From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [RFC PATCH] i2c: acpi: put device when verifying client fails Date: Thu, 12 Mar 2020 17:14:50 +0200 Message-ID: <20200312151450.GZ1922688@smile.fi.intel.com> References: <20200312133244.9564-1-wsa@the-dreams.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20200312133244.9564-1-wsa@the-dreams.de> Sender: linux-acpi-owner@vger.kernel.org To: Wolfram Sang Cc: linux-i2c@vger.kernel.org, linux-acpi@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Mika Westerberg , Jarkko Nikula , Wolfram Sang , Geert Uytterhoeven List-Id: linux-i2c@vger.kernel.org On Thu, Mar 12, 2020 at 02:32:44PM +0100, Wolfram Sang wrote: > From: Wolfram Sang > > i2c_verify_client() can fail, so we need to put the device when that > happens. I hope it's not a CoVID-19 makes me mistakenly commented in the first place. :-) So, theoretically below is possible, but practically it's doubtful. The I2CSerialBusV2() ACPI resource can be present solely in I²C slave device nodes according to the specification. However, we might have two possible cases a) screwed up ACPI table; b) I²C master which in turn is I²C slave. While a) has been so far unseen, b) case sounds like plasible for I²C muxes IIUC. So, I agree with the patch, and sorry for the first reaction. Reviewed-by: Andy Shevchenko > Fixes: 525e6fabeae2 ("i2c / ACPI: add support for ACPI reconfigure notifications") > Reported-by: Geert Uytterhoeven > Signed-off-by: Wolfram Sang > --- > > RFC because I don't know if it can be that the returned dev is not an > i2c_client. Yet, since it can happen theoretically, I think we should > have the checks. > > drivers/i2c/i2c-core-acpi.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c > index 8f3dbc97a057..8b0ff780919b 100644 > --- a/drivers/i2c/i2c-core-acpi.c > +++ b/drivers/i2c/i2c-core-acpi.c > @@ -394,9 +394,17 @@ EXPORT_SYMBOL_GPL(i2c_acpi_find_adapter_by_handle); > static struct i2c_client *i2c_acpi_find_client_by_adev(struct acpi_device *adev) > { > struct device *dev; > + struct i2c_client *client; > > dev = bus_find_device_by_acpi_dev(&i2c_bus_type, adev); > - return dev ? i2c_verify_client(dev) : NULL; > + if (!dev) > + return NULL; > + > + client = i2c_verify_client(dev); > + if (!client) > + put_device(dev); > + > + return client; > } > > static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value, > -- > 2.20.1 > -- With Best Regards, Andy Shevchenko