From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Sat, 9 Mar 2019 19:24:26 +0000 (-0800)
Subject: kernel - Fix IDR bugs
X-Git-Tag: v5.7.0~484
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/d0975e245898ed621e15cfb81acdd4a402082d44

kernel - Fix IDR bugs

* Allow ptr to be NULL in idr_remove() and idr_replace().

* Note that linux ERR returns from idr_replace() still not implemented
  (requires the related ERR macros to be moved out of drm).  idr_replace()
  still returns NULL when the id cannot be found.

Requested-by: aly
---

diff --git a/share/man/man9/idr.9 b/share/man/man9/idr.9
index 777787e411..07509b790f 100644
--- a/share/man/man9/idr.9
+++ b/share/man/man9/idr.9
@@ -129,7 +129,8 @@ The
 .Fn idr_remove
 function removes the specified
 .Fa id
-from the tree.
+from the tree, returning its pointer.
+NULL is returned if the id could not be found.
 .Pp
 The
 .Fn idr_remove_all
@@ -146,5 +147,6 @@ with the new pointer
 .Fa ptr .
 It returns
 .Dv NULL
-if the pointer is not found.
-This behavior is different from the Linux API.
+if the id is not found.
+This behavior is different from the Linux API, which returns ERR_PTR(-ENOENT)
+if the id could not be found.
diff --git a/sys/libkern/linux_idr.c b/sys/libkern/linux_idr.c
index 2688160531..86b7a6b3dd 100644
--- a/sys/libkern/linux_idr.c
+++ b/sys/libkern/linux_idr.c
@@ -58,6 +58,7 @@
 #define MALLOC_DEFINE(a, b, c)
 #define lwkt_gettoken(x)
 #define lwkt_reltoken(x)
+#undef kmalloc
 #define kmalloc(bytes, zone, flags)	calloc(bytes, 1)
 #define lwkt_token_init(a, b)
 #define lwkt_token_uninit(a)
@@ -72,7 +73,7 @@ main(int ac, char **av)
 {
 	char buf[256];
 	struct idr idr;
-	intptr_t generation = 0x10000000;
+	intptr_t generation = 0x0;
 	int error;
 	int id;
 
@@ -459,7 +460,7 @@ idr_grow(struct idr *idp, int want)
 	idp->idr_nexpands++;
 }
 
-void
+void *
 idr_remove(struct idr *idp, int id)
 {
 	void *ptr;
@@ -467,16 +468,19 @@ idr_remove(struct idr *idp, int id)
 	lwkt_gettoken(&idp->idr_token);
 	if (id < 0 || id >= idp->idr_count) {
 		lwkt_reltoken(&idp->idr_token);
-		return;
-	}
-	if ((ptr = idp->idr_nodes[id].data) == NULL) {
-		lwkt_reltoken(&idp->idr_token);
-		return;
+		return NULL;
 	}
+        if (idp->idr_nodes[id].allocated == 0) {
+                lwkt_reltoken(&idp->idr_token);
+                return NULL;
+        }
+	ptr = idp->idr_nodes[id].data;
 	idp->idr_nodes[id].data = NULL;
 	idr_reserve(idp, id, -1);
 	idrfixup(idp, id);
 	lwkt_reltoken(&idp->idr_token);
+
+	return ptr;
 }
 
 /*
@@ -549,7 +553,7 @@ idr_replace(struct idr *idp, void *ptr, int id)
 
 	lwkt_gettoken(&idp->idr_token);
 	idrnp = idr_get_node(idp, id);
-	if (idrnp == NULL || ptr == NULL) {
+	if (idrnp == NULL) {
 		ret = NULL;
 	} else {
 		ret = idrnp->data;
diff --git a/sys/sys/idr.h b/sys/sys/idr.h
index 79951fa2fa..f148eec809 100644
--- a/sys/sys/idr.h
+++ b/sys/sys/idr.h
@@ -39,8 +39,7 @@
  * IDR is a small Integer ID management library that provides an interface to
  * map integers with some pointer that can later be retrieved.
  *
- * NOTE: Pointer mapped by integer can't be NULL.
- *
+ * NOTE: Maintains compatibility with linux, allowing NULL pointers.
  */
 
 
@@ -73,7 +72,7 @@ struct idr {
 
 void	*idr_find(struct idr *idp, int id);
 void	*idr_replace(struct idr *idp, void *ptr, int id);
-void	 idr_remove(struct idr *idp, int id);
+void	*idr_remove(struct idr *idp, int id);
 void	 idr_remove_all(struct idr *idp);
 void	 idr_destroy(struct idr *idp);
 int	 idr_for_each(struct idr *idp, int (*fn)(int id, void *p, void *data), void *data);