linux-kernel - [RFC PATCH 2/3] init: Require archs call start

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Date:   Tue,  9 May 2023 21:07:38 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Nicholas Piggin <npiggin@...il.com>, linux-arch@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [RFC PATCH 2/3] init: Require archs call start_kernel with arch irqs disabled

Let's require start_kernel() is called with arch_irqs_disabled. For now,
just correct that condition and print a warning if CONFIG_DEBUG_IRQFLAGS
is set.

This prevents core code from disabling irqs when they are already
disabled, in aid of eventually adding a debug check to catch that
condition.

Signed-off-by: Nicholas Piggin <npiggin@...il.com>
---
 init/main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index af50044deed5..f3979628943e 100644
--- a/init/main.c
+++ b/init/main.c
@@ -889,7 +889,11 @@ asmlinkage __visible void __init __no_sanitize_address __noreturn start_kernel(v
 
 	cgroup_init_early();
 
-	local_irq_disable();
+	if (!raw_irqs_disabled()) {
+		raw_local_irq_disable();
+		if (IS_ENABLED(CONFIG_DEBUG_IRQFLAGS))
+			WARN_ONCE(1, "arch should call start_kernel with arch_irqs_disabled\n");
+	}
 	early_boot_irqs_disabled = true;
 
 	/*
-- 
2.40.1