UPSTREAM: thread_info: include <current.h> for THREAD_INFO_IN_TASK

When CONFIG_THREAD_INFO_IN_TASK is selected, the current_thread_info()
macro relies on current having been defined prior to its use. However,
not all users of current_thread_info() include <asm/current.h>, and thus
current is not guaranteed to be defined.

When CONFIG_THREAD_INFO_IN_TASK is not selected, it's possible that
get_current() / current are based upon current_thread_info(), and
<asm/current.h> includes <asm/thread_info.h>. Thus always including
<asm/current.h> would result in circular dependences on some platforms.

To ensure both cases work, this patch includes <asm/current.h>, but only
when CONFIG_THREAD_INFO_IN_TASK is selected.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Bug: 38331309
Change-Id: Ia981a829798d60a54d4e3eb679d8e24b01228357
(cherry picked from commit dc3d2a679cd8631b8a570fc8ca5f4712d7d25698)
Signed-off-by: Zubin Mithra <zsm@google.com>

diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index e8369b0..8933ecc 100644 (file)
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -12,17 +12,12 @@
 #include <linux/restart_block.h>
 
 #ifdef CONFIG_THREAD_INFO_IN_TASK
-struct thread_info {
-       u32                     flags;          /* low level flags */
-};
-
-#define INIT_THREAD_INFO(tsk)                  \
-{                                              \
-       .flags          = 0,                    \
-}
-#endif
-
-#ifdef CONFIG_THREAD_INFO_IN_TASK
+/*
+ * For CONFIG_THREAD_INFO_IN_TASK kernels we need <asm/current.h> for the
+ * definition of current, but for !CONFIG_THREAD_INFO_IN_TASK kernels,
+ * including <asm/current.h> can cause a circular dependency on some platforms.
+ */
+#include <asm/current.h>
 #define current_thread_info() ((struct thread_info *)current)
 #endif