PREEMPT_RT preempts softirqs and the current implementation avoids
do_softirq_own_stack() and only uses __do_softirq().
Disable the unused softirqs stacks on PREEMPT_RT to safe some memory and
ensure that do_softirq_own_stack() is not used bwcause it is not
expected.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
Initially I aimed only for the asm-generic bits and arm since I have
most bits of the port ready. Arnd then suggested to do all arches at
once and here it is.
I tried to keep it minimal in sense that I didn't remove the dedicated
softirq-stacks on parisc or powerpc for instance. That would add another
few ifdefs and I don't know if we manage to get it up and running on
parisc. I do have the missing bits for powerpc however ;)
arch/arm/kernel/irq.c | 3 ++-
arch/parisc/kernel/irq.c | 2 ++
arch/powerpc/kernel/irq.c | 4 ++++
arch/s390/include/asm/softirq_stack.h | 3 ++-
arch/sh/kernel/irq.c | 2 ++
arch/sparc/kernel/irq_64.c | 2 ++
include/asm-generic/softirq_stack.h | 2 +-
7 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 5c6f8d11a3ce5..034cb48c9eeb8 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -70,6 +70,7 @@ static void __init init_irq_stacks(void)
}
}
+#ifndef CONFIG_PREEMPT_RT
static void ____do_softirq(void *arg)
{
__do_softirq();
@@ -80,7 +81,7 @@ void do_softirq_own_stack(void)
call_with_stack(____do_softirq, NULL,
__this_cpu_read(irq_stack_ptr));
}
-
+#endif
#endif
int arch_show_interrupts(struct seq_file *p, int prec)
diff --git a/arch/parisc/kernel/irq.c b/arch/parisc/kernel/irq.c
index 0fe2d79fb123f..eba193bcdab1b 100644
--- a/arch/parisc/kernel/irq.c
+++ b/arch/parisc/kernel/irq.c
@@ -480,10 +480,12 @@ static void execute_on_irq_stack(void *func, unsigned long param1)
*irq_stack_in_use = 1;
}
+#ifndef CONFIG_PREEMPT_RT
void do_softirq_own_stack(void)
{
execute_on_irq_stack(__do_softirq, 0);
}
+#endif
#endif /* CONFIG_IRQSTACKS */
/* ONLY called from entry.S:intr_extint() */
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index dd09919c3c668..0822a274a549c 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -611,6 +611,7 @@ static inline void check_stack_overflow(void)
}
}
+#ifndef CONFIG_PREEMPT_RT
static __always_inline void call_do_softirq(const void *sp)
{
/* Temporarily switch r1 to sp, call __do_softirq() then restore r1. */
@@ -629,6 +630,7 @@ static __always_inline void call_do_softirq(const void *sp)
"r11", "r12"
);
}
+#endif
static __always_inline void call_do_irq(struct pt_regs *regs, void *sp)
{
@@ -747,10 +749,12 @@ 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
void do_softirq_own_stack(void)
{
call_do_softirq(softirq_ctx[smp_processor_id()]);
}
+#endif
irq_hw_number_t virq_to_hw(unsigned int virq)
{
diff --git a/arch/s390/include/asm/softirq_stack.h b/arch/s390/include/asm/softirq_stack.h
index fd17f25704bd5..af68d6c1d5840 100644
--- a/arch/s390/include/asm/softirq_stack.h
+++ b/arch/s390/include/asm/softirq_stack.h
@@ -5,9 +5,10 @@
#include <asm/lowcore.h>
#include <asm/stacktrace.h>
+#ifndef CONFIG_PREEMPT_RT
static inline void do_softirq_own_stack(void)
{
call_on_stack(0, S390_lowcore.async_stack, void, __do_softirq);
}
-
+#endif
#endif /* __ASM_S390_SOFTIRQ_STACK_H */
diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index ef0f0827cf575..2d3eca8fee011 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -149,6 +149,7 @@ void irq_ctx_exit(int cpu)
hardirq_ctx[cpu] = NULL;
}
+#ifndef CONFIG_PREEMPT_RT
void do_softirq_own_stack(void)
{
struct thread_info *curctx;
@@ -176,6 +177,7 @@ void do_softirq_own_stack(void)
"r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
);
}
+#endif
#else
static inline void handle_one_irq(unsigned int irq)
{
diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
index c8848bb681a11..41fa1be980a33 100644
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -855,6 +855,7 @@ void __irq_entry handler_irq(int pil, struct pt_regs *regs)
set_irq_regs(old_regs);
}
+#ifndef CONFIG_PREEMPT_RT
void do_softirq_own_stack(void)
{
void *orig_sp, *sp = softirq_stack[smp_processor_id()];
@@ -869,6 +870,7 @@ void do_softirq_own_stack(void)
__asm__ __volatile__("mov %0, %%sp"
: : "r" (orig_sp));
}
+#endif
#ifdef CONFIG_HOTPLUG_CPU
void fixup_irqs(void)
diff --git a/include/asm-generic/softirq_stack.h b/include/asm-generic/softirq_stack.h
index eceeecf6a5bd8..d3e2d81656e04 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
-#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
+#if defined(CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK) && !defined(CONFIG_PREEMPT_RT)
void do_softirq_own_stack(void);
#else
static inline void do_softirq_own_stack(void)
--
2.36.1
