Messages in this thread Patch in this message | | | From | Christophe Leroy <> | Subject | [RFC PATCH v2 13/13] powerpc/kernel: Do not use READ_ONCE() to access current thread_info flags | Date | Sun, 5 Apr 2020 17:44:48 +0000 (UTC) |
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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@c-s.fr> --- 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
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