maple_tree: assert static storage for DEFINE_MTREE()

DEFINE_MTREE() uses MTREE_INIT(), which initializes the tree's embedded
lock with a static spinlock initializer.  If the tree is an automatic
local object, lockdep rejects its address as a non-static class key and
disables locking validation on the first lock acquisition.

Apply ASSERT_STATIC_STORAGE() to DEFINE_MTREE() to catch automatic local
definitions at compile time.  For example:

  void example(void)
  {
          DEFINE_MTREE(mt);
          mtree_destroy(&mt);
  }

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_MTREE'
    DEFINE_MTREE(mt);

File-scope definitions and static local trees remain valid.  Automatic
local trees must instead use mt_init() or mt_init_flags().  Direct uses of
MTREE_INIT() and MTREE_INIT_EXT() are unchanged.

Replace the local DEFINE_MTREE() in the interval-tree span test with a
plain declaration; the test already initializes the tree with
mt_init_flags() before use.  Convert the three local Maple Trees in the
userspace radix-tree tests to mt_init().

Validated file-scope and static local definitions with a kernel object
build, and confirmed that an automatic local definition fails to compile. 
The Maple Tree test and region allocation benchmark objects also build
with lockdep enabled.

Link: https://lore.kernel.org/20260911221444.1523311-4-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>

0 files changed, 0 insertions, 0 deletions