sched/core, x86: Make struct thread_info arch specific again
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.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 2aaca53..ad6f5eb0 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -52,6 +52,15 @@
#include <asm/cpufeature.h>
#include <linux/atomic.h>
+struct thread_info {
+ unsigned long flags; /* low level flags */
+};
+
+#define INIT_THREAD_INFO(tsk) \
+{ \
+ .flags = 0, \
+}
+
#define init_stack (init_thread_union.stack)
#else /* !__ASSEMBLY__ */