From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH] x86/softirq: Disable softirq stacks on PREEMPT_RT
Date: Fri, 24 Sep 2021 18:12:45 +0200 [thread overview]
Message-ID: <20210924161245.2357247-1-bigeasy@linutronix.de> (raw)
From: Thomas Gleixner <tglx@linutronix.de>
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 which is not expected.
[bigeasy: commit description.]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/include/asm/irq_stack.h | 3 +++
arch/x86/kernel/irq_32.c | 2 ++
2 files changed, 5 insertions(+)
--- a/arch/x86/include/asm/irq_stack.h
+++ b/arch/x86/include/asm/irq_stack.h
@@ -185,6 +185,7 @@
IRQ_CONSTRAINTS, regs, vector); \
}
+#ifndef CONFIG_PREEMPT_RT
#define ASM_CALL_SOFTIRQ \
"call %P[__func] \n"
@@ -201,6 +202,8 @@
__this_cpu_write(hardirq_stack_inuse, false); \
}
+#endif
+
#else /* CONFIG_X86_64 */
/* System vector handlers always run on the stack they interrupted. */
#define run_sysvec_on_irqstack_cond(func, regs) \
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -132,6 +132,7 @@ int irq_init_percpu_irqstack(unsigned in
return 0;
}
+#ifndef CONFIG_PREEMPT_RT
void do_softirq_own_stack(void)
{
struct irq_stack *irqstk;
@@ -148,6 +149,7 @@ void do_softirq_own_stack(void)
call_on_stack(__do_softirq, isp);
}
+#endif
void __handle_irq(struct irq_desc *desc, struct pt_regs *regs)
{
next reply other threads:[~2021-09-24 16:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-24 16:12 Sebastian Andrzej Siewior [this message]
2021-10-29 10:07 ` [tip: irq/core] x86/softirq: Disable softirq stacks on PREEMPT_RT tip-bot2 for Thomas Gleixner
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