[PATCH RT v2 1/2] riscv: add PREEMPT_AUTO support

[Jisheng Zhang <jszhang@kernel.org>]

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 <jszhang@kernel.org>
---
 arch/riscv/Kconfig                   | 1 +
 arch/riscv/include/asm/thread_info.h | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d607ab0f7c6d..5f43b82691fc 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -135,6 +135,7 @@ 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
diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h
index 1833beb00489..c5aebcdafd7b 100644
--- a/arch/riscv/include/asm/thread_info.h
+++ b/arch/riscv/include/asm/thread_info.h
@@ -85,6 +85,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
  * - 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 */
@@ -99,6 +100,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
+#define _TIF_ARCH_RESCHED_LAZY	(1 << TIF_ARCH_RESCHED_LAZY)
 
 #define _TIF_WORK_MASK \
 	(_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED | \
-- 
2.40.1


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