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From:   "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" <valdis.kletnieks@vt.edu>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     Guenter Roeck <linux@roeck-us.net>,
        Mark Starovoytov <mstarovoitov@marvell.com>,
        Igor Russkikh <irusskikh@marvell.com>,
        "David S. Miller" <davem@davemloft.net>,
        Greg KH <gregkh@linuxfoundation.org>,
        "Ahmed S. Darwish" <a.darwish@linutronix.de>,
        linux-kernel@vger.kernel.org, mingo@redhat.com, paulmck@kernel.org,
        peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de,
        will@kernel.org
Subject: Re: [PATCH] Revert "seqlock: lockdep assert non-preemptibility on seqcount_t write"
In-Reply-To: <20200819070022.semyxepadnvtmtcr@linutronix.de>
References: <20200810085954.GA1591892@kroah.com> <20200810095428.2602276-1-a.darwish@linutronix.de> <20200810100502.GA2406768@kroah.com> <bcf94ea2-05e6-2212-f732-b9a79a142f7e@roeck-us.net> <169454.1597791078@turing-police> <fa442483-00b5-169e-dac2-71fbf8307117@roeck-us.net>
 <20200819070022.semyxepadnvtmtcr@linutronix.de>
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Date:   Wed, 19 Aug 2020 03:34:03 -0400
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On Wed, 19 Aug 2020 09:00:22 +0200, Sebastian Andrzej Siewior said:
> On 2020-08-18 17:56:49 [-0700], Guenter Roeck wrote:
> > Nice catch. FWIW, there is no obvious reason why this would need to be atomic.
> > The calling code does not set a lock, meaning there can be two (or more)
> > callers entering this code. Weird, especially since the code looks like it
> > would actually need a mutex to work correctly. It might be interesting to
> > see what happens if there are, say, half a dozen scripts/processes trying
> > to read the hwmon attribute introduced by this patch at the same time.
>
> => https://lkml.kernel.org/r/20200818161439.3dkf6jzp3vuwmvvh@linutronix.de

Looks reasonable to me, though I've not verified that it's preemptible at that
point...

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