[PATCH] kasan: Add a prototype of task_struct to avoid warning

[Arnd Bergmann <arnd@arndb.de>]

From: Masami Hiramatsu <mhiramat@kernel.org>

Add a prototype of task_struct to fix below warning on arm64.

In file included from arch/arm64/kernel/probes/kprobes.c:19:0:
include/linux/kasan.h:81:132: error: 'struct task_struct' declared inside parameter list will not be visible outside of this definition or declaration [-Werror]
 static inline void kasan_unpoison_task_stack(struct task_struct *task) {}

As same as other types (kmem_cache, page, and vm_struct) this adds a
prototype of task_struct data structure on top of kasan.h.

[arnd] A related warning was fixed before, but now appears in a different
line in the same file in v4.11-rc2. The patch from Masami Hiramatsu
still seems appropriate, so let's take his version.

Link: https://patchwork.kernel.org/patch/9569839/
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/kasan.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 1c823bef4c15..5734480c9590 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -6,6 +6,7 @@
 struct kmem_cache;
 struct page;
 struct vm_struct;
+struct task_struct;
 
 #ifdef CONFIG_KASAN
 
-- 
2.9.0