[RFC PATCH 02/13] arm64: preempt: Treat should_resched() as unlikely

[Mark Rutland]

The arm64 implementation of should_resched() doesn't treat the need to
resched as unlikely, while all other implementations do, e.g.

* asm-generic since:
  bdb43806589096ac ("sched: Extract the basic add/sub preempt_count modifiers")

* x86 since:
  c2daa3bed53a8117 ("sched, x86: Provide a per-cpu preempt_count implementation")

* s390 since:
  c360192bf4a8dc72 ("s390/preempt: move preempt_count to the lowcore")

Do the same for arm64.

Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Ada Couprie Diaz <ada.coupriediaz@xxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Vladimir Murzin <vladimir.murzin@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
---
 arch/arm64/include/asm/preempt.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h
index ca2ad1a8db095..3ef24ab8f3399 100644
--- a/arch/arm64/include/asm/preempt.h
+++ b/arch/arm64/include/asm/preempt.h
@@ -58,7 +58,7 @@ static inline void __preempt_count_sub(int val)
 static inline bool should_resched(int preempt_offset)
 {
 	u64 pc = READ_ONCE(current_thread_info()->preempt_count);
-	return pc == preempt_offset;
+	return unlikely(pc == preempt_offset);
 }
 
 static inline bool __preempt_count_dec_and_test(void)
-- 
2.30.2