From: Peter Zijlstra <peterz@infradead.org>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Adrian Bunk <bunk@kernel.org>,
ananth@in.ibm.com, anil.s.keshavamurthy@intel.com,
davem@davemloft.net, bugme-daemon@bugzilla.kernel.org,
jean-marc LACROIX <jeanmarc.lacroix@free.Fr>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [Bug 10489] Kprobe smoke test lockdep warning
Date: Tue, 22 Apr 2008 18:05:58 +0200 [thread overview]
Message-ID: <1208880358.7115.285.camel@twins> (raw)
In-Reply-To: <480E034F.5@redhat.com>
On Tue, 2008-04-22 at 11:25 -0400, Masami Hiramatsu wrote:
> Peter Zijlstra wrote:
> > On Tue, 2008-04-22 at 15:09 +0200, Peter Zijlstra wrote:
> >> On Mon, 2008-04-21 at 18:54 -0400, Masami Hiramatsu wrote:
> >>> Thank you for reporting.
> >>>
> >>> Actually, kprobes tries to fixup thread's flags in post_kprobe_handler
> >>> (which is called from kprobe_exceptions_notify) by
> >>> trace_hardirqs_fixup_flags(pt_regs->flags). However, even the irq flag
> >>> is set in pt_regs->flags, true hardirq is still off until returning
> >>> from do_debug. Thus, lockdep assumes that hardirq is off without annotation.
> >
> > Ah, can you clarrify? pt_regs->flags will only be set when returning to
> > the original trap site? in that case we should not need a lockdep
> > annotation I guess, unless its allowed and exptected for the int3 site
> > to change IRQ state.
>
> As far as I took a look at the lockdep, your suggestion is correct.
> post_kprobe_handler should not set a lockdep annotation, because
> processor's IF is not changed yet in that time.
That much was clear; but when _will_ it be changed?
next prev parent reply other threads:[~2008-04-22 16:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-21 15:06 [Bug 10489] Kprobe smoke test lockdep warning Adrian Bunk
2008-04-21 15:13 ` Vegard Nossum
2008-04-21 22:54 ` Masami Hiramatsu
2008-04-22 13:09 ` Peter Zijlstra
2008-04-22 13:26 ` Peter Zijlstra
2008-04-22 15:25 ` Masami Hiramatsu
2008-04-22 16:05 ` Peter Zijlstra [this message]
2008-04-22 16:23 ` Masami Hiramatsu
2008-04-22 19:51 ` Masami Hiramatsu
2008-04-22 16:18 ` Masami Hiramatsu
2008-07-15 9:19 ` Ingo Molnar
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