[PATCH 2/3] idr: assert static storage for DEFINE_IDA()

[Yury Norov]

DEFINE_IDA() uses IDA_INIT(), which initializes the embedded XArray lock
with a static spinlock initializer. For an automatic local IDA, lockdep
cannot use the lock address as a persistent class key and reports
"INFO: trying to register non-static key" before disabling itself.

Apply ASSERT_STATIC_STORAGE() to DEFINE_IDA() so that this misuse is
rejected at compile time. For example:

  void example(void)
  {
          DEFINE_IDA(ida);
          ida_destroy(&ida);
  }

GCC reports:

  error: initializer element is not constant
    name##_storage_check = &(name)
                           ^
  note: in expansion of macro 'ASSERT_STATIC_STORAGE'
    ASSERT_STATIC_STORAGE(name)
  note: in expansion of macro 'DEFINE_IDA'
    DEFINE_IDA(ida);

File-scope definitions and static DEFINE_IDA() within a function remain
valid. Automatic local IDAs must instead be initialized with ida_init().
Direct uses of IDA_INIT() are not covered by this declaration check.

Convert the five automatic local IDAs in the userspace radix-tree tests
to ida_init() so they satisfy the new requirement.

Validated file-scope and static local definitions with a kernel object
build, and confirmed that an automatic local definition fails to compile.

Signed-off-by: Yury Norov <ynorov at nvidia.com>
---
 include/linux/idr.h                 |  5 ++++-
 tools/testing/radix-tree/idr-test.c | 20 +++++++++++++++-----
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index 789e23e67444..e2a4b6298511 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -16,6 +16,7 @@
 #include <linux/gfp.h>
 #include <linux/percpu.h>
 #include <linux/cleanup.h>
+#include <linux/compiler.h>
 
 struct idr {
 	struct radix_tree_root	idr_rt;
@@ -269,7 +270,9 @@ struct ida {
 #define IDA_INIT(name)	{						\
 	.xa = XARRAY_INIT(name, IDA_INIT_FLAGS)				\
 }
-#define DEFINE_IDA(name)	struct ida name = IDA_INIT(name)
+#define DEFINE_IDA(name)							\
+	struct ida name = IDA_INIT(name);					\
+	ASSERT_STATIC_STORAGE(name)
 
 int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t);
 void ida_free(struct ida *, unsigned int id);
diff --git a/tools/testing/radix-tree/idr-test.c b/tools/testing/radix-tree/idr-test.c
index 945144e98507..6fcba5b5870b 100644
--- a/tools/testing/radix-tree/idr-test.c
+++ b/tools/testing/radix-tree/idr-test.c
@@ -460,9 +460,11 @@ void ida_dump(struct ida *);
  */
 void ida_check_nomem(void)
 {
-	DEFINE_IDA(ida);
+	struct ida ida;
 	int id;
 
+	ida_init(&ida);
+
 	id = ida_alloc_min(&ida, 256, GFP_NOWAIT);
 	IDA_BUG_ON(&ida, id != -ENOMEM);
 	id = ida_alloc_min(&ida, 1UL << 30, GFP_NOWAIT);
@@ -475,9 +477,11 @@ void ida_check_nomem(void)
  */
 void ida_check_conv_user(void)
 {
-	DEFINE_IDA(ida);
+	struct ida ida;
 	unsigned long i;
 
+	ida_init(&ida);
+
 	for (i = 0; i < 1000000; i++) {
 		int id = ida_alloc(&ida, GFP_NOWAIT);
 		if (id == -ENOMEM) {
@@ -496,11 +500,13 @@ void ida_check_conv_user(void)
 
 void ida_check_random(void)
 {
-	DEFINE_IDA(ida);
+	struct ida ida;
 	DECLARE_BITMAP(bitmap, 2048);
 	unsigned int i;
 	time_t s = time(NULL);
 
+	ida_init(&ida);
+
  repeat:
 	memset(bitmap, 0, sizeof(bitmap));
 	for (i = 0; i < 100000; i++) {
@@ -522,9 +528,11 @@ void ida_check_random(void)
 
 void ida_alloc_free_test(void)
 {
-	DEFINE_IDA(ida);
+	struct ida ida;
 	unsigned long i;
 
+	ida_init(&ida);
+
 	for (i = 0; i < 10000; i++)
 		assert(ida_alloc_max(&ida, 20000, GFP_KERNEL) == i);
 	assert(ida_alloc_range(&ida, 5, 30, GFP_KERNEL) < 0);
@@ -576,10 +584,12 @@ static void *ida_leak_fn(void *arg)
 
 void ida_thread_tests(void)
 {
-	DEFINE_IDA(ida);
+	struct ida ida;
 	pthread_t threads[20];
 	int i;
 
+	ida_init(&ida);
+
 	for (i = 0; i < ARRAY_SIZE(threads); i++)
 		if (pthread_create(&threads[i], NULL, ida_random_fn, NULL)) {
 			perror("creating ida thread");
-- 
2.53.0