[RFC PATCH v2 13/13] powerpc/kernel: Do not use READ_ONCE() to access current thread_info flags

[Christophe Leroy]

current is a volatile pointer hold by r2 register.

READ_ONCE() is not required.

Before: 327 cycles on null_syscall
Before: 325 cycles on null_syscall

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
 arch/powerpc/kernel/syscall.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c
index 34fd66fd11a2..3d2f285b8a01 100644
--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c
@@ -164,7 +164,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
 again:
 #endif
 	local_irq_disable();
-	ti_flags = READ_ONCE(*ti_flagsp);
+	ti_flags = current_thread_info()->flags;
 	while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
 		local_irq_enable();
 		if (ti_flags & _TIF_NEED_RESCHED) {
@@ -180,7 +180,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
 			do_notify_resume(regs, ti_flags);
 		}
 		local_irq_disable();
-		ti_flags = READ_ONCE(*ti_flagsp);
+		ti_flags = current_thread_info()->flags;
 	}
 
 	if (IS_ENABLED(CONFIG_PPC_BOOK3S) && IS_ENABLED(CONFIG_PPC_FPU)) {
-- 
2.25.0