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From:   "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" <valdis.kletnieks@vt.edu>
To:     Guenter Roeck <linux@roeck-us.net>,
        Mark Starovoytov <mstarovoitov@marvell.com>,
        Igor Russkikh <irusskikh@marvell.com>,
        "David S. Miller" <davem@davemloft.net>
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        bigeasy@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"
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Date:   Tue, 18 Aug 2020 18:51:18 -0400
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On Mon, 10 Aug 2020 07:10:32 -0700, Guenter Roeck said:
> > 	ERROR: modpost: "__bad_udelay" [drivers/net/ethernet/aquantia/atlanti=
c/atlantic.ko] undefined!
> > =

>
> I don't think that is new. If anything, it is surprising that builds don=
't fail more
> widely because of it. AFAICS it was introduced back in 2018 (a hot 50-ms=
 delay loop
> really isn't such a good idea).

Well...it wasn't broken in next-20200720.  A bit of poking with nm,
and building hw_atl/hw_atl_b0.s, it looks like the culprit is this commit:

commit 8dcf2ad39fdb2d183b7bd4307c837713e3150b9a
Author: Mark Starovoytov <mstarovoitov@marvell.com>
Date:   Mon Jul 20 21:32:44 2020 +0300

    net: atlantic: add hwmon getter for MAC temperature

specifically this chunk around line 1634 of hw_atl/hw_atl_b0.c:


+       err =3D readx_poll_timeout_atomic(hw_atl_b0_ts_ready_and_latch_hig=
h_get,
+                                       self, val, val =3D=3D 1, 10000U, 5=
00000U);

And doing a 'git revert' makes the build work....