and idr_find() are the same as idr_replace().
 - We don't need separate idr_get_free() and idr_get_free_ext().
 - Add kerneldoc for idr_alloc_ul().

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 include/linux/idr.h        | 75 +++++----------------------------------
 include/linux/radix-tree.h | 17 +--------
 lib/idr.c                  | 88 +++++++++++++++++++++++++++++++++-------------
 lib/radix-tree.c           |  2 +-
 net/sched/act_api.c        | 22 ++++++------
 net/sched/cls_flower.c     | 16 +++++----
 6 files changed, 95 insertions(+), 125 deletions(-)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index 7c3a365f7e12..90faf8279559 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -81,74 +81,22 @@ 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(struct idr *, void *, int start, int end, gfp_t);
+int __must_check idr_alloc_ul(struct idr *, void *, unsigned long *nextid,
+			unsigned long max, gfp_t);
 int idr_alloc_cyclic(struct idr *, void *entry, int start, int end, gfp_t);
 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)
+static inline void *idr_remove(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)
-{
-	return idr_remove_ext(idr, id);
-}
-
 static inline void idr_init(struct idr *idr)
 {
 	INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER);
@@ -184,16 +132,11 @@ static inline void idr_preload_end(void)
  * This function can be called under rcu_read_lock(), given that the leaf
  * pointers lifetimes are correctly managed.
  */
-static inline void *idr_find_ext(const struct idr *idr, unsigned long id)
+static inline void *idr_find(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);
-}
-
 /**
  * idr_for_each_entry - iterate over an idr's elements of a given type
  * @idr:     idr handle
@@ -206,8 +149,8 @@ static inline void *idr_find(const struct idr *idr, int id)
  */
 #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
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 567ebb5eaab0..8275fc2ed0f4 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -358,24 +358,9 @@ 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 */
diff --git a/lib/idr.c b/lib/idr.c
index 082778cf883e..230879a65d99 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -7,9 +7,26 @@
 DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap);
 static DEFINE_SPINLOCK(simple_ida_lock);
 
-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_ul - allocate a large ID
+ * @idr: idr handle
+ * @ptr: pointer to be associated with the new ID
+ * @nextid: Pointer to minimum ID to allocate
+ * @max: the maximum ID (inclusive)
+ * @gfp: memory allocation flags
+ *
+ * Allocates an unused ID in the range [*nextid, end] and stores it in
+ * @nextid.  Note that @max differs from the @end parameter to idr_alloc().
+ *
+ * Simultaneous modifications to the @idr are not allowed and should be
+ * prevented by the user, usually with a lock.  idr_alloc_ul() may be called
+ * concurrently with read-only accesses to the @idr, such as idr_find() and
+ * idr_for_each_entry().
+ *
+ * Return: 0 on success or a negative errno on failure (ENOMEM or ENOSPC)
+ */
+int idr_alloc_ul(struct idr *idr, void *ptr, unsigned long *nextid,
+			unsigned long max, gfp_t gfp)
 {
 	struct radix_tree_iter iter;
 	void __rcu **slot;
@@ -17,22 +34,54 @@ int idr_alloc_cmn(struct idr *idr, void *ptr, unsigned long *index,
 	if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
 		return -EINVAL;
 
-	radix_tree_iter_init(&iter, start);
-	if (ext)
-		slot = idr_get_free_ext(&idr->idr_rt, &iter, gfp, end);
-	else
-		slot = idr_get_free(&idr->idr_rt, &iter, gfp, end);
+	radix_tree_iter_init(&iter, *nextid);
+	slot = idr_get_free(&idr->idr_rt, &iter, gfp, max);
 	if (IS_ERR(slot))
 		return PTR_ERR(slot);
 
 	radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr);
 	radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE);
 
-	if (index)
-		*index = iter.index;
+	*nextid = iter.index;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(idr_alloc_cmn);
+EXPORT_SYMBOL_GPL(idr_alloc_ul);
+
+/**
+ * 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().
+ */
+int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
+{
+	unsigned long id = start;
+	int ret;
+
+	if (WARN_ON_ONCE(start < 0))
+		return -EINVAL;
+
+	ret = idr_alloc_ul(idr, ptr, &id, end > 0 ? end - 1 : INT_MAX, gfp);
+
+	if (ret)
+		return ret;
+
+	return id;
+}
+EXPORT_SYMBOL_GPL(idr_alloc);
 
 /**
  * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
@@ -121,7 +170,7 @@ void *idr_get_next(struct idr *idr, int *nextid)
 }
 EXPORT_SYMBOL(idr_get_next);
 
-void *idr_get_next_ext(struct idr *idr, unsigned long *nextid)
+void *idr_get_next_ul(struct idr *idr, unsigned long *nextid)
 {
 	struct radix_tree_iter iter;
 	void __rcu **slot;
@@ -133,7 +182,7 @@ void *idr_get_next_ext(struct idr *idr, unsigned long *nextid)
 	*nextid = iter.index;
 	return rcu_dereference_raw(*slot);
 }
-EXPORT_SYMBOL(idr_get_next_ext);
+EXPORT_SYMBOL(idr_get_next_ul);
 
 /**
  * idr_replace - replace pointer for given id
@@ -149,16 +198,7 @@ EXPORT_SYMBOL(idr_get_next_ext);
  * Returns: 0 on success.  %-ENOENT indicates that @id was not found.
  * %-EINVAL indicates that @id or @ptr were not valid.
  */
-void *idr_replace(struct idr *idr, void *ptr, int id)
-{
-	if (WARN_ON_ONCE(id < 0))
-		return ERR_PTR(-EINVAL);
-
-	return idr_replace_ext(idr, ptr, id);
-}
-EXPORT_SYMBOL(idr_replace);
-
-void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long id)
+void *idr_replace(struct idr *idr, void *ptr, unsigned long id)
 {
 	struct radix_tree_node *node;
 	void __rcu **slot = NULL;
@@ -175,7 +215,7 @@ void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long id)
 
 	return entry;
 }
-EXPORT_SYMBOL(idr_replace_ext);
+EXPORT_SYMBOL(idr_replace);
 
 /**
  * DOC: IDA description
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 8b1feca1230a..9fcd4e5c5237 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -2139,7 +2139,7 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
 }
 EXPORT_SYMBOL(ida_pre_get);
 
-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)
 {
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index a306974e2fb4..131817ab3ad3 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -73,7 +73,7 @@ static void free_tcf(struct rcu_head *head)
 static void tcf_idr_remove(struct tcf_idrinfo *idrinfo, struct tc_action *p)
 {
 	spin_lock_bh(&idrinfo->lock);
-	idr_remove_ext(&idrinfo->action_idr, p->tcfa_index);
+	idr_remove(&idrinfo->action_idr, p->tcfa_index);
 	spin_unlock_bh(&idrinfo->lock);
 	gen_kill_estimator(&p->tcfa_rate_est);
 	/*
@@ -121,7 +121,7 @@ static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 
 	s_i = cb->args[0];
 
-	idr_for_each_entry_ext(idr, p, id) {
+	idr_for_each_entry_ul(idr, p, id) {
 		index++;
 		if (index < s_i)
 			continue;
@@ -178,7 +178,7 @@ static int tcf_del_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 	if (nla_put_string(skb, TCA_KIND, ops->kind))
 		goto nla_put_failure;
 
-	idr_for_each_entry_ext(idr, p, id) {
+	idr_for_each_entry_ul(idr, p, id) {
 		ret = __tcf_idr_release(p, false, true);
 		if (ret == ACT_P_DELETED) {
 			module_put(p->ops->owner);
@@ -216,10 +216,10 @@ EXPORT_SYMBOL(tcf_generic_walker);
 
 static struct tc_action *tcf_idr_lookup(u32 index, struct tcf_idrinfo *idrinfo)
 {
-	struct tc_action *p = NULL;
+	struct tc_action *p;
 
 	spin_lock_bh(&idrinfo->lock);
-	p = idr_find_ext(&idrinfo->action_idr, index);
+	p = idr_find(&idrinfo->action_idr, index);
 	spin_unlock_bh(&idrinfo->lock);
 
 	return p;
@@ -296,10 +296,10 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
 	spin_lock_init(&p->tcfa_lock);
 	/* user doesn't specify an index */
 	if (!index) {
+		idr_index = 1;
 		idr_preload(GFP_KERNEL);
 		spin_lock_bh(&idrinfo->lock);
-		err = idr_alloc_ext(idr, NULL, &idr_index, 1, 0,
-				    GFP_ATOMIC);
+		err = idr_alloc_ul(idr, NULL, &idr_index, UINT_MAX, GFP_ATOMIC);
 		spin_unlock_bh(&idrinfo->lock);
 		idr_preload_end();
 		if (err) {
@@ -309,10 +309,10 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
 		}
 		p->tcfa_index = idr_index;
 	} else {
+		idr_index = index;
 		idr_preload(GFP_KERNEL);
 		spin_lock_bh(&idrinfo->lock);
-		err = idr_alloc_ext(idr, NULL, NULL, index, index + 1,
-				    GFP_ATOMIC);
+		err = idr_alloc_ul(idr, NULL, &idr_index, index, GFP_ATOMIC);
 		spin_unlock_bh(&idrinfo->lock);
 		idr_preload_end();
 		if (err)
@@ -345,7 +345,7 @@ void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a)
 	struct tcf_idrinfo *idrinfo = tn->idrinfo;
 
 	spin_lock_bh(&idrinfo->lock);
-	idr_replace_ext(&idrinfo->action_idr, a, a->tcfa_index);
+	idr_replace(&idrinfo->action_idr, a, a->tcfa_index);
 	spin_unlock_bh(&idrinfo->lock);
 }
 EXPORT_SYMBOL(tcf_idr_insert);
@@ -358,7 +358,7 @@ void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
 	int ret;
 	unsigned long id = 1;
 
-	idr_for_each_entry_ext(idr, p, id) {
+	idr_for_each_entry_ul(idr, p, id) {
 		ret = __tcf_idr_release(p, false, true);
 		if (ret == ACT_P_DELETED)
 			module_put(ops->owner);
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 1a267e77c6de..ad30968f587d 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -298,7 +298,7 @@ static void __fl_delete(struct tcf_proto *tp, struct cls_fl_filter *f)
 {
 	struct cls_fl_head *head = rtnl_dereference(tp->root);
 
-	idr_remove_ext(&head->handle_idr, f->handle);
+	idr_remove(&head->handle_idr, f->handle);
 	list_del_rcu(&f->list);
 	if (!tc_skip_hw(f->flags))
 		fl_hw_destroy_filter(tp, f);
@@ -341,7 +341,7 @@ static void *fl_get(struct tcf_proto *tp, u32 handle)
 {
 	struct cls_fl_head *head = rtnl_dereference(tp->root);
 
-	return idr_find_ext(&head->handle_idr, handle);
+	return idr_find(&head->handle_idr, handle);
 }
 
 static const struct nla_policy fl_policy[TCA_FLOWER_MAX + 1] = {
@@ -901,8 +901,9 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 		goto errout;
 
 	if (!handle) {
-		err = idr_alloc_ext(&head->handle_idr, fnew, &idr_index,
-				    1, 0x80000000, GFP_KERNEL);
+		idr_index = 1;
+		err = idr_alloc_ul(&head->handle_idr, fnew, &idr_index,
+				    INT_MAX, GFP_KERNEL);
 		if (err)
 			goto errout;
 		fnew->handle = idr_index;
@@ -910,8 +911,9 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 
 	/* user specifies a handle and it doesn't exist */
 	if (handle && !fold) {
-		err = idr_alloc_ext(&head->handle_idr, fnew, &idr_index,
-				    handle, handle + 1, GFP_KERNEL);
+		idr_index = handle;
+		err = idr_alloc_ul(&head->handle_idr, fnew, &idr_index,
+				    handle, GFP_KERNEL);
 		if (err)
 			goto errout;
 		fnew->handle = idr_index;
@@ -970,7 +972,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 
 	if (fold) {
 		fnew->handle = handle;
-		idr_replace_ext(&head->handle_idr, fnew, fnew->handle);
+		idr_replace(&head->handle_idr, fnew, fnew->handle);
 		list_replace_rcu(&fold->list, &fnew->list);
 		tcf_unbind_filter(tp, &fold->res);
 		call_rcu(&fold->rcu, fl_destroy_filter);
-- 
2.14.1

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