From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wolfram Sang <wsa@the-dreams.de>
Subject: Re: [RFCv3] i2c: hold the core_lock for the whole execution of
 i2c_register_adapter()
Date: Sat, 21 Mar 2020 20:15:32 +0100
Message-ID: <20200321191532.GF5632@ninjato>
References: <20191008163956.GB566933@t480s.localdomain>
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To: Slawomir Stepien <sst@poczta.fm>
Cc: linux-i2c@vger.kernel.org, krzysztof.adamski@nokia.com, jakub.lewalski@nokia.com, slawomir.stepien@nokia.com, alexander.sverdlin@nokia.com


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Hi Slawomir,

On Tue, Oct 08, 2019 at 06:39:56PM +0200, Slawomir Stepien wrote:
> From: S=C5=82awomir St=C4=99pie=C5=84 <slawomir.stepien@nokia.com>
>=20
> There is a race condition between the i2c_get_adapter() and the
> i2c_add_adapter() if this mutex isn't hold for the whole execution of
> i2c_register_adapter().
>=20
> If the mutex isn't locked, it is possible to find idr that points to
> adapter that hasn't been registered yet (i.e. it's
> kobj.state_initialized is still false), which will end up with warning
> message:
>=20
> "... is not initialized, yet kobject_get() is being called."
>=20
> This patch will change how the locking is arranged around
> i2c_register_adapter() call and will prevent such situations. The part
> of the i2c_register_adapter() that do not need to be under the lock has
> been moved to a new function i2c_process_adapter.
>=20
> Signed-off-by: S=C5=82awomir St=C4=99pie=C5=84 <slawomir.stepien@nokia.co=
m>

Thank you for tackling this one and sorry for the late reply.

Do you have a test case for me so I could reproduce the bad case here?

Kind regards,

   Wolfram


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