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From: Andy Lutomirski <luto@amacapital.net>
Date: Mon, 7 Mar 2016 10:04:21 -0800
Message-ID: <CALCETrU-VctJ2q3ymQQ=n5uhA3x1Rxz99629zy=-acaofyDwOg@mail.gmail.com>
Subject: Re: [PATCH] usbhid: Fix lockdep unannotated irqs-off warning
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Jiri Kosina <jikos@kernel.org>, Sedat Dilek <sedat.dilek@gmail.com>,
        Alan Stern <stern@rowland.harvard.edu>, Tejun Heo <tj@kernel.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Andy Lutomirski <luto@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        USB list <linux-usb@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
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On Mon, Mar 7, 2016 at 9:30 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Mon, 7 Mar 2016 18:24:12 +0100 (CET)
> Jiri Kosina <jikos@kernel.org> wrote:
>
>> > So, if Clang is producing wrong X86 code here, is it possible to turn
>> > interrupts on/off manually? But, hmm that affects other places as well
>> > in the Linux sources, so.
>>
>> This issue needs to be handled in the compiler.
>>
>
> Exactly. The compiler may get away with this in userspace (maybe), but
> for the kernel, it is definitely a show stopper. Especially if it knows
> that an asm() may be called.

It's broken for user code that fiddles with AC, too.

--Andy