From: Heiko Carstens heiko.carstens@de.ibm.com
commit c8061485a0d7569a865a3cc3c63347b0f42b3765 upstream.
The following commit:
c65eacbe290b ("sched/core: Allow putting thread_info into task_struct")
... made 'struct thread_info' a generic struct with only a single ::flags member, if CONFIG_THREAD_INFO_IN_TASK_STRUCT=y is selected.
This change however seems to be quite x86 centric, since at least the generic preemption code (asm-generic/preempt.h) assumes that struct thread_info also has a preempt_count member, which apparently was not true for x86.
We could add a bit more #ifdefs to solve this problem too, but it seems to be much simpler to make struct thread_info arch specific again. This also makes the conversion to THREAD_INFO_IN_TASK_STRUCT a bit easier for architectures that have a couple of arch specific stuff in their thread_info definition.
The arch specific stuff _could_ be moved to thread_struct. However keeping them in thread_info makes it easier: accessing thread_info members is simple, since it is at the beginning of the task_struct, while the thread_struct is at the end. At least on s390 the offsets needed to access members of the thread_struct (with task_struct as base) are too large for various asm instructions. This is not a problem when keeping these members within thread_info.
Signed-off-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Mark Rutland mark.rutland@arm.com Acked-by: Thomas Gleixner tglx@linutronix.de Cc: Andrew Morton akpm@linux-foundation.org Cc: Andy Lutomirski luto@kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: keescook@chromium.org Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/1476901693-8492-2-git-send-email-mark.rutland@arm.c... Signed-off-by: Ingo Molnar mingo@kernel.org [ zhangyi: skip defination of INIT_THREAD_INFO and struct thread_info ] Signed-off-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/thread_info.h | 11 ----------- 1 file changed, 11 deletions(-)
--- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -14,17 +14,6 @@ struct timespec; struct compat_timespec;
#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 #define current_thread_info() ((struct thread_info *)current) #endif