arch: remove ARCH_THREAD_STACK_ALLOCATOR

Patch series "Remove unused code after IA-64 removal".

While looking into something different I noticed that there are a couple
of Kconfig options which were only selected by IA-64 and which are now
unused.

So remove them and simplify the code a bit.


This patch (of 3):

IA-64 was the only architecture which selected ARCH_THREAD_STACK_ALLOCATOR.
IA-64 was removed with commit cf8e8658 ("arch: Remove Itanium (IA-64)
architecture"). Therefore remove support for ARCH_THREAD_STACK_ALLOCATOR as
well.

Link: https://lkml.kernel.org/r/20231116133638.1636277-1-hca@linux.ibm.com
Link: https://lkml.kernel.org/r/20231116133638.1636277-2-hca@linux.ibm.comSigned-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/Kconfig

@@ -320,10 +320,6 @@ config HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	  should be implemented. Without this, the entire thread_struct
 	  field in task_struct will be left whitelisted.
 
-# Select if arch has its private alloc_thread_stack() function
-config ARCH_THREAD_STACK_ALLOCATOR
-	bool
-
 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
 	bool

kernel/fork.c

@@ -179,8 +179,6 @@ static inline void free_task_struct(struct task_struct *tsk)
 }
 #endif
 
-#ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
-
 /*
  * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
  * kmemcache based allocator.
@@ -412,24 +410,6 @@ void thread_stack_cache_init(void)
 }
 
 # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
-#else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
-
-static int alloc_thread_stack_node(struct task_struct *tsk, int node)
-{
-	unsigned long *stack;
-
-	stack = arch_alloc_thread_stack_node(tsk, node);
-	tsk->stack = stack;
-	return stack ? 0 : -ENOMEM;
-}
-
-static void free_thread_stack(struct task_struct *tsk)
-{
-	arch_free_thread_stack(tsk);
-	tsk->stack = NULL;
-}
-
-#endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
 
 /* SLAB cache for signal_struct structures (tsk->signal) */
 static struct kmem_cache *signal_cachep;