[PATCH] asm-generic: Conditionally enable do_softirq_own_stack() via Kconfig.

From: Sebastian Andrzej Siewior
Date: Tue Aug 09 2022 - 11:57:44 EST


Remove the CONFIG_PREEMPT_RT symbol from the ifdef around
do_softirq_own_stack() and move it to Kconfig instead.

Enable softirq stacks based on SOFTIRQ_ON_OWN_STACK which depends on
HAVE_SOFTIRQ_ON_OWN_STACK and its default value is set to !PREEMPT_RT.
This ensures that softirq stacks are not used on PREEMPT_RT and avoids
a 'select' statement on an option which has a 'depends' statement.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
arch/Kconfig | 4 ++++
arch/arm/kernel/irq.c | 2 +-
arch/parisc/kernel/irq.c | 2 +-
arch/powerpc/kernel/irq.c | 4 ++--
arch/s390/include/asm/softirq_stack.h | 2 +-
arch/sh/kernel/irq.c | 2 +-
arch/sparc/kernel/irq_64.c | 2 +-
arch/x86/include/asm/irq_stack.h | 2 +-
arch/x86/kernel/irq_32.c | 2 +-
include/asm-generic/softirq_stack.h | 2 +-
10 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index f330410da63a6..966aa6f82a5b9 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -924,6 +924,10 @@ config HAVE_SOFTIRQ_ON_OWN_STACK
Architecture provides a function to run __do_softirq() on a
separate stack.

+config SOFTIRQ_ON_OWN_STACK
+ def_bool !PREEMPT_RT
+ depends on HAVE_SOFTIRQ_ON_OWN_STACK
+
config ALTERNATE_USER_ADDRESS_SPACE
bool
help
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 034cb48c9eeb8..fe28fc1f759d9 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -70,7 +70,7 @@ static void __init init_irq_stacks(void)
}
}

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
static void ____do_softirq(void *arg)
{
__do_softirq();
diff --git a/arch/parisc/kernel/irq.c b/arch/parisc/kernel/irq.c
index fbb882cb8dbb5..b05055f3ba4b8 100644
--- a/arch/parisc/kernel/irq.c
+++ b/arch/parisc/kernel/irq.c
@@ -480,7 +480,7 @@ static void execute_on_irq_stack(void *func, unsigned long param1)
*irq_stack_in_use = 1;
}

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
void do_softirq_own_stack(void)
{
execute_on_irq_stack(__do_softirq, 0);
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 0f17268c1f0bb..9ede61a5a469e 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -199,7 +199,7 @@ static inline void check_stack_overflow(unsigned long sp)
}
}

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
static __always_inline void call_do_softirq(const void *sp)
{
/* Temporarily switch r1 to sp, call __do_softirq() then restore r1. */
@@ -335,7 +335,7 @@ void *mcheckirq_ctx[NR_CPUS] __read_mostly;
void *softirq_ctx[NR_CPUS] __read_mostly;
void *hardirq_ctx[NR_CPUS] __read_mostly;

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
void do_softirq_own_stack(void)
{
call_do_softirq(softirq_ctx[smp_processor_id()]);
diff --git a/arch/s390/include/asm/softirq_stack.h b/arch/s390/include/asm/softirq_stack.h
index af68d6c1d5840..1ac5115d3115e 100644
--- a/arch/s390/include/asm/softirq_stack.h
+++ b/arch/s390/include/asm/softirq_stack.h
@@ -5,7 +5,7 @@
#include <asm/lowcore.h>
#include <asm/stacktrace.h>

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
static inline void do_softirq_own_stack(void)
{
call_on_stack(0, S390_lowcore.async_stack, void, __do_softirq);
diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index 9092767380780..4e6835de54cf8 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -149,7 +149,7 @@ void irq_ctx_exit(int cpu)
hardirq_ctx[cpu] = NULL;
}

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
void do_softirq_own_stack(void)
{
struct thread_info *curctx;
diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
index 41fa1be980a33..72da2e10e2559 100644
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -855,7 +855,7 @@ void __irq_entry handler_irq(int pil, struct pt_regs *regs)
set_irq_regs(old_regs);
}

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
void do_softirq_own_stack(void)
{
void *orig_sp, *sp = softirq_stack[smp_processor_id()];
diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h
index 63f818aedf770..147cb8fdda92e 100644
--- a/arch/x86/include/asm/irq_stack.h
+++ b/arch/x86/include/asm/irq_stack.h
@@ -203,7 +203,7 @@
IRQ_CONSTRAINTS, regs, vector); \
}

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
/*
* Macro to invoke __do_softirq on the irq stack. This is only called from
* task context when bottom halves are about to be reenabled and soft
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index e5dd6da78713b..01833ebf5e8e3 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -132,7 +132,7 @@ int irq_init_percpu_irqstack(unsigned int cpu)
return 0;
}

-#ifndef CONFIG_PREEMPT_RT
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
void do_softirq_own_stack(void)
{
struct irq_stack *irqstk;
diff --git a/include/asm-generic/softirq_stack.h b/include/asm-generic/softirq_stack.h
index d3e2d81656e04..2a67aed9ac528 100644
--- a/include/asm-generic/softirq_stack.h
+++ b/include/asm-generic/softirq_stack.h
@@ -2,7 +2,7 @@
#ifndef __ASM_GENERIC_SOFTIRQ_STACK_H
#define __ASM_GENERIC_SOFTIRQ_STACK_H

-#if defined(CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK) && !defined(CONFIG_PREEMPT_RT)
+#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
void do_softirq_own_stack(void);
#else
static inline void do_softirq_own_stack(void)
--
2.36.1