UPSTREAM: Fix build break in fork.c when THREAD_SIZE < PAGE_SIZE

Commit b235beea9e99 ("Clarify naming of thread info/stack allocators")
breaks the build on some powerpc configs, where THREAD_SIZE < PAGE_SIZE:

  kernel/fork.c:235:2: error: implicit declaration of function 'free_thread_stack'
  kernel/fork.c:355:8: error: assignment from incompatible pointer type
    stack = alloc_thread_stack_node(tsk, node);
    ^

Fix it by renaming free_stack() to free_thread_stack(), and updating the
return type of alloc_thread_stack_node().

Fixes: b235beea9e99 ("Clarify naming of thread info/stack allocators")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Bug: 38331309
Change-Id: I5b7f920b459fb84adf5fc75f83bb488b855c4deb
(cherry picked from commit 9521d39976db20f8ef9b56af66661482a17d5364)
Signed-off-by: Zubin Mithra <zsm@google.com>
1 file changed