From: Keith Owens <kaos@ocs.com.au>
To: linux-kernel@vger.kernel.org
Cc: "Ingo Molnar" <mingo@elte.hu>, "Thomas Gleixner" <tglx@linutronix.de>
Subject: 2.6.18-rc4 i386 CONFIG_4KSTACKS does not use the hardirq stack
Date: Fri, 25 Aug 2006 13:16:37 +1000 [thread overview]
Message-ID: <7109.1156475797@kao2.melbourne.sgi.com> (raw)
2.6.18-rc4 arch/i386/kernel/irq.c::do_IRQ has this code:
if (!irq_desc[irq].handle_irq) {
__do_IRQ(irq, regs);
goto out_exit;
}
#ifdef CONFIG_4KSTACKS
curctx = (union irq_ctx *) current_thread_info();
irqctx = hardirq_ctx[smp_processor_id()];
...
All registered irqs on my system have a NULL handle_irq so do_IRQ
always calls __do_IRQ on the current stack, it never switches to the
hardirq_ctx stack. Removing the test is trivial and it boots and runs
without the test for !irq_desc[irq].handle_irq, but why was the test
put there in the first place?
Note: with that test removed, do_IRQ runs on the hardirq stack, but
struct thread_info is not updated accordingly so backtrace is wrong. I
can fix that as well, but I need to understand the test for handle_irq
first.
reply other threads:[~2006-08-25 3:17 UTC|newest]
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