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    SubjectRe: [PATCH] staging:iio:tsl2563 rewrite probe error handling
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    On Mon, Mar 5, 2012 at 1:27 PM, Benson Leung <bleung@chromium.org> wrote:
    > Looks good to me.

    Thanks Benson!

    cheers,
    grant

    >
    > Reviewed-by: Benson Leung <bleung@chromium.org>
    >
    > On Mon, Mar 5, 2012 at 9:15 AM, Grant Grundler <grundler@chromium.org>
    > wrote:
    >>
    >> tsl2563 probe function has two minor issues with it's error handling
    >> paths:
    >> 1) it is silent (did not report errors to dmesg)
    >> 2) did not return failure code (mixed up use of ret and err)
    >>
    >> and two major issues:
    >> 3) goto fail2 would corrupt a free memory pool ("double free")
    >> 4) device registration failure did NOT cancel/flush delayed work.
    >>   (and thus dereference a freed data structure later)
    >>
    >> The "double free" is subtle and was introduced with this change:
    >>    Author: Jonathan Cameron <jic23@cam.ac.uk>
    >>    Date:   Mon Apr 18 12:58:55 2011 +0100
    >>    staging:iio:tsl2563 take advantage of new iio_device_allocate private
    >> data.
    >>
    >> Originally, chip was allocated seperately. Now it's appended to the
    >> indio_dev by iio_allocate_device(sizeof(*chip)). So we only need one
    >> kfree call as well (in iio_free_device()).
    >>
    >> Signed-off-by: Grant Grundler <grundler@chromium.org>
    >> ---
    >>  Gory details of tracking this down are here:
    >>    http://crosbug.com/26819
    >>
    >>  Despite iio_device_registration failing, system can at least now boot.
    >>  Will follow up with a fix to "double register : in_intensity_both_raw"
    >>  error that is included in the bug report.
    >>
    >>  drivers/staging/iio/light/tsl2563.c |   39
    >> +++++++++++++++++++++++-----------
    >>  1 files changed, 26 insertions(+), 13 deletions(-)
    >>
    >> diff --git a/drivers/staging/iio/light/tsl2563.c
    >> b/drivers/staging/iio/light/tsl2563.c
    >> index 7e984bc..bf6498b 100644
    >> --- a/drivers/staging/iio/light/tsl2563.c
    >> +++ b/drivers/staging/iio/light/tsl2563.c
    >> @@ -705,7 +705,6 @@ static int __devinit tsl2563_probe(struct i2c_client
    >> *client,
    >>        struct tsl2563_chip *chip;
    >>        struct tsl2563_platform_data *pdata = client->dev.platform_data;
    >>        int err = 0;
    >> -       int ret;
    >>        u8 id = 0;
    >>
    >>        indio_dev = iio_allocate_device(sizeof(*chip));
    >> @@ -719,13 +718,15 @@ static int __devinit tsl2563_probe(struct i2c_client
    >> *client,
    >>
    >>        err = tsl2563_detect(chip);
    >>        if (err) {
    >> -               dev_err(&client->dev, "device not found, error %d\n",
    >> -err);
    >> +               dev_err(&client->dev, "detect error %d\n", -err);
    >>                goto fail1;
    >>        }
    >>
    >>        err = tsl2563_read_id(chip, &id);
    >> -       if (err)
    >> +       if (err) {
    >> +               dev_err(&client->dev, "read id error %d\n", -err);
    >>                goto fail1;
    >> +       }
    >>
    >>        mutex_init(&chip->lock);
    >>
    >> @@ -748,40 +749,52 @@ static int __devinit tsl2563_probe(struct i2c_client
    >> *client,
    >>        indio_dev->num_channels = ARRAY_SIZE(tsl2563_channels);
    >>        indio_dev->dev.parent = &client->dev;
    >>        indio_dev->modes = INDIO_DIRECT_MODE;
    >> +
    >>        if (client->irq)
    >>                indio_dev->info = &tsl2563_info;
    >>        else
    >>                indio_dev->info = &tsl2563_info_no_irq;
    >> +
    >>        if (client->irq) {
    >> -               ret = request_threaded_irq(client->irq,
    >> +               err = request_threaded_irq(client->irq,
    >>                                           NULL,
    >>                                           &tsl2563_event_handler,
    >>                                           IRQF_TRIGGER_RISING |
    >> IRQF_ONESHOT,
    >>                                           "tsl2563_event",
    >>                                           indio_dev);
    >> -               if (ret)
    >> -                       goto fail2;
    >> +               if (err) {
    >> +                       dev_err(&client->dev, "irq request error %d\n",
    >> -err);
    >> +                       goto fail1;
    >> +               }
    >>        }
    >> +
    >>        err = tsl2563_configure(chip);
    >> -       if (err)
    >> -               goto fail3;
    >> +       if (err) {
    >> +               dev_err(&client->dev, "configure error %d\n", -err);
    >> +               goto fail2;
    >> +       }
    >>
    >>        INIT_DELAYED_WORK(&chip->poweroff_work, tsl2563_poweroff_work);
    >> +
    >>        /* The interrupt cannot yet be enabled so this is fine without lock
    >> */
    >>        schedule_delayed_work(&chip->poweroff_work, 5 * HZ);
    >>
    >> -       ret = iio_device_register(indio_dev);
    >> -       if (ret)
    >> +       err = iio_device_register(indio_dev);
    >> +       if (err) {
    >> +               dev_err(&client->dev, "iio registration error %d\n",
    >> -err);
    >>                goto fail3;
    >> +       }
    >>
    >>        return 0;
    >> +
    >>  fail3:
    >> +       cancel_delayed_work(&chip->poweroff_work);
    >> +       flush_scheduled_work();
    >> +fail2:
    >>        if (client->irq)
    >>                free_irq(client->irq, indio_dev);
    >> -fail2:
    >> -       iio_free_device(indio_dev);
    >>  fail1:
    >> -       kfree(chip);
    >> +       iio_free_device(indio_dev);
    >>        return err;
    >>  }
    >>
    >> --
    >> 1.7.3.4
    >>
    >
    >
    >
    > --
    > Benson Leung
    > Software Engineer, Chrom* OS
    > bleung@chromium.org
    >
    --
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