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Message-ID: <20231019114559.5a81741e@bootlin.com>
Date: Thu, 19 Oct 2023 11:45:59 +0200
From: Herve Codina <herve.codina@...tlin.com>
To: Peter Rosin <peda@...ntia.se>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>,
linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
Allan Nielsen <allan.nielsen@...rochip.com>,
Horatiu Vultur <horatiu.vultur@...rochip.com>,
Steen Hegelund <steen.hegelund@...rochip.com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 1/3] i2c: muxes: i2c-mux-pinctrl: Use
of_get_i2c_adapter_by_node()
Hi Peter,
On Thu, 19 Oct 2023 11:25:35 +0200
Peter Rosin <peda@...ntia.se> wrote:
> Hi!
>
> 2023-10-19 at 09:35, Herve Codina wrote:
> > i2c-mux-pinctrl uses the pair of_find_i2c_adapter_by_node() /
> > i2c_put_adapter(). These pair alone is not correct to properly lock the
> > I2C parent adapter.
> >
> > Indeed, i2c_put_adapter() decrements the module refcount while
> > of_find_i2c_adapter_by_node() does not increment it. This leads to an
> > overflow over zero of the parent adapter user counter.
>
> Perhaps "... underflow of the parent module refcount."?
Yes, will be changed in the next iteration.
>
> >
> > Use the dedicated function, of_get_i2c_adapter_by_node(), to handle
> > correctly the module refcount.
> >
> > Signed-off-by: Herve Codina <herve.codina@...tlin.com>
>
> Good find, and sorry about that!
>
> Fixes: c4aee3e1b0de ("i2c: mux: pinctrl: remove platform_data")
> Acked-by: Peter Rosin <peda@...ntia.se>
>
Will be added in the next iteration.
Thanks for the review,
Hervé
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