On 20.11.20 12:59, Peter Zijlstra wrote:

On Fri, Nov 20, 2020 at 12:46:23PM +0100, Juergen Gross wrote:

quoted

+static __always_inline void arch_local_irq_restore(unsigned long flags)
+{
+	if (!arch_irqs_disabled_flags(flags))
+		arch_local_irq_enable();
+}

If someone were to write horrible code like:

	local_irq_disable();
	local_irq_save(flags);
	local_irq_enable();
	local_irq_restore(flags);

we'd be up some creek without a paddle... now I don't _think_ we have
genius code like that, but I'd feel saver if we can haz an assertion in
there somewhere...

Maybe something like:

#ifdef CONFIG_DEBUG_ENTRY // for lack of something saner
	WARN_ON_ONCE((arch_local_save_flags() ^ flags) & X86_EFLAGS_IF);
#endif

At the end?

I'd like to, but using WARN_ON_ONCE() in include/asm/irqflags.h sounds
like a perfect receipt for include dependency hell.

We could use a plain asm("ud2") instead.


Juergen