idr: assert static storage for DEFINE_IDA()

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.

Link: https://lore.kernel.org/20260911221444.1523311-3-ynorov@nvidia.com
Signed-off-by: Yury Norov <ynorov@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: Christopher Li <sparse@chrisli.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>

1 files changed, 4 insertions, 1 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);