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Date:   Tue, 7 Nov 2017 11:13:22 +0100
From:   Stanislaw Gruszka <sgruszka@redhat.com>
To:     Richard Genoud <richard.genoud@gmail.com>
Cc:     Helmut Schaa <helmut.schaa@googlemail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-wireless@vger.kernel.org
Subject: Re: Soft lockup in rt2x00usb_work_rxdone()
Message-ID: <20171107101320.GA12140@redhat.com>
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On Tue, Nov 07, 2017 at 11:06:39AM +0100, Richard Genoud wrote:
> > 3 short articles how to configure and use ftrace are here:
> > https://lwn.net/Articles/365835/
> > https://lwn.net/Articles/366796/
> > https://lwn.net/Articles/370423/
> >
> I tried with ftrace, but I don't think there's a way to dump the trace
> when there's a soft lock-up
> (I can't do anything after the unbind, even the heartbeat led stopped blinking).
> I saw the /proc/sys/kernel/ftrace_dump_on_oops file, but there's no
> /proc/sys/kernel/ftrace_dump_on_soft_lock-up file :)

You should configure function trace with rt2x* functions. After that
start tracing, unbind the device, then stop tracing and provide trace
output.

Thanks
Stanislaw

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