Subject: [PATCH] riscv: add PREEMPT_AUTO support
From: Jisheng Zhang <[email-masked]>
Date: Tue, 31 Oct 2023 22:35:20 +0800

riscv has switched to GENERIC_ENTRY, so adding PREEMPT_AUTO is as simple
as adding TIF_ARCH_RESCHED_LAZY related definitions and enabling
HAVE_PREEMPT_AUTO.

Signed-off-by: Jisheng Zhang <[email-masked]>
Signed-off-by: Sebastian Andrzej Siewior <[email-masked]>
---
 arch/riscv/Kconfig                   |    1 +
 arch/riscv/include/asm/thread_info.h |    2 ++
 2 files changed, 3 insertions(+)

Index: linux-6.8.2-rt10/arch/riscv/Kconfig
===================================================================
--- linux-6.8.2-rt10.orig/arch/riscv/Kconfig
+++ linux-6.8.2-rt10/arch/riscv/Kconfig
@@ -142,6 +142,7 @@ config RISCV
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
 	select HAVE_PREEMPT_DYNAMIC_KEY if !XIP_KERNEL
+	select HAVE_PREEMPT_AUTO
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RETHOOK if !XIP_KERNEL
 	select HAVE_RSEQ
Index: linux-6.8.2-rt10/arch/riscv/include/asm/thread_info.h
===================================================================
--- linux-6.8.2-rt10.orig/arch/riscv/include/asm/thread_info.h
+++ linux-6.8.2-rt10/arch/riscv/include/asm/thread_info.h
@@ -94,6 +94,7 @@ int arch_dup_task_struct(struct task_str
  * - pending work-to-be-done flags are in lowest half-word
  * - other flags in upper half-word(s)
  */
+#define TIF_ARCH_RESCHED_LAZY	0	/* Lazy rescheduling */
 #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
@@ -104,6 +105,7 @@ int arch_dup_task_struct(struct task_str
 #define TIF_32BIT		11	/* compat-mode 32bit process */
 #define TIF_RISCV_V_DEFER_RESTORE	12 /* restore Vector before returing to user */
 
+#define _TIF_ARCH_RESCHED_LAZY	(1 << TIF_ARCH_RESCHED_LAZY)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)